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Sample records for exhuast plumes gasrad

  1. ASSESSMENT OF PLUME DIVING

    Science.gov (United States)

    This presentation presents an assessment of plume diving. Observations included: vertical plume delineation at East Patchogue, NY showed BTEX and MTBE plumes sinking on either side of a gravel pit; Lake Druid TCE plume sank beneath unlined drainage ditch; and aquifer recharge/dis...

  2. Solar Coronal Plumes

    Directory of Open Access Journals (Sweden)

    Giannina Poletto

    2015-12-01

    Full Text Available Polar plumes are thin long ray-like structures that project beyond the limb of the Sun polar regions, maintaining their identity over distances of several solar radii. Plumes have been first observed in white-light (WL images of the Sun, but, with the advent of the space era, they have been identified also in X-ray and UV wavelengths (XUV and, possibly, even in in situ data. This review traces the history of plumes, from the time they have been first imaged, to the complex means by which nowadays we attempt to reconstruct their 3-D structure. Spectroscopic techniques allowed us also to infer the physical parameters of plumes and estimate their electron and kinetic temperatures and their densities. However, perhaps the most interesting problem we need to solve is the role they cover in the solar wind origin and acceleration: Does the solar wind emanate from plumes or from the ambient coronal hole wherein they are embedded? Do plumes have a role in solar wind acceleration and mass loading? Answers to these questions are still somewhat ambiguous and theoretical modeling does not provide definite answers either. Recent data, with an unprecedented high spatial and temporal resolution, provide new information on the fine structure of plumes, their temporal evolution and relationship with other transient phenomena that may shed further light on these elusive features.

  3. Chemistry in aircraft plumes

    Energy Technology Data Exchange (ETDEWEB)

    Kraabol, A.G.; Stordal, F.; Knudsen, S. [Norwegian Inst. for Air Research, Kjeller (Norway); Konopka, P. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere

    1997-12-31

    An expanding plume model with chemistry has been used to study the chemical conversion of NO{sub x} to reservoir species in aircraft plumes. The heterogeneous conversion of N{sub 2}O{sub 5} to HNO{sub 3}(s) has been investigated when the emissions take place during night-time. The plume from an B747 has been simulated. During a ten-hour calculation the most important reservoir species was HNO{sub 3} for emissions at noon. The heterogeneous reactions had little impact on the chemical loss of NO{sub x} to reservoir species for emissions at night. (author) 4 refs.

  4. Do Plumes Suck?

    Science.gov (United States)

    Braun, M. G.; Sohn, R. A.; Ribe, N. M.

    2001-12-01

    Geophysical observations at plumes, ridges, and arcs indicate that the the volcanic accretionary zone is much narrower than the inferred melt production region in the upwelling mantle. For ridges and arcs, lateral pressure gradients induced by advection of viscous asthenospheric mantle have been proposed as a potential mechanism for focusing melts to the accretionary center [Phipps Morgan, 1987; Spiegelman and McKenzie, 1987]. For ridges and arcs with asthenospheric viscosities >=1021 Paṡs, the magnitude of the lateral pressure gradients associated with viscous corner flow are comparable to vertical melt buoyancy (Δ ρ g). Plumes, however, differ from ridges and arcs in that mantle flow is driven primarily by buoyancy of the upwelling solid as opposed to viscous drag induced by surface plate motions. This difference in driving forces changes the relationship between the solid flow field and the resulting pressure gradients. We use numerical models to examine the influence of lateral pressure gradients from solid advection in plumes. We calculate the stream function and pressure field in the solid induced by a buoyant cylinder beneath a stationary lithosphere using the method of Ribe and Christensen [1999] after Pozrikidis [1997]. Initial results suggest that lateral pressure gradients may draw melt into the top of the plume towards the flow stagnation point. However, the largest flow-induced pressure gradients are oriented vertically within the buoyant plume. Compression where the plume impinges on the lithospheric lid has the potential to impede the vertical migration of melt within the plume. The magnitude of the flow-induced pressure gradients scales with the strength of the buoyant upwelling. However, unlike ridges and arcs, asthenospheric viscosity has little effect on the pressure gradients, because velocity and viscosity of plume material are interdependent. We explore the possible role of these pressure gradients in melt migration at plume and ridge-plume

  5. Plume-induced subduction

    Science.gov (United States)

    Gerya, T.; Stern, R. J.; Baes, M.; Sobolev, S. V.; Whattam, S. A.

    2016-12-01

    Dominant present-day subduction initiation mechanisms require acting plate forces and/or pre-existing zones of lithospheric weakness, which are themselves consequences of plate tectonics. In contrast, recently discovered plume-induced subduction initiation could have started the first subduction zone without pre-existing plate tectonics. Here, we investigate this new mechanism with high-resolution 3D numerical thermomechanical modeling experiments. We show that typical plume-induced subduction dynamics is subdivided into five different stages: (1) oceanic plateau formation by arrival of a mantle plume head; (2) formation of an incipient trench and a descending nearly-circular slab at the plateau margins; (3) tearing of the circular slab; (4) formation of several self-sustained retreating subduction zones and (5) cooling and spreading of the new lithosphere formed between the retreating subduction zones. At the final stage of plume-induced subduction initiation, a mosaic of independently moving, growing and cooling small oceanic plates heading toward individual retreating subduction zones forms. The plates are separated by spreading centers, triple junctions and transform faults and thus the newly formed multi-slab subduction system operates as an embryonic plate tectonic cell. We demonstrate that three key physical factors combine to trigger self-sustained plume-induced subduction: (1) old negatively buoyant oceanic lithosphere; (2) intense weakening of the lithosphere by plume-derived magmas; and (3) lubrication of the forming subduction interface by hydrated oceanic crust. We furthermore discuss that plume-induced subduction, which is rare at present day conditions, may have been common in the Precambrian time and likely started global plate tectonics on Earth.

  6. Dilution in Transition Zone between Rising Plumes and Surface Plumes

    DEFF Research Database (Denmark)

    Larsen, Torben

    2004-01-01

    The papers presents some physical experiments with the dilution of sea outfall plumes with emphasize on the transition zone where the relative fast flowing vertical plume turns to a horizontal surface plume following the slow sea surface currents. The experiments show that a considerable dilution...

  7. Turbulent buoyant jets and plumes

    CERN Document Server

    Rodi, Wolfgang

    The Science & Applications of Heat and Mass Transfer: Reports, Reviews, & Computer Programs, Volume 6: Turbulent Buoyant Jets and Plumes focuses on the formation, properties, characteristics, and reactions of turbulent jets and plumes. The selection first offers information on the mechanics of turbulent buoyant jets and plumes and turbulent buoyant jets in shallow fluid layers. Discussions focus on submerged buoyant jets into shallow fluid, horizontal surface or interface jets into shallow layers, fundamental considerations, and turbulent buoyant jets (forced plumes). The manuscript then exami

  8. On predicting mantle mushroom plumes

    Directory of Open Access Journals (Sweden)

    Ka-Kheng Tan

    2011-04-01

    Top cooling may produce plunging plumes of diameter of 585 km and at least 195 Myr old. The number of cold plumes is estimated to be 569, which has not been observed by seismic tomography or as cold spots. The cold plunging plumes may overwhelm and entrap some of the hot rising plumes from CMB, so that together they may settle in the transition zone.

  9. Evaluation of Visible Plumes.

    Science.gov (United States)

    Brennan, Thomas

    Developed for presentation at the 12th Conference on Methods in Air Pollution and Industrial Hygiene Studies, University of Southern California, April, 1971, this outline discusses plumes with contaminants that are visible to the naked eye. Information covers: (1) history of air pollution control regulations, (2) need for methods of evaluating…

  10. Thermal plumes in ventilated rooms

    DEFF Research Database (Denmark)

    Kofoed, Peter; Nielsen, Peter V.

    1990-01-01

    The design of a displacement ventilation system involves determination of the flow rate in the thermal plumes. The flow rate in the plumes and the vertical temperature gradient influence each other, and they are influenced by many factors. This paper shows some descriptions of these effects. Free...... to be the only possible approach to obtain the volume flow in: thermal plumes in ventilated rooms....

  11. Investigation on balcony plume entrainment

    Institute of Scientific and Technical Information of China (English)

    刘方; NIELSEN; P; V; HEILSELBERG; P; BROHUS; H

    2009-01-01

    An investigation on the scenarios of the spill plume and its equation was presented,including two aspects,i.e.,the small-scale experiment and the numerical simulation. Two balcony spill plume models are assessed by comparing with the fire dynamic simulation (FDS) and small scale model experiment results. Besides validating the spill model by experiments,the effect of different fire locations on balcony plume is also discussed. The results show that the balcony equation in NFPA gives good predictions on the mass flow rate. And the balcony plume entrainment coefficient is independent of the fire location. This investigation is useful for the fire engineers in designing smoke control systems.

  12. Terrestrial Plume Impingement Testbed Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Masten Space Systems proposes to create a terrestrial plume impingement testbed for generating novel datasets for extraterrestrial robotic missions. This testbed...

  13. Thermal Plumes in Ventilated Rooms

    DEFF Research Database (Denmark)

    Kofoed, Peter; Nielsen, Peter V.

    The design of a displacement ventilation system involves determination of the flow rate in the thermal plumes. The flow rate in the plumes and the vertical temperature gradient influence each other, and they are influenced by many factors. This paper shows some descriptions of these effects....

  14. Dilution of Buoyant Surface Plumes

    DEFF Research Database (Denmark)

    Larsen, Torben; Petersen, Ole

    The purpose of present work is to establish a quantitative description of a surface plume which is valid for the range of density differences occurring in relation to sewage outfalls.......The purpose of present work is to establish a quantitative description of a surface plume which is valid for the range of density differences occurring in relation to sewage outfalls....

  15. Smoke plumes: Emissions and effects

    Science.gov (United States)

    Susan O' Neill; Shawn Urbanski; Scott Goodrick; Sim Larkin

    2017-01-01

    Smoke can manifest itself as a towering plume rising against the clear blue sky-or as a vast swath of thick haze, with fingers that settle into valleys overnight. It comes in many forms and colors, from fluffy and white to thick and black. Smoke plumes can rise high into the atmosphere and travel great distances across oceans and continents. Or smoke can remain close...

  16. Investigation of Balcony Plume Entrainment

    DEFF Research Database (Denmark)

    Liu, F.; Nielsen, Peter V.; Heiselberg, Per

    2009-01-01

    An investigation on the scenarios of the spill plume and its equation was presented in this paper. The study includes two aspects, i.e., the small-scale experiment and the numerical simulation. Two balcony spill plume models are assessed by comparing with the FDS (Fire Dynamic Simulation) and sma...... is independent of the fire location. The Investigations in this paper are useful for the fire engineers in designing smoke control systems.......An investigation on the scenarios of the spill plume and its equation was presented in this paper. The study includes two aspects, i.e., the small-scale experiment and the numerical simulation. Two balcony spill plume models are assessed by comparing with the FDS (Fire Dynamic Simulation) and small...... scale model experiment results. Besides validating the spill model by experiments, the effect of different fire location on balcony plume is also discussed. The results show that the balcony equation in NFPA would give good predictions on the mass flow rate. And the balcony plume entrainment coefficient...

  17. Active Volcanic Plumes on Io

    Science.gov (United States)

    1997-01-01

    This color image, acquired during Galileo's ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon (see inset at upper right), erupting over a caldera (volcanic depression) named Pillan Patera after a South American god of thunder, fire and volcanoes. The plume seen by Galileo is 140 kilometers (86 miles) high and was also detected by the Hubble Space Telescope. The Galileo spacecraft will pass almost directly over Pillan Patera in 1999 at a range of only 600 kilometers (373 miles).The second plume, seen near the terminator (boundary between day and night), is called Prometheus after the Greek fire god (see inset at lower right). The shadow of the 75-kilometer (45- mile) high airborne plume can be seen extending to the right of the eruption vent. The vent is near the center of the bright and dark rings. Plumes on Io have a blue color, so the plume shadow is reddish. The Prometheus plume can be seen in every Galileo image with the appropriate geometry, as well as every such Voyager image acquired in 1979. It is possible that this plume has been continuously active for more than 18 years. In contrast, a plume has never been seen at Pillan Patera prior to the recent Galileo and Hubble Space Telescope images.North is toward the top of the picture. The resolution is about 6 kilometers (3.7 miles) per picture element. This composite uses images taken with the green, violet and near infrared filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The images were obtained on June 28, 1997, at a range of more than 600,000 kilometers (372,000 miles).The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http

  18. Coastal river plumes: Collisions and coalescence

    Science.gov (United States)

    Warrick, Jonathan A.; Farnsworth, Katherine L.

    2017-02-01

    Plumes of buoyant river water spread in the ocean from river mouths, and these plumes influence water quality, sediment dispersal, primary productivity, and circulation along the world's coasts. Most investigations of river plumes have focused on large rivers in a coastal region, for which the physical spreading of the plume is assumed to be independent from the influence of other buoyant plumes. Here we provide new understanding of the spreading patterns of multiple plumes interacting along simplified coastal settings by investigating: (i) the relative likelihood of plume-to-plume interactions at different settings using geophysical scaling, (ii) the diversity of plume frontal collision types and the effects of these collisions on spreading patterns of plume waters using a two-dimensional hydrodynamic model, and (iii) the fundamental differences in plume spreading patterns between coasts with single and multiple rivers using a three-dimensional hydrodynamic model. Geophysical scaling suggests that coastal margins with numerous small rivers (watershed areas 100,000 km2). When two plume fronts meet, several types of collision attributes were found, including refection, subduction and occlusion. We found that the relative differences in pre-collision plume densities and thicknesses strongly influenced the resulting collision types. The three-dimensional spreading of buoyant plumes was found to be influenced by the presence of additional rivers for all modeled scenarios, including those with and without Coriolis and wind. Combined, these results suggest that plume-to-plume interactions are common phenomena for coastal regions offshore of the world's smaller rivers and for coastal settings with multiple river mouths in close proximity, and that the spreading and fate of river waters in these settings will be strongly influenced by these interactions. We conclude that new investigations are needed to characterize how plumes interact offshore of river mouths to better

  19. Exhaust Nozzle Plume and Shock Wave Interaction

    Science.gov (United States)

    Castner, Raymond S.; Elmiligui, Alaa; Cliff, Susan

    2013-01-01

    Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the exhaust plume. Both the nozzle exhaust plume shape and the tail shock shape may be affected by an interaction that may alter the vehicle sonic boom signature. The plume and shock interaction was studied using Computational Fluid Dynamics simulation on two types of convergent-divergent nozzles and a simple wedge shock generator. The nozzle plume effects on the lower wedge compression region are evaluated for two- and three-dimensional nozzle plumes. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the deflected lower plume boundary. The sonic boom pressure signature of the wedge is modified by the presence of the plume, and the computational predictions show significant (8 to 15 percent) changes in shock amplitude.

  20. Ship exhaust gas plume cooling

    NARCIS (Netherlands)

    Schleijpen, H.M.A.; Neele, P.P.

    2004-01-01

    The exhaust gas plume is an important and sometimes dominating contributor to the infrared signature of ships. Suppression of the infrared ship signatures has been studied by TNO for the Royal Netherlands Navy over considerable time. This study deals with the suppression effects, which can be

  1. Characterization of redox conditions in pollution plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Bjerg, Poul Løgstrup; Banwart, Steven A.

    2000-01-01

    Evalution of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few...

  2. Plasma plume MHD power generator and method

    Science.gov (United States)

    Hammer, J.H.

    1993-08-10

    A method is described of generating power at a situs exposed to the solar wind which comprises creating at separate sources at the situs discrete plasma plumes extending in opposed directions, providing electrical communication between the plumes at their source and interposing a desired electrical load in the said electrical communication between the plumes.

  3. Teaching the Mantle Plumes Debate

    Science.gov (United States)

    Foulger, G. R.

    2010-12-01

    There is an ongoing debate regarding whether or not mantle plumes exist. This debate has highlighted a number of issues regarding how Earth science is currently practised, and how this feeds into approaches toward teaching students. The plume model is an hypothesis, not a proven fact. And yet many researchers assume a priori that plumes exist. This assumption feeds into teaching. That the plume model is unproven, and that many practising researchers are skeptical, may be at best only mentioned in passing to students, with most teachers assuming that plumes are proven to exist. There is typically little emphasis, in particular in undergraduate teaching, that the origin of melting anomalies is currently uncertain and that scientists do not know all the answers. Little encouragement is given to students to become involved in the debate and to consider the pros and cons for themselves. Typically teachers take the approach that “an answer” (or even “the answer”) must be taught to students. Such a pedagogic approach misses an excellent opportunity to allow students to participate in an important ongoing debate in Earth sciences. It also misses the opportunity to illustrate to students several critical aspects regarding correct application of the scientific method. The scientific method involves attempting to disprove hypotheses, not to prove them. A priori assumptions should be kept uppermost in mind and reconsidered at all stages. Multiple working hypotheses should be entertained. The predictions of a hypothesis should be tested, and unpredicted observations taken as weakening the original hypothesis. Hypotheses should not be endlessly adapted to fit unexpected observations. The difficulty with pedagogic treatment of the mantle plumes debate highlights a general uncertainty about how to teach issues in Earth science that are not yet resolved with certainty. It also represents a missed opportunity to let students experience how scientific theories evolve, warts

  4. Compositional differentiation of Enceladus' plume

    Science.gov (United States)

    Khawaja, N.; Postberg, F.; Schmidt, J.

    2014-04-01

    The Cosmic Dust Analyser (CDA) on board the Cassini spacecraft sampled Enceladus' plume ice particles emanated directly from Enceladus' fractured south polar terrain (SPT), the so-called "Tiger Stripes", during two consecutive flybys (E17 and E18) in 2012. The spacecraft passed through the dense plume with a moderate velocity of ~7.5km/s, horizontally to the SPT with a closest approach (CA) at an altitude of ~75km almost directly over the south pole. In both flybys, spectra were recorded during a time interval of ~ ±3 minutes with respect to the closest approach achieving an average sampling rate of about 0.6 sec-1. We assume that the spacecraft passed through the plume during an interval of about ±60(sec) from the CA. Particles encountered before and after this period are predominately from the E-ring background in which Enceladus is embedded. Most CDA TOF-mass spectra are identified as one of three compositional types: (i) almost pure water (ii) organic rich and (iii) salt rich [2]. A Boxcar Analysis (BCA) is performed from a count database for compositional mapping of the plume along the space-craft trajectory. In BCA, counts of each spectrum type are integrated for a certain interval of time (box size). The integral of counts represents frequencies of compositional types in absolute abundances, which are converted later into proportions. This technique has been proven to be a suitable for inferring the compositional profiles from an earlier flyby (E5) [1]. The inferred compositional profiles show similar trends on E17 and E18. The abundances of different compositional types in the plume clearly differ from the Ering background and imply a compositional differentiation inside the plume. Following up the work of Schmidt et al, 2008 and Postberg et al, 2011 we can link different compositional types to different origins. The E17/E18 results are compared with the E5 flyby in 2008, which yielded the currently best compositional profile [2] but was executed at much

  5. Biogeochemistry of landfill leachate plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Kjeldsen, Peter; Bjerg, Poul Løgstrup

    2001-01-01

    the behavior of the contaminants in the plume as the leachate migrates away from the landfill. Diverse microbial communities have been identified in leachate plumes and are believed to be responsible for the redox processes. Dissolved organic C in the leachate, although it appears to be only slowly degradable...... when the volatile organic acids are gone, apparently acts as substrate for the microbial. redox processes. Several xenobiotic organic compounds have been found to be degradable in leachate contaminated groundwater, but degradation rates under anaerobic redox conditions have only been determined...... natural remediation, limiting the effects of the leachate on the groundwater to an area usually not exceeding 1000 m from the landfill. (C) 2001 Elsevier Science Ltd. All rights reserved....

  6. Magnetohydrodynamic waves in coronal polar plumes.

    Science.gov (United States)

    Nakariakov, Valery M

    2006-02-15

    Polar plumes are cool, dense, linear, magnetically open structures that arise from predominantly unipolar magnetic footpoints in the solar polar coronal holes. As the Alfvén speed is decreased in plumes in comparison with the surrounding medium, these structures are natural waveguides for fast and slow magnetoacoustic waves. The simplicity of the geometry of polar plumes makes them an ideal test ground for the study of magnetohydrodynamic (MHD) wave interaction with solar coronal structures. The review covers recent observational findings of compressible and incompressible waves in polar plumes with imaging and spectral instruments, and interpretation of the waves in terms of MHD theory.

  7. Propagation of light through ship exhaust plumes

    Science.gov (United States)

    van Iersel, M.; Mack, A.; van Eijk, A. M. J.; Schleijpen, H. M. A.

    2014-10-01

    Looking through the atmosphere, it is sometimes difficult to see the details of an object. Effects like scintillation and blur are the cause of these difficulties. Exhaust plumes of e.g. a ship can cause extreme scintillation and blur, making it even harder to see the details of what lies behind the plume. Exhaust plumes come in different shapes, sizes, and opaqueness and depending on atmospheric parameters like wind speed and direction, as well as engine settings (power, gas or diesel, etc.). A CFD model is used to determine the plume's flow field outside the stack on the basis of exhaust flow properties, the interaction with the superstructure of the ship, the meteorological conditions and the interaction of ship's motion and atmospheric wind fields. A modified version of the NIRATAM code performs the gas radiation calculations and provides the radiant intensity of the (hot) exhaust gases and the transmission of the atmosphere around the plume is modeled with MODTRAN. This allows assessing the irradiance of a sensor positioned at some distance from the ship and its plume, as function of the conditions that influence the spatial distribution and thermal properties of the plume. Furthermore, an assessment can be made of the probability of detecting objects behind the plume. This plume module will be incorporated in the TNO EOSTAR-model, which provides estimates of detection range and image quality of EO-sensors under varying meteorological conditions.

  8. Lidar measurements of plume statistics

    DEFF Research Database (Denmark)

    Ejsing Jørgensen, Hans; Mikkelsen, T.

    1993-01-01

    of measured crosswind concentration profiles, the following statistics were obtained: 1) Mean profile, 2) Root mean square profile, 3) Fluctuation intensities,and 4)Intermittency factors. Furthermore, some experimentally determined probability density functions (pdf's) of the fluctuations are presented. All...... the measured statistics are referred to a fixed and a 'moving' frame of reference, the latter being defined as a frame of reference from which the (low frequency) plume meander is removed. Finally, the measured statistics are compared with statistics on concentration fluctuations obtained with a simple puff...

  9. Plume spread and atmospheric stability

    Energy Technology Data Exchange (ETDEWEB)

    Weber, R.O. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The horizontal spread of a plume in atmospheric dispersion can be described by the standard deviation of horizontal direction. The widely used Pasquill-Gifford classes of atmospheric stability have assigned typical values of the standard deviation of horizontal wind direction and of the lapse rate. A measured lapse rate can thus be used to estimate the standard deviation of wind direction. It is examined by means of a large dataset of fast wind measurements how good these estimates are. (author) 1 fig., 2 refs.

  10. Characteristics of bubble plumes, bubble-plume bubbles and waves from wind-steepened wave breaking

    NARCIS (Netherlands)

    Leifer, I.; Caulliez, G.; Leeuw, G. de

    2007-01-01

    Observations of breaking waves, associated bubble plumes and bubble-plume size distributions were used to explore the coupled evolution of wave-breaking, wave properties and bubble-plume characteristics. Experiments were made in a large, freshwater, wind-wave channel with mechanical wind-steepened

  11. Simulation of plume rise: Study the effect of stably stratified turbulence layer on the rise of a buoyant plume from a continuous source by observing the plume centroid

    Science.gov (United States)

    Bhimireddy, Sudheer Reddy; Bhaganagar, Kiran

    2016-11-01

    Buoyant plumes are common in atmosphere when there exists a difference in temperature or density between the source and its ambience. In a stratified environment, plume rise happens until the buoyancy variation exists between the plume and ambience. In a calm no wind ambience, this plume rise is purely vertical and the entrainment happens because of the relative motion of the plume with ambience and also ambient turbulence. In this study, a plume centroid is defined as the plume mass center and is calculated from the kinematic equation which relates the rate of change of centroids position to the plume rise velocity. Parameters needed to describe the plume are considered as the plume radius, plumes vertical velocity and local buoyancy of the plume. The plume rise velocity is calculated by the mass, momentum and heat conservation equations in their differential form. Our study focuses on the entrainment velocity, as it depicts the extent of plume growth. This entrainment velocity is made up as sum of fractions of plume's relative velocity and ambient turbulence. From the results, we studied the effect of turbulence on the plume growth by observing the variation in the plume radius at different heights and the centroid height reached before loosing its buoyancy.

  12. Skylon Aerodynamics and SABRE Plumes

    Science.gov (United States)

    Mehta, Unmeel; Afosmis, Michael; Bowles, Jeffrey; Pandya, Shishir

    2015-01-01

    An independent partial assessment is provided of the technical viability of the Skylon aerospace plane concept, developed by Reaction Engines Limited (REL). The objectives are to verify REL's engineering estimates of airframe aerodynamics during powered flight and to assess the impact of Synergetic Air-Breathing Rocket Engine (SABRE) plumes on the aft fuselage. Pressure lift and drag coefficients derived from simulations conducted with Euler equations for unpowered flight compare very well with those REL computed with engineering methods. The REL coefficients for powered flight are increasingly less acceptable as the freestream Mach number is increased beyond 8.5, because the engineering estimates did not account for the increasing favorable (in terms of drag and lift coefficients) effect of underexpanded rocket engine plumes on the aft fuselage. At Mach numbers greater than 8.5, the thermal environment around the aft fuselage is a known unknown-a potential design and/or performance risk issue. The adverse effects of shock waves on the aft fuselage and plumeinduced flow separation are other potential risks. The development of an operational reusable launcher from the Skylon concept necessitates the judicious use of a combination of engineering methods, advanced methods based on required physics or analytical fidelity, test data, and independent assessments.

  13. Proceedings of plumes, plates and mineralisation symposium: an introduction

    CSIR Research Space (South Africa)

    Hatton, CJ

    1997-12-01

    Full Text Available of plume-theory. Mechanisms of magma formation are identified and plume positions and distances to their surface expression considered. Mantle plumes are considered as a heat and fluid source for the Witwatersrand gold deposits....

  14. The Alberta smoke plume observation study

    Directory of Open Access Journals (Sweden)

    K. Anderson

    2018-02-01

    Full Text Available A field project was conducted to observe and measure smoke plumes from wildland fires in Alberta. This study used handheld inclinometer measurements and photos taken at lookout towers in the province. Observations of 222 plumes were collected from 21 lookout towers over a 6-year period from 2010 to 2015. Observers reported the equilibrium and maximum plume heights based on the plumes' final levelling heights and the maximum lofting heights, respectively. Observations were tabulated at the end of each year and matched to reported fires. Fire sizes at assessment times and forest fuel types were reported by the province. Fire weather conditions were obtained from the Canadian Wildland Fire Information System (CWFIS. Assessed fire sizes were adjusted to the appropriate size at plume observation time using elliptical fire-growth projections. Though a logical method to collect plume observations in principle, many unanticipated issues were uncovered as the project developed. Instrument limitations and environmental conditions presented challenges to the investigators, whereas human error and the subjectivity of observations affected data quality. Despite these problems, the data set showed that responses to fire behaviour conditions were consistent with the physical processes leading to plume rise. The Alberta smoke plume observation study data can be found on the Canadian Wildland Fire Information System datamart (Natural Resources Canada, 2018 at http://cwfis.cfs.nrcan.gc.ca/datamart.

  15. Ablation plume dynamics in a background gas

    DEFF Research Database (Denmark)

    Amoruso, Salvatore; Schou, Jørgen; Lunney, James G.

    2010-01-01

    the expansion. The model also leads to an insightful treatment of the stopping behavior in dimensionless units for plumes and background gases of different atomic/molecular masses. The energetics of the plume dynamics can also be treated with this model. Experimental time-of-flight data of silver ions in a neon...

  16. Dynamics of fire plumes in verticle shear

    Science.gov (United States)

    Philip Cunningham; Scott L. Goodrick; Hussaini M. Yousuff; Rodman R. Linn; Chunmei Xia

    2003-01-01

    Plumes from wildfires and prescribed fires represent a critical aspect of smoke mangement and aire quality assessment, as as such it is important to understand the structure and dynamics of these plumes, both with respect to a basic understanding of the phenomena and with respect to an assessment of the validity of plumerise parameterizations over a wide variety of...

  17. Infrared Sensing of Buoyant Surface Plumes

    DEFF Research Database (Denmark)

    Petersen, Ole; Larsen, Torben

    1988-01-01

    This paper is concerned with laboratory experiments on buoyant surface plumes where heat is the source of buoyancy. Temperature distributions were measured at the water surface using infra-red sensing, and inside the waterbody a computer based measurement system was applied. The plume is described...

  18. Modelling oil plumes from subsurface spills.

    Science.gov (United States)

    Lardner, Robin; Zodiatis, George

    2017-11-15

    An oil plume model to simulate the behavior of oil from spills located at any given depth below the sea surface is presented, following major modifications to a plume model developed earlier by Malačič (2001) and drawing on ideas in a paper by Yapa and Zheng (1997). The paper presents improvements in those models and numerical testing of the various parameters in the plume model. The plume model described in this paper is one of the numerous modules of the well-established MEDSLIK oil spill model. The deep blowout scenario of the MEDEXPOL 2013 oil spill modelling exercise, organized by REMPEC, has been applied using the improved oil plume module of the MEDSLIK model and inter-comparison with results having the oil spill source at the sea surface are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Galileo observations of volcanic plumes on Io

    Science.gov (United States)

    Geissler, P.E.; McMillan, M.T.

    2008-01-01

    Io's volcanic plumes erupt in a dazzling variety of sizes, shapes, colors and opacities. In general, the plumes fall into two classes, representing distinct source gas temperatures. Most of the Galileo imaging observations were of the smaller, more numerous Prometheus-type plumes that are produced when hot flows of silicate lava impinge on volatile surface ices of SO2. Few detections were made of the giant, Pele-type plumes that vent high temperature, sulfur-rich gases from the interior of Io; this was partly because of the insensitivity of Galileo's camera to ultraviolet wavelengths. Both gas and dust spout from plumes of each class. Favorably located gas plumes were detected during eclipse, when Io was in Jupiter's shadow. Dense dust columns were imaged in daylight above several Prometheus-type eruptions, reaching heights typically less than 100 km. Comparisons between eclipse observations, sunlit images, and the record of surface changes show that these optically thick dust columns are much smaller in stature than the corresponding gas plumes but are adequate to produce the observed surface deposits. Mie scattering calculations suggest that these conspicuous dust plumes are made up of coarse grained “ash” particles with radii on the order of 100 nm, and total masses on the order of 106 kg per plume. Long exposure images of Thor in sunlight show a faint outer envelope apparently populated by particles small enough to be carried along with the gas flow, perhaps formed by condensation of sulfurous “snowflakes” as suggested by the plasma instrumentation aboard Galileo as it flew through Thor's plume [Frank, L.A., Paterson, W.R., 2002. J. Geophys. Res. (Space Phys.) 107, doi:10.1029/2002JA009240. 31-1]. If so, the total mass of these fine, nearly invisible particles may be comparable to the mass of the gas, and could account for much of Io's rapid resurfacing.

  20. Dynamics and Deposits of Coignimbrite Plumes

    Science.gov (United States)

    Engwell, Samantha; de'Michieli Vitturi, Mattia; Esposti Ongaro, Tomaso; Neri, Augusto

    2014-05-01

    Fine ash in the atmosphere poses a significant hazard, with potentially disastrous consequences for aviation and, on deposition, health and infrastructure. Fine-grained particles form a large proportion of ejecta in Plinian volcanic clouds. However, another common, but poorly studied phenomena exists whereby large amounts of fine ash are injected into the atmosphere. Coignimbrite plumes form as material is elutriated from the top of pyroclastic density currents. The ash in these plumes is considerably finer grained than that in Plinian plumes and can be distributed over thousands of kilometres in the atmosphere. Despite their significance, very little is known regarding coignimbrite plume formation and dispersion, predominantly due to the poor preservation of resultant deposits. As a result, consequences of coignimbrite plume formation are usually overlooked when conducting hazard and risk analysis. In this study, deposit characteristics and numerical models of plumes are combined to investigate the conditions required for coignimbrite plume formation. Coignimbrite deposits from the Campanian Ignimbrite eruption (Magnitude 7.7, 39 ka) are well sorted and very fine, with a mode of between 30 and 50 microns, and a significant component of respirable ash (less than 10 microns). Analogous distributions are found for coignimbrite deposits from Tungurahua 2006 and Volcan de Colima (2004-2006), amongst others, regardless of magnitude, type or chemistry of eruption. These results indicate that elutriation processes are the dominant control on coignimbrite grainsize distribution. To further investigate elutriation and coignimbrite plume dynamics, the numerical plume model of Bursik (2001) is applied. Model sensitivity analysis demonstrates that neutral buoyancy conditions (required for the formation of the plume) are controlled by a balance between temperature and gas mass flux in the upper most parts of the pyroclastic density current. In addition, results emphasize the

  1. Radiation from advanced solid rocket motor plumes

    Science.gov (United States)

    Farmer, Richard C.; Smith, Sheldon D.; Myruski, Brian L.

    1994-12-01

    The overall objective of this study was to develop an understanding of solid rocket motor (SRM) plumes in sufficient detail to accurately explain the majority of plume radiation test data. Improved flowfield and radiation analysis codes were developed to accurately and efficiently account for all the factors which effect radiation heating from rocket plumes. These codes were verified by comparing predicted plume behavior with measured NASA/MSFC ASRM test data. Upon conducting a thorough review of the current state-of-the-art of SRM plume flowfield and radiation prediction methodology and the pertinent data base, the following analyses were developed for future design use. The NOZZRAD code was developed for preliminary base heating design and Al2O3 particle optical property data evaluation using a generalized two-flux solution to the radiative transfer equation. The IDARAD code was developed for rapid evaluation of plume radiation effects using the spherical harmonics method of differential approximation to the radiative transfer equation. The FDNS CFD code with fully coupled Euler-Lagrange particle tracking was validated by comparison to predictions made with the industry standard RAMP code for SRM nozzle flowfield analysis. The FDNS code provides the ability to analyze not only rocket nozzle flow, but also axisymmetric and three-dimensional plume flowfields with state-of-the-art CFD methodology. Procedures for conducting meaningful thermo-vision camera studies were developed.

  2. A numerical study of the Magellan Plume

    Science.gov (United States)

    Palma, Elbio D.; Matano, Ricardo P.

    2012-05-01

    In this modeling study we investigate the dynamical mechanisms controlling the spreading of the Magellan Plume, which is a low-salinity tongue that extends along the Patagonian Shelf. Our results indicate that the overall characteristics of the plume (width, depth, spreading rate, etc.) are primarily influenced by tidal forcing, which manifests through tidal mixing and tidal residual currents. Tidal forcing produces a homogenization of the plume's waters and an offshore displacement of its salinity front. The interaction between tidal and wind-forcing reinforces the downstream and upstream buoyancy transports of the plume. The influence of the Malvinas Current on the Magellan Plume is more dominant north of 50°S, where it increases the along-shelf velocities and generates intrusions of saltier waters from the outer shelf, thus causing a reduction of the downstream buoyancy transport. Our experiments also indicate that the northern limit of the Magellan Plume is set by a high salinity discharge from the San Matias Gulf. Sensitivity experiments show that increments of the wind stress cause a decrease of the downstream buoyancy transport and an increase of the upstream buoyancy transport. Variations of the magnitude of the discharge produce substantial modifications in the downstream penetration of the plume and buoyancy transport. The Magellan discharge generates a northeastward current in the middle shelf, a recirculation gyre south of the inlet and a region of weak currents father north.

  3. Sensitivity of air quality simulation to smoke plume rise

    Science.gov (United States)

    Yongqiang Liu; Gary Achtemeier; Scott Goodrick

    2008-01-01

    Plume rise is the height smoke plumes can reach. This information is needed by air quality models such as the Community Multiscale Air Quality (CMAQ) model to simulate physical and chemical processes of point-source fire emissions. This study seeks to understand the importance of plume rise to CMAQ air quality simulation of prescribed burning to plume rise. CMAQ...

  4. Hydroxyl Tagging Velocimetry for Rocket Plumes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the need for non-intrusive sensors for rocket plume properties, we propose a laser-based velocity diagnostic that does not require seeding, works in high...

  5. Plume Diagnostics for Combustion Stability Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Sierra Engineering Inc. and Purdue University propose to develop a non-intrusive plume instrument capable of detecting and diagnosing combustion instability. This...

  6. Novel plume deflection concept testing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort will explore the feasibility and effectiveness of utilizing an electrically driven thermal shield for use as part of rocket plume deflectors. To...

  7. Near-glacier surveying of a subglacial discharge plume: Implications for plume parameterizations

    Science.gov (United States)

    Jackson, R. H.; Shroyer, E. L.; Nash, J. D.; Sutherland, D. A.; Carroll, D.; Fried, M. J.; Catania, G. A.; Bartholomaus, T. C.; Stearns, L. A.

    2017-07-01

    At tidewater glaciers, plume dynamics affect submarine melting, fjord circulation, and the mixing of meltwater. Models often rely on buoyant plume theory to parameterize plumes and submarine melting; however, these parameterizations are largely untested due to a dearth of near-glacier measurements. Here we present a high-resolution ocean survey by ship and remotely operated boat near the terminus of Kangerlussuup Sermia in west Greenland. These novel observations reveal the 3-D structure and transport of a near-surface plume, originating at a large undercut conduit in the glacier terminus, that is inconsistent with axisymmetric plume theory, the most common representation of plumes in ocean-glacier models. Instead, the observations suggest a wider upwelling plume—a "truncated" line plume of ˜200 m width—with higher entrainment and plume-driven melt compared to the typical axisymmetric representation. Our results highlight the importance of a subglacial outlet's geometry in controlling plume dynamics, with implications for parameterizing the exchange flow and submarine melt in glacial fjord models.

  8. Fire analog: a comparison between fire plumes and energy center cooling tower plumes

    Energy Technology Data Exchange (ETDEWEB)

    Orgill, M.M.

    1977-10-01

    Thermal plumes or convection columns associated with large fires are compared to thermal plumes from cooling towers and proposed energy centers to evaluate the fire analog concept. Energy release rates of mass fires are generally larger than for single or small groups of cooling towers but are comparable to proposed large energy centers. However, significant physical differences exist between cooling tower plumes and fire plumes. Cooling tower plumes are generally dominated by ambient wind, stability and turbulence conditions. Fire plumes, depending on burning rates and other factors, can transform into convective columns which may cause the fire behavior to become more violent. This transformation can cause strong inflow winds and updrafts, turbulence and concentrated vortices. Intense convective columns may interact with ambient winds to create significant downwind effects such as wakes and Karman vortex streets. These characteristics have not been observed with cooling tower plumes to date. The differences in physical characteristics between cooling tower and fire plumes makes the fire analog concept very questionable even though the approximate energy requirements appear to be satisfied in case of large energy centers. Additional research is suggested in studying the upper-level plume characteristics of small experimental fires so this information can be correlated with similar data from cooling towers. Numerical simulation of fires and proposed multiple cooling tower systems could also provide comparative data.

  9. Diagnostics of laser ablated plasma plumes

    DEFF Research Database (Denmark)

    Amoruso, S.; Toftmann, B.; Schou, Jørgen

    2004-01-01

    The effect of an ambient gas on the expansion dynamics of laser ablated plasmas has been studied for two systems by exploiting different diagnostic techniques. First, the dynamics of a MgB2 laser produced plasma plume in an Ar atmosphere has been investigated by space-and time-resolved optical...... of the laser ablated plasma plume propagation in a background gas. (C) 2003 Elsevier B.V All rights reserved....

  10. Density - Velocity Relationships in Explosive Volcanic Plumes

    Science.gov (United States)

    Fisher, M. A.; Kobs-Nawotniak, S. E.

    2015-12-01

    Positively buoyant volcanic plumes rise until the bulk density of the plume is equal to the density of the ambient atmosphere. As ambient air mixes with the plume, it lowers the plume bulk density; thus, the plume is diluted enough to reach neutral density in a naturally stratified atmospheric environment. We produced scaled plumes in analogue laboratory experiments by injecting a saline solution with a tracer dye into distilled water, using a high-pressure injection system. We recorded each eruption with a CASIO HD digital camera and used ImageJ's FeatureJ Edge toolbox to identify individual eddies. We used an optical flow software based off the ImageJ toolbox FlowJ to determine the velocities along the edge of each eddy. Eddy densities were calculated by mapping the dye concentration to the RGB digital color value. We overlaid the eddy velocities over the densities in order to track the behavioral relationship between the two variables with regard to plume motion. As an eddy's bulk density decreases, the vertical velocity decreases; this is a result of decreased mass, and therefore momentum, in the eddy. Furthermore as the density rate of change increases, the eddy deceleration increases. Eddies are most dense at their top and least dense at their bottom. The less dense sections of the eddies have lower vertical velocities than the sections of the eddies with the higher densities, relating to the expanding radial size of an eddy as it rises and the preferential ingestion of ambient air at the base of eddies. Thus the mixing rate in volcanic plumes fluctuates not only as a function of height as described by the classic 1D entrainment hypothesis, but also as a function of position in an eddy itself.

  11. OPAD data analysis. [Optical Plumes Anomaly Detection

    Science.gov (United States)

    Buntine, Wray L.; Kraft, Richard; Whitaker, Kevin; Cooper, Anita E.; Powers, W. T.; Wallace, Tim L.

    1993-01-01

    Data obtained in the framework of an Optical Plume Anomaly Detection (OPAD) program intended to create a rocket engine health monitor based on spectrometric detections of anomalous atomic and molecular species in the exhaust plume are analyzed. The major results include techniques for handling data noise, methods for registration of spectra to wavelength, and a simple automatic process for estimating the metallic component of a spectrum.

  12. A modeling of buoyant gas plume migration

    Energy Technology Data Exchange (ETDEWEB)

    Silin, D.; Patzek, T.; Benson, S.M.

    2008-12-01

    This work is motivated by the growing interest in injecting carbon dioxide into deep geological formations as a means of avoiding its atmospheric emissions and consequent global warming. Ideally, the injected greenhouse gas stays in the injection zone for a geologic time, eventually dissolves in the formation brine and remains trapped by mineralization. However, one of the potential problems associated with the geologic method of sequestration is that naturally present or inadvertently created conduits in the cap rock may result in a gas leakage from primary storage. Even in a supercritical state, the carbon dioxide viscosity and density are lower than those of the formation brine. Buoyancy tends to drive the leaked CO{sub 2} plume upward. Theoretical and experimental studies of buoyancy-driven supercritical CO{sub 2} flow, including estimation of time scales associated with plume evolution and migration, are critical for developing technology, monitoring policy, and regulations for safe carbon dioxide geologic sequestration. In this study, we obtain simple estimates of vertical plume propagation velocity taking into account the density and viscosity contrast between CO{sub 2} and brine. We describe buoyancy-driven countercurrent flow of two immiscible phases by a Buckley-Leverett type model. The model predicts that a plume of supercritical carbon dioxide in a homogeneous water-saturated porous medium does not migrate upward like a bubble in bulk water. Rather, it spreads upward until it reaches a seal or until it becomes immobile. A simple formula requiring no complex numerical calculations describes the velocity of plume propagation. This solution is a simplification of a more comprehensive theory of countercurrent plume migration (Silin et al., 2007). In a layered reservoir, the simplified solution predicts a slower plume front propagation relative to a homogeneous formation with the same harmonic mean permeability. In contrast, the model yields much higher

  13. Effects of plume afterburning on infrared spectroscopy

    Science.gov (United States)

    Zhu, Xijuan; Xu, Ying; Ma, Jing; Duan, Ran; Wu, Jie

    2017-10-01

    Contains H2, CO and unburned components of high-temperature plume of rocket engine, then injected into the atmosphere, continue to carry out the oxidation reaction in the plume near field region with the volume in the plume of oxygen in the air, two times burning. The afterburning is an important cause of infrared radiation intensification of propellant plume, which increases the temperature of the flame and changes the components of the gas, thus enhancing the infrared radiation intensity of the flame. [1]. Two the combustion numerical using chemical reaction mechanism involving HO2 intermediate reaction, the study confirmed that HO2 is a key intermediate, plays a decisive role to trigger early response, on afterburning temperature and flow concentration distribution effect. A finite rate chemical reaction model is used to describe the two burning phenomenon in high temperature plume[2]. In this paper, a numerical simulation of the flame flow field and radiative transfer is carried out for the afterburning phenomenon. The effects of afterburning on the composition, temperature and infrared radiation of the plume are obtained by comparison.

  14. Plume tectonics – myth or reality?

    Directory of Open Access Journals (Sweden)

    Ю. И. Дараган-Сущов

    2017-03-01

    Full Text Available The paper is dedicated to the role of mantle plumes in the formation of large igneous provinces. From different regions of the world facts are mentioned that contradict key points of plume tectonics. Closer attention is paid to classical volcanic provinces on Hawaiian islands and in Iceland, as well as to Siberian and Deccan Traps, oceanic plateau Ontong Java, Central Atlantic magmatic province, Alfa and Mendeleev Ridges in the Arctic Ocean. A conclusion is drawn that plumes are a special case of mantle-lithospheric flows, which according to deep geophysics are often located horizontally which leaves out their plume origin. Heated masses of mantle substance under young volcanic regions or rift zones of mid-ocean ridges do not emerge from the depth in the form of a straight column, but rather have arbitrary shapes, skewing to the sides and having outgrowths, offshoots, spherical bulges. Vertically rising flows of hot magma (plumes are not a cause, but an effect of a lithospheric split and rise of magmatic substance due to decompression. A conclusion is made that it is unproductive to exaggerate the shapes and sizes of plumes and use them to explain all the diversity of endogenous processes.

  15. Hubble Captures Volcanic Eruption Plume From Io

    Science.gov (United States)

    1997-01-01

    The Hubble Space Telescope has snapped a picture of a 400-km-high (250-mile-high) plume of gas and dust from a volcanic eruption on Io, Jupiter's large innermost moon.Io was passing in front of Jupiter when this image was taken by the Wide Field and Planetary Camera 2 in July 1996. The plume appears as an orange patch just off the edge of Io in the eight o'clock position, against the blue background of Jupiter's clouds. Io's volcanic eruptions blasts material hundreds of kilometers into space in giant plumes of gas and dust. In this image, material must have been blown out of the volcano at more than 2,000 mph to form a plume of this size, which is the largest yet seen on Io.Until now, these plumes have only been seen by spacecraft near Jupiter, and their detection from the Earth-orbiting Hubble Space Telescope opens up new opportunities for long-term studies of these remarkable phenomena.The plume seen here is from Pele, one of Io's most powerful volcanos. Pele's eruptions have been seen before. In March 1979, the Voyager 1 spacecraft recorded a 300-km-high eruption cloud from Pele. But the volcano was inactive when the Voyager 2 spacecraft flew by Jupiter in July 1979. This Hubble observation is the first glimpse of a Pele eruption plume since the Voyager expeditions.Io's volcanic plumes are much taller than those produced by terrestrial volcanos because of a combination of factors. The moon's thin atmosphere offers no resistance to the expanding volcanic gases; its weak gravity (one-sixth that of Earth) allows material to climb higher before falling; and its biggest volcanos are more powerful than most of Earth's volcanos.This image is a contrast-enhanced composite of an ultraviolet image (2600 Angstrom wavelength), shown in blue, and a violet image (4100 Angstrom wavelength), shown in orange. The orange color probably occurs because of the absorption and/or scattering of ultraviolet light in the plume. This light from Jupiter passes through the plume and is

  16. Pele Plume Deposit on Io

    Science.gov (United States)

    1997-01-01

    The varied effects of Ionian volcanism can be seen in this false color infrared composite image of Io's trailing hemisphere. Low resolution color data from Galileo's first orbit (June, 1996) have been combined with a higher resolution clear filter picture taken on the third orbit (November, 1996) of the spacecraft around Jupiter.A diffuse ring of bright red material encircles Pele, the site of an ongoing, high velocity volcanic eruption. Pele's plume is nearly invisible, except in back-lit photographs, but its deposits indicate energetic ejection of sulfurous materials out to distances more than 600 kilometers from the central vent. Another bright red deposit lies adjacent to Marduk, also a currently active ediface. High temperature hot spots have been detected at both these locations, due to the eruption of molten material in lava flows or lava lakes. Bright red deposits on Io darken and disappear within years or decades of deposition, so the presence of bright red materials marks the sites of recent volcanism.This composite was created from data obtained by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft. The region imaged is centered on 15 degrees South, 224 degrees West, and is almost 2400 kilometers across. The finest details that can be discerned in this picture are about 3 kilometers across. North is towards the top of the picture and the sun illuminates the surface from the west.The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  17. Microbial populations in contaminant plumes

    Science.gov (United States)

    Haack, Sheridan K.; Bekins, Barbara A.

    Efficient biodegradation of subsurface contaminants requires two elements: (1) microbial populations with the necessary degradative capabilities, and (2) favorable subsurface geochemical and hydrological conditions. Practical constraints on experimental design and interpretation in both the hydrogeological and microbiological sciences have resulted in limited knowledge of the interaction between hydrogeological and microbiological features of subsurface environments. These practical constraints include: (1) inconsistencies between the scales of investigation in the hydrogeological and microbiological sciences, and (2) practical limitations on the ability to accurately define microbial populations in environmental samples. However, advances in application of small-scale sampling methods and interdisciplinary approaches to site investigations are beginning to significantly improve understanding of hydrogeological and microbiological interactions. Likewise, culture-based and molecular analyses of microbial populations in subsurface contaminant plumes have revealed significant adaptation of microbial populations to plume environmental conditions. Results of recent studies suggest that variability in subsurface geochemical and hydrological conditions significantly influences subsurface microbial-community structure. Combined investigations of site conditions and microbial-community structure provide the knowledge needed to understand interactions between subsurface microbial populations, plume geochemistry, and contaminant biodegradation. La biodégradation efficace des polluants souterrains requiert deux éléments: des populations microbiennes possédant les aptitudes nécessaires à la dégradation, et des conditions géochimiques et hydrologiques souterraines favorables. Des contraintes pratiques sur la conception et l'interprétation des expériences à la fois en microbiologie et en hydrogéologie ont conduit à une connaissance limitée des interactions entre les

  18. PlumeSat: A Micro-Satellite Based Plume Imagery Collection Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ledebuhr, A.G.; Ng, L.C.

    2002-06-30

    This paper describes a technical approach to cost-effectively collect plume imagery of boosting targets using a novel micro-satellite based platform operating in low earth orbit (LEO). The plume collection Micro-satellite or PlueSat for short, will be capable of carrying an array of multi-spectral (UV through LWIR) passive and active (Imaging LADAR) sensors and maneuvering with a lateral divert propulsion system to different observation altitudes (100 to 300 km) and different closing geometries to achieve a range of aspect angles (15 to 60 degrees) in order to simulate a variety of boost phase intercept missions. The PlumeSat will be a cost effective platform to collect boost phase plume imagery from within 1 to 10 km ranges, resulting in 0.1 to 1 meter resolution imagery of a variety of potential target missiles with a goal of demonstrating reliable plume-to-hardbody handover algorithms for future boost phase intercept missions. Once deployed on orbit, the PlumeSat would perform a series phenomenology collection experiments until expends its on-board propellants. The baseline PlumeSat concept is sized to provide from 5 to 7 separate fly by data collects of boosting targets. The total number of data collects will depend on the orbital basing altitude and the accuracy in delivering the boosting target vehicle to the nominal PlumeSat fly-by volume.

  19. Resolving the Mantle Plume Heat Transfer Discrepancy

    Science.gov (United States)

    Hoggard, M.; Parnell-Turner, R. E.; White, N.

    2016-12-01

    Estimates of the buoyancy and heat flux of upwelling mantle plumes are important for understanding many aspects of convection within the Earth. These fluxes influence melt productivity and geochemistry at mid-oceanic spreading centres and hotspots, dynamic topography, mantle mixing timescales and Earth's bulk heat budget. The majority of existing plume flux estimates are calculated from the cross-sectional area of swells multiplied by either plate velocities or spreading rates. Hawaii and the other Pacific hotspots dominate these estimates, which indicate a total heat flux carried by plumes to the base of plates at ˜ 2 TW. Here, we use an alternative approach that calculates buoyancy flux using the swell volume constrained from a new map of dynamic topography, scaled by a characteristic swell decay time. This method avoids the assumption that plume material moves at or below the velocity of the overriding plate. Our results indicate that the Icelandic plume has a buoyancy flux of ˜ 27 ± 4 Mg/s , which is significantly larger than the Hawaiian plume and an order of magnitude greater than some previous estimates. These new values match independent geophysical constraints from Hawaii and the North Atlantic Ocean. All magmatic and amagmatic swells have been included in our global analysis, which reveals a total heat flux carried to the base of the plates of ˜ 10 ± 2 TW. This increased global heat flux is consistent with recent global seismic tomographic images of large upwelling plumes in the mid-mantle and predictions of heat flux through the core-mantle boundary.

  20. The hydrothermal outflow plume of Valles Caldera, New Mexico, and a comparison with other outflow plumes

    Science.gov (United States)

    Goff, Fraser; Shevenell, Lisa; Gardner, Jamie N.; Vuataz, Francois-D.; Grigsby, Charles O.

    1988-06-01

    Stratigraphic, temperature gradient, hydrogeochemical, and hydrologic data have been integrated with geologic data from previous studies to show the structural configuration of the Valles caldera hydrothermal ouflow plume. Hydrologic data suggest that 25-50% of the discharge of the Valles outflow is confined to the Jemez fault zone, which predates caldera formation. Thermal gradient data from bores penetrating the plume show that shallow gradients are highest in the vicinity of the Jemez fault zone (up to 190°C/km). Shallow heat flow above the hydrothermal plume is as high as 500 mW m-2 near core hole VC-1 (Jemez fault zone) to 200 mW m-2 at Fenton Hill (Jemez Plateau). Chemical and isotopic data indicate that two source reservoirs within the caldera (Redondo Creek and Sulphur Springs reservoirs) are parents to mixed fluids flowing in the hydrothermal plume. However, isotopic data, borehole data, basic geology, and inverse relations between temperature and chloride content at major hot springs indicate that no single reservoir fluid and no single diluting fluid are involved in mixing. The Valles caldera hydrothermal plume is structurally dominated by lateral flow through a belt of vertical conduits (Jemez fault zone) that strike away from the source reservoir. Stratigraphically confined flow is present but dispersed over a wide area in relatively impermeable rocks. The Valles configuration is contrasted with the configuration of the hydrothermal plume at Roosevelt Hot Springs, which is dominated by lateral flow through a near-surface, widespread, permeable aquifer. Data from 12 other representative geothermal systems show that outflow plumes occur in a variety of magmatic and tectonic settings, have varying reservoir compositions, and have different flow characteristics. Although temperature reversals are commonly observed in wells penetrating outflow plumes, reversals are not observed in all plumes. Less information is available on the absolute age of

  1. Compressible plume dynamics in the transition zone

    Science.gov (United States)

    Bossmann, A. B.; Van Keken, P. E.; Ritsema, J. E.; Goes, S. D.

    2012-12-01

    Plumes rising from the deep mantle may explain hotspot volcanism, but their occurrence in the lower mantle is not unambiguously confirmed by seismological imaging studies. Additionally, the seismologically observed flat topography of the 670 km discontinuity below hotspots disagrees with the elevation expected due to its negative Clapeyron slope and plume excess temperature. Numerical models that account for realistic rheology, compressibility and consistently implemented phase transitions may help reconciling these observations with the mantle plume hypothesis. Here we present numerical mantle plume models in an axisymmetric spherical shell geometry. The Anelastic Liquid Approximation is applied to the governing equations to account for mantle compressibility, viscous dissipation and work done against gravity. Besides this, a depth- and temperature dependent viscosity and the main phase boundaries at 400 and 670 km depth as well as latent heat effects during the phase transitions are considered. The reference state is based on the Birch-Murnaghan equation of state and considers PREM-like density jumps at 400 and 670 km depth and latent heat effects in the temperature profile. We include a dense layer above the core-mantle boundary from which the plume rises. Plume dynamics and morphology is studied for varying Clapeyron slope, especially at the endothermic phase transition, Rayleigh number and different viscosity models. We evaluate the importance of consistently implementing latent heat in the governing equations and reference state. Furthermore we vary excess density and thickness of the dense layer to study the effects on entrainment of the layer and the dynamics in the transition zone. Our models show that the seismologically observed flat topography of the 670 km phase boundary is consistent with a plume origin in the deep mantle and offer an additional explanation independent of previously proposed ones, as we observe a large plume head in the lower mantle

  2. CALIOP-derived Smoke Plume Injection Height

    Science.gov (United States)

    Soja, A. J.; Winker, D. M.; Choi, H. D.; Fairlie, T. D.; Westberg, D. J.; Roller, C. M.; Pouliot, G.; Vaughan, M.; Pierce, T. E.; Trepte, C. R.; Rao, V.

    2014-12-01

    Biomass burning is a dominant natural and anthropogenic disturbance that feeds back to the climate system. Fire regimes, ecosystem fuels, fire severity and intensity vary widely, even within the same system, largely under the control of weather and climate. These strongly influence fire plume injection height and thus the transport of related biomass burning emissions, affecting air quality, human health and the climate system. If our knowledge of plume injection height is incorrect, transport models of those emissions will likewise be incorrect, adversely affecting our ability to analyze and predict climate feedbacks (i.e. black carbon to the Arctic, precipitation, cloud-radiation relationships) and public health (air quality forecast). Historically, plume height was based on the pioneering work of G.A. Briggs [1969; 1971] and verified with limited field campaigns. However, we currently have two satellite instruments, Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) onboard CALIPSO (afternoon overpass) and Multi-angle Imaging SpectroRadiometer (MISR) onboard TERRA (morning overpass), that can provide the statistics necessary to verify our assumptions and improve fire plume injection height estimates for use in both small- and large-scale models. We have developed a methodology to assess fire plume injection height using the Langley Trajectory Model (LaTM), CALIOP, Hazard Mapping System (HMS) smoke plume, and MODerate Resolution Imaging Spectrometer (MODIS) thermal anomaly data that is capable of generating two distinct types of verification data. A single CALIOP smoke-filled aerosol envelop can be traced back to numerous fire events, and using multiple CALIOP transects from numerous days, a daily smoke plume injection height evolution from a single fire can be defined. Additionally, we have linked the smoke plumes to ecosystems and the meteorological variables that define fire weather. In concert, CALIOP and MISR data can produce the statistical knowledge

  3. Reconnaissance of gas plumes offshore Sado Island

    Science.gov (United States)

    Fukuoka, H.; Aoyama, C.; Watanabe, H.; Komatsu, H.; Tajima, H.

    2016-12-01

    In late March 2016, an exploration of gas plume offshore Sado Island was conducted to know about their distribution, especially from shallow sea floor of 150 - 400 m. In the Japan Sea, more than thousand of gas plumes had been found in the recent 3 years. Most of them are supposed to be originated from dissolution of submarine methane hydrate on the sea floor surface and/or shallow subsurface. Comparison of the plumes and flux observed by multi-beam sonar and fish-finder record between 2016 and 2013 shows that both of the distribution and the gas flux, evaluated from intensity in echogram has changed. Sub-bottom scanner imagery suggest that the apparently sub-surface gas-chimney-like structure was observed at as many sites. Unlike large-scale seafloor surface type methane-hydrate site, those subsurface chimney did not reach the seafloor, possibly because the temperature-pressure condition was not satisfied on the surface. Authors have sampled sea water near the vent of those plume gas, depressurized to extract dissolved air bubbles, which was subjected to chemical analysis. Atmospheres around above large-scale plume which looks reaching to the sea surface was collected and analyzed. Results show that the air collected from the seafloor near the vent contains slightly higher concentration of methane (CH4) and carbon dioxide (CO2).

  4. The 2016 Case for Mantle Plumes and a Plume-Fed Asthenosphere (Augustus Love Medal Lecture)

    Science.gov (United States)

    Morgan, Jason P.

    2016-04-01

    The process of science always returns to weighing evidence and arguments for and against a given hypothesis. As hypotheses can only be falsified, never universally proved, doubt and skepticism remain essential elements of the scientific method. In the past decade, even the hypothesis that mantle plumes exist as upwelling currents in the convecting mantle has been subject to intense scrutiny; from geochemists and geochronologists concerned that idealized plume models could not fit many details of their observations, and from seismologists concerned that mantle plumes can sometimes not be 'seen' in their increasingly high-resolution tomographic images of the mantle. In the place of mantle plumes, various locally specific and largely non-predictive hypotheses have been proposed to explain the origins of non-plate boundary volcanism at Hawaii, Samoa, etc. In my opinion, this debate has now passed from what was initially an extremely useful restorative from simply 'believing' in the idealized conventional mantle plume/hotspot scenario to becoming an active impediment to our community's ability to better understand the dynamics of the solid Earth. Having no working hypothesis at all is usually worse for making progress than having an imperfect and incomplete but partially correct one. There continues to be strong arguments and strong emerging evidence for deep mantle plumes. Furthermore, deep thermal plumes should exist in a mantle that is heated at its base, and the existence of Earth's (convective) geodynamo clearly indicates that heat flows from the core to heat the mantle's base. Here I review recent seismic evidence by French, Romanowicz, and coworkers that I feel lends strong new observational support for the existence of deep mantle plumes. I also review recent evidence consistent with the idea that secular core cooling replenishes half the mantle's heat loss through its top surface, e.g. that the present-day mantle is strongly bottom heated. Causes for

  5. A new way to detect volcanic plumes

    Science.gov (United States)

    Larson, Kristine M.

    2013-06-01

    of volcanic plumes, especially ash-laden ones, is important both for public health and aircraft safety. A variety of geophysical tools and satellite data are used to monitor volcanic eruptions and to predict the movement of ash. However, satellite-based methods are restricted by time of day and weather, while radars are often unavailable because of cost/portability. Here a method is proposed to detect volcanic plumes using GPS signal strength data. The strengths and limitations of the method are assessed using GPS data collected during the 2008 and 2009 eruptions of the Okmok and Mt. Redoubt volcanoes. Plume detections using this GPS technique are consistent with independently collected seismic and radar data.

  6. Numerical and approximate solutions for plume rise

    Science.gov (United States)

    Krishnamurthy, Ramesh; Gordon Hall, J.

    Numerical and approximate analytical solutions are compared for turbulent plume rise in a crosswind. The numerical solutions were calculated using the plume rise model of Hoult, Fay and Forney (1969, J. Air Pollut. Control Ass.19, 585-590), over a wide range of pertinent parameters. Some wind shear and elevated inversion effects are included. The numerical solutions are seen to agree with the approximate solutions over a fairly wide range of the parameters. For the conditions considered in the study, wind shear effects are seen to be quite small. A limited study was made of the penetration of elevated inversions by plumes. The results indicate the adequacy of a simple criterion proposed by Briggs (1969, AEC Critical Review Series, USAEC Division of Technical Information extension, Oak Ridge, Tennesse).

  7. Properties of industrial dense gas plumes

    Science.gov (United States)

    Shaver, E. M.; Forney, L. J.

    Hazardous gases and vapors are often discharged into the atmosphere from industrial plants during catastrophic events (e.g. Union Carbide incident in Bhopal, India). In many cases the discharged components are more dense than air and settle to the ground surface downstream from the stack exit. In the present paper, the buoyant plume model of Hoult, Fay and Forney (1969, J. Air Pollut. Control Ass. 19, 585-590.) has been altered to predict the properties of hazardous discharges. In particular, the plume impingement point, radius and concentration are predicted for typical stack exit conditions, wind speeds and temperature profiles. Asymptotic expressions for plume properties at the impingement point are also derived for a constant crosswind and neutral temperature profile. These formulae are shown to be useful for all conditions.

  8. A collisionless plasma thruster plume expansion model

    Science.gov (United States)

    Merino, Mario; Cichocki, Filippo; Ahedo, Eduardo

    2015-06-01

    A two-fluid model of the unmagnetized, collisionless far region expansion of the plasma plume for gridded ion thrusters and Hall effect thrusters is presented. The model is integrated into two semi-analytical solutions valid in the hypersonic case. These solutions are discussed and compared against the results from the (exact) method of characteristics; the relative errors in density and velocity increase slowly axially and radially and are of the order of 10-2-10-3 in the cases studied. The plasma density, ion flux and ambipolar electric field are investigated. A sensitivity analysis of the problem parameters and initial conditions is carried out in order to characterize the far plume divergence angle in the range of interest for space electric propulsion. A qualitative discussion of the physics of the secondary plasma plume is also provided.

  9. Enceladus Plumes: A Boiling Liquid Model

    Science.gov (United States)

    Nakajima, Miki; Ingersoll, A. P.

    2012-10-01

    Following the discovery of H2O vapor and particle plumes from the tiger stripes at the south pole of Enceladus (Porco et al., 2006), observational and theoretical studies have been conducted to understand the plume mechanism (e.g., Schmidt et al., 2008; Kieffer et al., 2009; Ingersoll and Pankine, 2010). Although the “Ice Chamber Model”, which assumes that ice sublimation under the stripes causes the plumes, has successfully explained the plume mass flux (e.g., Nimmo et al., 2007; Ingersoll and Pankine, 2010), it cannot explain the high salinity in the plume (Postberg et al., 2009). Ice particles condensing from a vapor are relatively salt free, but ice particles derived from a salty liquid can have high salinity. Therefore we have investigated the “Boiling Liquid Model”, which assumes that liquid H2O under the stripes causes the plumes. With conservation of mass, momentum and energy, we built a simple atmospheric model that includes controlled boiling and gas-ice wall interaction. We first assumed that the heat radiated to space comes entirely from the heat generated by condensation of the gas onto the ice wall. We varied the width (0.1-1 m) and the height (5-4000 m) of the crack as parameters. We find that the escaping vapor flux can be relatively close to the observed value (250±100 kg/s, Hansen et al., 2006, 2008) but the radiated heat flux is only 1 GW, which is much less than the observed value (15.8 GW, Howett et al., 2011). Other models (Nimmo et al., 2007; Abramov and Spencer, 2009) also have the same difficulty accounting for the observed value. We then investigated the additional heat radiated by the particles after they come out of the crack. We built a simple model to estimate the size distributions of these condensed ice particles and their radiative properties.

  10. Halogen Chemistry in Volcanic Plumes (Invited)

    Science.gov (United States)

    Roberts, Tjarda

    2017-04-01

    Volcanoes release vast amounts of gases and particles in the atmosphere. Volcanic halogens (HF, HCl, HBr, HI) are co-emitted alongside SO2, and observations show rapid formation of BrO and OClO in the plume as it disperses into the troposphere. The development of 1D and Box models (e.g. PlumeChem) that simulate volcanic plume halogen chemistry aims to characterise how volcanic reactive halogens form and quantify their atmospheric impacts. Following recent advances, these models can broadly reproduce the observed downwind BrO/SO2 ratios using "bromine-explosion" chemistry schemes, provided they use a "high-temperature initialisation" to inject radicals (OH, Cl, Br and possibly NOx) which "kick-start" the low-temperature chemistry cycles that convert HBr into reactive bromine (initially as Br2). The modelled rise in BrO/SO2 and subsequent plateau/decline as the plume disperses downwind reflects cycling between reactive bromine, particularly Br-BrO, and BrO-HOBr-BrONO2. BrCl is produced when aerosol becomes HBr-depleted. Recent model simulations suggest this mechanism for reactive chlorine formation can broadly account for OClO/SO2 reported at Mt Etna. Predicted impacts of volcanic reactive halogen chemistry include the formation of HNO3 from NOx and depletion of ozone. This concurs with HNO3 widely reported in volcanic plumes (although the source of NOx remains under question), as well as observations of ozone depletion reported in plumes from several volcanoes (Mt Redoubt, Mt Etna, Eyjafjallajokull). The plume chemistry can transform mercury into more easily deposited and potentially toxic forms, for which observations are limited. Recent incorporation of volcanic halogen chemistry in a 3D regional model of degassing from Ambrym (Vanuatu) also predicts how halogen chemistry causes depletion of OH to lengthen the SO2 lifetime, and highlights the potential for halogen transport from the troposphere to the stratosphere. However, the model parameter-space is vast and

  11. Infrared measurements of launch vehicle exhaust plumes

    Science.gov (United States)

    Schweitzer, Caroline; Ohmer, Phillip; Wendelstein, Norbert; Stein, Karin

    2017-10-01

    In the fields of early warning, one is depending on reliable analytical models for the prediction of the infrared threat signature: By having this as a basis, the warning sensors can be specified as suitable as possible to give timely threat approach alerts. In this paper, we will present preliminary results of measurement trials that have been carried out in 2015, where the exhaust plume of launch vehicles has been measured under various atmospheric conditions. The gathered data will be used to validate analytical models for the prediction of the plume signature.

  12. Scaling for turbulent viscosity of buoyant plumes in stratified fluids: PIV measurement with implications for submarine hydrothermal plume turbulence

    Science.gov (United States)

    Zhang, Wei; He, Zhiguo; Jiang, Houshuo

    2017-11-01

    Time-resolved particle image velocimetry (PIV) has been used to measure instantaneous two-dimensional velocity vector fields of laboratory-generated turbulent buoyant plumes in linearly stratified saltwater over extended periods of time. From PIV-measured time-series flow data, characteristics of plume mean flow and turbulence have been quantified. To be specific, maximum plume penetration scaling and entrainment coefficient determined from the mean flow agree well with the theory based on the entrainment hypothesis for buoyant plumes in stratified fluids. Besides the well-known persistent entrainment along the plume stem (i.e., the 'plume-stem' entrainment), the mean plume velocity field shows persistent entrainment along the outer edge of the plume cap (i.e., the 'plume-cap' entrainment), thereby confirming predictions from previous numerical simulation studies. To our knowledge, the present PIV investigation provides the first measured flow field data in the plume cap region. As to measured plume turbulence, both the turbulent kinetic energy field and the turbulence dissipation rate field attain their maximum close to the source, while the turbulent viscosity field reaches its maximum within the plume cap region; the results also show that maximum turbulent viscosity scales as νt,max = 0.030(B/N)1/2, where B is source buoyancy flux and N is ambient buoyancy frequency. These PIV data combined with previously published numerical simulation results have implications for understanding the roles of hydrothermal plume turbulence, i.e. plume turbulence within the cap region causes the 'plume-cap' entrainment that plays an equally important role as the 'plume-stem' entrainment in supplying the final volume flux at the plume spreading level.

  13. Tracking Iceland Plume Motion Using Trace Element Geochemistry

    Science.gov (United States)

    Fitton, J. G.; Walters, R. L.; Jones, S. M.

    2011-12-01

    The Greenland-Scotland Ridge (GSR) is a hotspot track built by interaction between the Mid Atlantic Ridge (MAR) and the Iceland mantle plume. Unlike most other hotspot tracks built by ridge-plume interaction, the GSR is 2 to 3 times wider than the plume conduit in the upper mantle. (This unusual wide morphology arises because Icelandic crust changes significantly in thickness within a few million years of accretion, probably mainly by viscous flow in the hot lower crust). The upshot is that the GSR cannot be compared directly with theoretical plume tracks from hotspot reference frame models. However, it is possible to track the position of the Iceland plume conduit using the trace element geochemistry of basaltic lavas. Away from the plume conduit, plate spreading drives upwelling of mantle through the melting region. Above the plume conduit, plume-driven flow forces mantle through the lower part of the melting region faster than the plate-driven upwelling rate. The average depth of melting is therefore greater directly above the plume conduit than away from the plume conduit, and this difference in average melting depth means that melts generated directly above the plume conduit are relatively enriched in incompatible trace elements. Joint modelling of trace element compositions and crustal thickness can also be used to establish location of melting relative to the plume conduit. To date, these concepts have been used only to explain compositional variations in modern (post-glacial) Icelandic lavas; in this study we show that the same concepts can be applied to map the location of the plume conduit throughout the onshore Icelandic geological record (since the middle Miocene, c. 16 Ma). The plume track thus determined is in reasonable agreement with theoretical tracks calculated under the assumption that the Iceland Plume has remained fixed relative to other Indo-Atlantic hotspots. This result also supports the idea that episodic relocations of the onshore part of

  14. Characterization of redox conditions in groundwater contaminant plumes

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Bjerg, Poul Løgstrup; Banwarth, Steven A.

    2000-01-01

    Evaluation of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behaviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few...... dubious, if not erroneous. Several other approaches have been used in addressing redox conditions in pollution plumes: redox-sensitive compounds in groundwater samples, hydrogen concentrations in groundwater, concentrations of volatile fatty acids in groundwater, sediment characteristics and microbial...

  15. Merging Thermal Plumes in the Indoor Environment

    DEFF Research Database (Denmark)

    Bjørn, Erik; Nielsen, Peter V.

    This experimental work deals with the basic problem of merging thermal plumes from heat sources situated in the vicinity of each other. No studies have been made yet of how close two heat sources must be to each other, before they can be considered as a single source with a cumulative heat effect...

  16. Plume dynamics in heterogeneous porous media

    Science.gov (United States)

    Neufeld, Jerome A.; Huppert, Herbert E.

    2008-11-01

    Buoyancy driven flows in layered porous media are present in many geological settings and play an important role in the mixing of fluids, from the dispersal of pollutants in underground aquifers to enhanced oil recovery techniques and, of more recent importance, the sequestration of carbon dioxide (CO2). Seismic images of the rise of a buoyant CO2 plume at Sleipner in the North Sea indicate that these plumes are greatly influenced by a vertical array of thin lenses of relatively low permeability material. We model propagation of CO2 at each layer as a gravity current in a porous medium which propagates along, and drains through, a thin, low permeability seal. Drainage, driven both by hydrostatic pressure and the body force on the draining fluid, leads to an initial rapid advance followed by a gradual retreat of the current to a steady-state. By incorporating a vertical array of these single layer models we are able to capture the rise of the buoyant plume in layered reservoirs. We find that the plume is characterized by a broad head with a tail given by the steady state extent.

  17. Near field characteristics of buoyant helium plumes

    Indian Academy of Sciences (India)

    affects the combustion. Puffing is also observed in low density gas plumes when the ratio of inlet ... generated using helium and helium–air mixtures, hot gases were used to understand the flow dynamics associated .... The glass lens acts as a filter to block any UV light and prevents fluorescence signal contamination. Since.

  18. Near field characteristics of buoyant helium plumes

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Sadhana; Volume 40; Issue 3. Near field characteristics of buoyant helium plumes. Kuchimanchi K Bharadwaj Debopam Das Pavan K Sharma. Section I – Fluid Mechanics and Fluid Power (FMFP) Volume 40 Issue 3 May 2015 pp 757- ...

  19. Characterization and Modeling of Plumes and Animal Plume-Tracing in Wave-Influenced Coastal Environments

    National Research Council Canada - National Science Library

    Koseff, Jeffrey

    2002-01-01

    .... ensigera in unidirectional and wave-influenced flow environments, and correlated tracing maneuvers with the simultaneously-recorded characteristics of the odor plume at the position of the animals' olfactory antennules...

  20. Representative Atmospheric Plume Development for Elevated Releases

    Energy Technology Data Exchange (ETDEWEB)

    Eslinger, Paul W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lowrey, Justin D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McIntyre, Justin I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Miley, Harry S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Prichard, Andrew W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-02-01

    An atmospheric explosion of a low-yield nuclear device will produce a large number of radioactive isotopes, some of which can be measured with airborne detection systems. However, properly equipped aircraft may not arrive in the region where an explosion occurred for a number of hours after the event. Atmospheric conditions will have caused the radioactive plume to move and diffuse before the aircraft arrives. The science behind predicting atmospheric plume movement has advanced enough that the location of the maximum concentrations in the plume can be determined reasonably accurately in real time, or near real time. Given the assumption that an aircraft can follow a plume, this study addresses the amount of atmospheric dilution expected to occur in a representative plume as a function of time past the release event. The approach models atmospheric transport of hypothetical releases from a single location for every day in a year using the publically available HYSPLIT code. The effective dilution factors for the point of maximum concentration in an elevated plume based on a release of a non-decaying, non-depositing tracer can vary by orders of magnitude depending on the day of the release, even for the same number of hours after the release event. However, the median of the dilution factors based on releases for 365 consecutive days at one site follows a power law relationship in time, as shown in Figure S-1. The relationship is good enough to provide a general rule of thumb for estimating typical future dilution factors in a plume starting at the same point. However, the coefficients of the power law function may vary for different release point locations. Radioactive decay causes the effective dilution factors to decrease more quickly with the time past the release event than the dilution factors based on a non-decaying tracer. An analytical expression for the dilution factors of isotopes with different half-lives can be developed given the power law expression

  1. The thin hot plume beneath Iceland

    Science.gov (United States)

    Allen, R.M.; Nolet, G.; Morgan, W.J.; Vogfjord, K.; Bergsson, B.H.; Erlendsson, P.; Foulger, G.R.; Jakobsdottir, S.; Julian, B.R.; Pritchard, M.; Ragnarsson, S.; Stefansson, R.

    1999-01-01

    We present the results of a seismological investigation of the frequency-dependent amplitude variations across Iceland using data from the HOTSPOT array currently deployed there. The array is composed of 30 broad-band PASSCAL instruments. We use the parameter t(*), defined in the usual manner from spectral ratios (Halderman and Davis 1991), to compare observed S-wave amplitude variations with those predicted due to both anelastic attenuation and diffraction effects. Four teleseismic events at a range of azimuths are used to measure t(*). A 2-D vertical cylindrical plume model with a Gaussian-shaped velocity anomaly is used to model the variations. That part of t(*) caused by attenuation was estimated by tracing a ray through IASP91, then superimposing our plume model velocity anomaly and calculating the path integral of 1/vQ. That part of t(*) caused by diffraction was estimated using a 2-D finite difference code to generate synthetic seismograms. The same spectral ratio technique used for the data was then used to extract a predicted t(*). The t(*) variations caused by anelastic attenuation are unable to account for the variations we observe, but those caused by diffraction do. We calculate the t(*) variations caused by diffraction for different plume models and obtain our best-fit plume, which exhibits good agreement between the observed and measured t(*). The best-fit plume model has a maximum S-velocity anomaly of - 12 per cent and falls to 1/e of its maximum at 100 km from the plume centre. This is narrower than previous estimates from seismic tomography, which are broadened and damped by the methods of tomography. This velocity model would suggest greater ray theoretical traveltime delays than observed. However, we find that for such a plume, wave-front healing effects at frequencies of 0.03-0.175 Hz (the frequency range used to pick S-wave arrivals) causes a 40 per cent reduction in traveltime delay, reducing the ray theoretical delay to that observed.

  2. Segregation of acid plume pixels from background water pixels, signatures of background water and dispersed acid plumes, and implications for calculation of iron concentration in dense plumes

    Science.gov (United States)

    Bahn, G. S.

    1978-01-01

    Two files of data, obtained with a modular multiband scanner, for an acid waste dump into ocean water, were analyzed intensively. Signatures were derived for background water at different levels of effective sunlight intensity, and for different iron concentrations in the dispersed plume from the dump. The effect of increased sunlight intensity on the calculated iron concentration was found to be relatively important at low iron concentrations and relatively unimportant at high values of iron concentration in dispersed plumes. It was concluded that the basic equation for iron concentration is not applicable to dense plumes, particularly because lower values are indicated at the very core of the plume, than in the surrounding sheath, whereas radiances increase consistently from background water to dispersed plume to inner sheath to innermost core. It was likewise concluded that in the dense plume the iron concentration would probably best be measured by the higher wave length radiances, although the suitable relationship remains unknown.

  3. Summertime Changjiang River plume variation during 1998-2010

    Science.gov (United States)

    Bai, Yan; He, Xianqiang; Pan, Delu; Chen, Chen-Tung Arthur; Kang, Yan; Chen, Xiaoyan; Cai, Wei-Jun

    2014-09-01

    Using an improved satellite-derived salinity algorithm in the East China Sea (ECS), we presented and examined a general view on summertime Changjiang River plume variation during 1998-2010. Three types of plume shapes were identified: (1) the commonly known northeastward transportation, (2) a case in which most of the plume water crossed the Cheju Strait into the Tsushima-Korea Straits with only a small fraction staying on the shelf of the ECS, and (3) a rare case in which the plume front moved southeastward. Satellite time-series data suggested that, during the peak river discharge time in July with favorable southwest monsoon, the plume area was highly correlated with the river discharge of the same month. Interestingly, the plume area in August was also dominated by the discharge in July. In August, as the direct effect of freshwater discharge weakening, the plume area also became positively correlated with wind speed in the 45° and 60°direction, suggesting that the plume extension was more influenced by the southwesterly wind during periods of smaller discharge. Furthermore, a few special cases with unique plume extensions were found under extreme weather conditions. Finally, we found no significant long-term trend of plume area change over 1998-2010 in summertime and concluded that the interannual variation was probably regulated by natural variation rather than anthropogenic effects, such as construction of the Three Gorges Dam. This study will have implications for biogeochemical and modeling studies in large river plume areas.

  4. On possible plume-guided seismic waves

    Science.gov (United States)

    Julian, B.R.; Evans, J.R.

    2010-01-01

    Hypothetical thermal plumes in the Earth's mantle are expected to have low seismic-wave speeds and thus would support the propagation of guided elastic waves analogous to fault-zone guided seismic waves, fiber-optic waves, and acoustic waves in the oceanic SOund Fixing And Ranging channel. Plume-guided waves would be insensitive to geometric complexities in the wave guide, and their dispersion would make them distinctive on seismograms and would provide information about wave-guide structure that would complement seismic tomography. Detecting such waves would constitute strong evidence of a new kind for the existence of plumes. A cylindrical channel embedded in an infinite medium supports two classes of axially symmetric elastic-wave modes, torsional and longitudinal-radial. Torsional modes have rectilinear particle motion tangent to the cylinder surface. Longitudinal-radial modes have elliptical particle motion in planes that include the cylinder axis, with retrograde motion near the axis. The direction of elliptical particle motion reverses with distance from the axis: once for the fundamental mode, twice for the first overtone, and so on. Each mode exists only above its cut-off frequency, where the phase and group speeds equal the shear-wave speed in the infinite medium. At high frequencies, both speeds approach the shear-wave speed in the channel. All modes have minima in their group speeds, which produce Airy phases on seismograms. For shear wave-speed contrasts of a few percent, thought to be realistic for thermal plumes in the Earth, the largest signals are inversely dispersed and have dominant frequencies of about 0.1-1 Hz and durations of 15-30 sec. There are at least two possible sources of observable plume waves: (1) the intersection of mantle plumes with high-amplitude core-phase caustics in the deep mantle; and (2) ScS-like reflection at the core-mantle boundary of downward-propagating guided waves. The widespread recent deployment of broadband

  5. Electric Propulsion Plume Simulations Using Parallel Computer

    Directory of Open Access Journals (Sweden)

    Joseph Wang

    2007-01-01

    Full Text Available A parallel, three-dimensional electrostatic PIC code is developed for large-scale electric propulsion simulations using parallel supercomputers. This code uses a newly developed immersed-finite-element particle-in-cell (IFE-PIC algorithm designed to handle complex boundary conditions accurately while maintaining the computational speed of the standard PIC code. Domain decomposition is used in both field solve and particle push to divide the computation among processors. Two simulations studies are presented to demonstrate the capability of the code. The first is a full particle simulation of near-thruster plume using real ion to electron mass ratio. The second is a high-resolution simulation of multiple ion thruster plume interactions for a realistic spacecraft using a domain enclosing the entire solar array panel. Performance benchmarks show that the IFE-PIC achieves a high parallel efficiency of ≥ 90%

  6. Modeling contaminant plumes in fractured limestone aquifers

    DEFF Research Database (Denmark)

    Mosthaf, Klaus; Brauns, Bentje; Fjordbøge, Annika Sidelmann

    Determining the fate and transport of contaminant plumes from contaminated sites in limestone aquifers is important because they are a major drinking water resource. This is challenging because they are often heavily fractured and contain chert layers and nodules, resulting in a complex transport...... behavior. Improved conceptual models are needed for this type of site. Here conceptual models are developed by combining numerical models with field data. Several types of fracture flow and transport models are available for the modeling of contaminant transport in fractured media. These include...... the established approaches of the equivalent porous medium, discrete fracture and dual continuum models. However, these modeling concepts are not well tested for contaminant plume migration in limestone geologies. Our goal was to develop and evaluate approaches for modeling the transport of dissolved contaminant...

  7. Sub-Grid Scale Plume Modeling

    Directory of Open Access Journals (Sweden)

    Greg Yarwood

    2011-08-01

    Full Text Available Multi-pollutant chemical transport models (CTMs are being routinely used to predict the impacts of emission controls on the concentrations and deposition of primary and secondary pollutants. While these models have a fairly comprehensive treatment of the governing atmospheric processes, they are unable to correctly represent processes that occur at very fine scales, such as the near-source transport and chemistry of emissions from elevated point sources, because of their relatively coarse horizontal resolution. Several different approaches have been used to address this limitation, such as using fine grids, adaptive grids, hybrid modeling, or an embedded sub-grid scale plume model, i.e., plume-in-grid (PinG modeling. In this paper, we first discuss the relative merits of these various approaches used to resolve sub-grid scale effects in grid models, and then focus on PinG modeling which has been very effective in addressing the problems listed above. We start with a history and review of PinG modeling from its initial applications for ozone modeling in the Urban Airshed Model (UAM in the early 1980s using a relatively simple plume model, to more sophisticated and state-of-the-science plume models, that include a full treatment of gas-phase, aerosol, and cloud chemistry, embedded in contemporary models such as CMAQ, CAMx, and WRF-Chem. We present examples of some typical results from PinG modeling for a variety of applications, discuss the implications of PinG on model predictions of source attribution, and discuss possible future developments and applications for PinG modeling.

  8. Geodynamic modelling of low-buoyancy thermo-chemical plumes

    Science.gov (United States)

    Dannberg, Juliane; Sobolev, Stephan

    2015-04-01

    The Earth's biggest magmatic events that form Large Igneous Provinces are believed to originate from massive melting when hot mantle plumes rising from the lowermost mantle reach the base of the lithosphere. Classical models of thermal mantle plumes predict a flattening of the plume head to a disk-like structure, a kilometer-scale surface uplift just before the initiation of LIPs and thin plume tails. However, there are seismic observations and paleo-topography data that are difficult to explain with this classical approach. Here, using numerical models, we show that the issue can be resolved if major mantle plumes are thermo-chemical rather than purely thermal. It has been suggested a long time ago that subducted oceanic crust could be recycled by mantle plumes; and based on geochemical data, they may contain up to 15-20% of this recycled material in the form of dense eclogite, which drastically decreases their buoyancy and makes it depth-dependent. We perform numerical experiments in a 3D spherical shell geometry to investigate the dynamics of the plume ascent, the interaction between plume- and plate-driven flow and the dynamics of melting in a plume head. For this purpose, we use the finite-element code ASPECT, which allows for complex temperature-, pressure- and composition-dependent material properties. Moreover, our models incorporate phase transitions (including melting) with the accompanying rheological and density changes, Clapeyron slopes and latent heat effects for both peridotite and eclogite, mantle compressibility and a strong temperature- and depth-dependent viscosity. We demonstrate that despite their low buoyancy, such plumes can rise through the whole mantle causing only negligible surface uplift. Conditions for this ascent are high plume volume and moderate lower mantle subadiabaticity. While high plume buoyancy results in plumes directly advancing to the base of the lithosphere, plumes with slightly lower buoyancy pond in a depth of 300-400 km

  9. Anticyclonic precession of a plume in a rotating environment

    Science.gov (United States)

    Frank, D.; Landel, J. R.; Dalziel, S. B.; Linden, P. F.

    2017-09-01

    Motivated by potential effects of the Earth's rotation on the Deepwater Horizon oil plume, we conducted laboratory experiments on saltwater point plumes in a homogeneous rotating environment across a wide range of Rossby numbers 0.02≤Ro≤1.3. We report a striking physical instability in the plume dynamics near the source: after approximately one rotation period, the plume tilts laterally and starts to precess anticyclonically. The mean precession frequency ω¯ scales linearly with the rotation rate Ω as ω¯≈0.4Ω. We find no evidence of a critical Rossby number above which precession ceases. We infer that a conventionally defined Rossby number is not an appropriate parameter when the plume is maintained over a long time: provided Ω ≠ 0, rotation is always important to the dynamics. This indicates that precession may occur in persistent oceanic or atmospheric plumes even at low latitudes.

  10. Life Cycle of Mantle Plumes: A perspective from the Galapagos Plume (Invited)

    Science.gov (United States)

    Gazel, E.; Herzberg, C. T.

    2009-12-01

    Hotspots are localized sources of heat and magmatism considered as modern-day evidence of mantle plumes. Some hotspots are related to massive magmatic production that generated Large Igneous Provinces (LIPS), an initial-peak phase of plume activity with a mantle source hotter and more magmatically productive than present-day hotspots. Geological mapping and geochronological studies have shown much lower eruption rates for OIB compared to lavas from Large Igneous Provinces LIPS such as oceanic plateaus and continental flood provinces. Our study is the first quantitative petrological comparison of mantle source temperatures and extent of melting for OIB and LIP sources. The wide range of primary magma compositions and inferred mantle potential temperatures for each LIP and OIB occurrence suggest that this rocks originated form a hotspot, a spatially localized source of heat and magmatism restricted in time. Extensive outcrops of basalt, picrite, and sometimes komatiite with circa 65-95 Ma ages occupy portions of the pacific shore of Central and South America included in the Caribbean Large Igneous Province (CLIP). There is general consensus of a Pacific-origin of CLIP and most studies suggest that it was produced by melting in the Galapagos mantle plume. The Galapagos connection is consistent with isotopic and geochemical similarities with lavas from the present-day Galapagos hotspot. A Galapagos link for rocks in South American oceanic complexes (eg. the island of Gorgona) is more controversial and requires future work. The MgO and FeO contents of lavas from the Galapagos related lavas and their primary magmas have decreased since the Cretaceous. From petrological modeling we infer that these changes reflect a cooling of the Galapagos mantle plume from a potential temperature of 1560-1620 C in the Cretaceous to 1500 C at the present time. These temperatures are higher than 1350 C for ambient mantle associated with oceanic ridges, and provide support for the mantle

  11. Dynamic Data-Driven UAV Network for Plume Characterization

    Science.gov (United States)

    2016-05-23

    AFRL-AFOSR-VA-TR-2016-0203 Dynamic Data-Driven UAV Network for Plume Characterization Kamran Mohseni UNIVERSITY OF FLORIDA Final Report 05/23/2016...AND SUBTITLE Dynamic Data-Driven UAV Network for Plume Characterization 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-13-1-0090 5c.  PROGRAM ELEMENT...toxic plume characterization, Intelligence, Surveillance and Reconnaissance (ISR), environmental monitoring, weather forecasting, and disaster

  12. New method for calculation of integral characteristics of thermal plumes

    DEFF Research Database (Denmark)

    2008-01-01

    A method for calculation of integral characteristics of thermal plumes is proposed. The method allows for determination of the integral parameters of plumes based on speed measurements performed with omnidirectional low velocity thermoanemometers. The method includes a procedure for calculation...... occupant. The improvement in calculation of the characteristics of the thermal plume achieved with the developed method, in comparison with methods used and reported in the literature, is demonstrated....

  13. Marine bird aggregations associated with the tidally-driven plume and plume fronts of the Columbia River

    Science.gov (United States)

    Zamon, Jeannette E.; Phillips, Elizabeth M.; Guy, Troy J.

    2014-09-01

    Freshwater discharge from large rivers into the coastal ocean creates tidally-driven frontal systems known to enhance mixing, primary production, and secondary production. Many authors suggest that tidal plume fronts increase energy flow to fish-eating predators by attracting planktivorous fishes to feed on plankton aggregated by the fronts. However, few studies of plume fronts directly examine piscivorous predator response to plume fronts. Our work examined densities of piscivorous seabirds relative to the plume region and plume fronts of the Columbia River, USA. Common murres (Uria aalge) and sooty shearwaters (Puffinus griseus) composed 83% of all birds detected on mesoscale surveys of the Washington and Oregon coasts (June 2003-2006), and 91.3% of all birds detected on fine scale surveys of the plume region less than 40 km from the river mouth (May 2003 and 2006). Mesoscale comparisons showed consistently more predators in the central plume area compared to the surrounding marine area (murres: 10.1-21.5 vs. 3.4-8.2 birds km-2; shearwaters: 24.2-75.1 vs. 11.8-25.9 birds km-2). Fine scale comparisons showed that murre density in 2003 and shearwater density in both 2003 and 2006 were significantly elevated in the tidal plume region composed of the most recently discharged river water. Murres tended to be more abundant on the north face of the plume. In May 2003, more murres and shearwaters were found within 3 km of the front on any given transect, although maximum bird density was not necessarily found in the same location as the front itself. Predator density on a given transect was not correlated with frontal strength in either year. The high bird densities we observed associated with the tidal plume demonstrate that the turbid Columbia River plume does not necessarily provide fish with refuge from visual predators. Bird predation in the plume region may therefore impact early marine survival of Pacific salmon (Oncorhynchus spp.), which must migrate through the

  14. Exceptionally Long MTBE Plumes of the Past Have Greatly Diminished.

    Science.gov (United States)

    McDade, James M; Connor, John A; Paquette, Shawn M; Small, Julia M

    2015-01-01

    Studies published in the late 1990s and early 2000s identified the presence of exceptionally long methyl tert-butyl ether (MTBE) plumes (more than 600 m or 2000 feet) in groundwater and have been cited in technical literature as characteristic of MTBE plumes. However, the scientific literature is incomplete in regard to the subsequent behavior and fate of these MTBE plumes over the past decade. To address this gap, this issue paper compiles recent groundwater monitoring records for nine exceptional plumes that were identified in prior studies. These nine sites exhibited maximum historical MTBE groundwater plume lengths ranging from 820 m (2700 feet) to 3200 m (10,500 feet) in length, exceeding the lengths of 99% of MTBE plumes, as characterized in multiple surveys at underground storage tank sites across the United States. Groundwater monitoring data compiled in our review demonstrate that these MTBE plumes have decreased in length over the past decade, with five of the nine plumes exhibiting decreases of 75% or more compared to their historical maximum lengths. MTBE concentrations within these plumes have decreased by 93% to 100%, with two of the nine sites showing significant decreases (98% and 99%) such that the regulatory authority has subsequently designated the site as requiring no further action. © 2015 The Authors. Groundwater published by Wiley Periodicals,Inc. on behalf of National Ground Water Association.

  15. Quasi-periodic compressive waves in polar plumes

    Science.gov (United States)

    DeForest, C. E.; Gurman, J. B.

    1997-01-01

    The observation of polar plumes in the south polar coronal hole, carried out on 7 March 1996 by the Solar and Heliospheric Observatory (SOHO), are analyzed. These polar plumes are cool density structures that arise from morphologically unipolar magnetic footpoints. Data from the extreme ultraviolet imaging telescope show quasi-periodic perturbations in the brightness of the Fe IX and X line emissions at 171 A from polar plumes. The perturbations have periods of 10 to 15 min, and repeat for several cycles suggesting that they are compressive waves propagating through the plume at or near the Alfven speed. Possible explanations for the observed phenomenon are proposed.

  16. Algorithms and analysis for underwater vehicle plume tracing.

    Energy Technology Data Exchange (ETDEWEB)

    Byrne, Raymond Harry; Savage, Elizabeth L. (Texas A& M University, College Station, TX); Hurtado, John Edward (Texas A& M University, College Station, TX); Eskridge, Steven E.

    2003-07-01

    The goal of this research was to develop and demonstrate cooperative 3-D plume tracing algorithms for miniature autonomous underwater vehicles. Applications for this technology include Lost Asset and Survivor Location Systems (L-SALS) and Ship-in-Port Patrol and Protection (SP3). This research was a joint effort that included Nekton Research, LLC, Sandia National Laboratories, and Texas A&M University. Nekton Research developed the miniature autonomous underwater vehicles while Sandia and Texas A&M developed the 3-D plume tracing algorithms. This report describes the plume tracing algorithm and presents test results from successful underwater testing with pseudo-plume sources.

  17. Lagrangian computations of radiating fire plumes

    Science.gov (United States)

    Lakkis, Issam Adnan

    2000-09-01

    Modeling and simulation of fires are useful in determining their impact on nearby and distant objects, quantifying their environmental impact, improving fire suppression techniques, etc. Fires, essentially naturally aspirated combustion phenomena, are buoyancy driven diffusion flames in which the fuel supply rate is governed by the burn rate itself. It has been observed experimentally that the complex interaction between the flow, transport process and chemistry in a fire leads to large scale ``puffing'' an unsteady phenomenon manifested in the periodic ejection of bellowing smoke. The complexity of the phenomenon defies analytical treatment except at the very coarse grain level essentially using similarity principles. Numerical solutions based on ensemble averaging/closure and flow- combustion interaction models are encumbered by uncertainty and unproven hypotheses. A viable alternative is a numerical simulation of the unsteady governing equations with sufficient resolution to capture the important scales. In this work, contributions to a grid- free Lagrangian approach to simulate numerically fire plumes are suggested. The physical model incorporates unsteady buoyancy dynamics, transport of heat and mass by diffusion and convection, radiative transport of heat, and a single-step, infinite-rate chemical reaction with exothermic heat release. The numerical approach is based on the vortex method in which the unsteady conservation equations of vorticity, chemical species and energy are solved using a set of moving computational elements carrying time dependent quantities. A compatible approach is proposed to solve the radiative transport equations. Simulations of an axisymmetric plume are used to identify the dynamic mechanisms leading to ``puffing'', the processes which govern entrainment into the rising unsteady plume, burn rate, and overall observable quantities such as the flame height, radiation flux, etc. (Copies available exclusively from MIT Libraries, Rm. 14

  18. Cooling tower plume - model and experiment

    Directory of Open Access Journals (Sweden)

    Cizek Jan

    2017-01-01

    Full Text Available The paper discusses the description of the simple model of the, so-called, steam plume, which in many cases forms during the operation of the evaporative cooling systems of the power plants, or large technological units. The model is based on semi-empirical equations that describe the behaviour of a mixture of two gases in case of the free jet stream. In the conclusion of the paper, a simple experiment is presented through which the results of the designed model shall be validated in the subsequent period.

  19. Numerical Modelling of Jets and Plumes

    DEFF Research Database (Denmark)

    Larsen, Torben

    1993-01-01

    -dimensional integral method to the general 3-dimensional solution of the Navier-Stokes equations. Also the predictive capabilities of the models are discussed. The presentation takes the perspective of civil engineering and covers issues like sewage outfalls and cooling water discharges to the sea.......An overview on numerical models for prediction of the flow and mixing processes in turbulent jets and plumes is given. The overview is structured to follow an increasing complexity in the physical and numerical principles. The various types of models are briefly mentioned, from the one...

  20. Low-buoyancy thermochemical plumes resolve controversy of classical mantle plume concept

    National Research Council Canada - National Science Library

    Dannberg, Juliane; Sobolev, Stephan V

    2015-01-01

    .... We demonstrate that, despite their low buoyancy, large enough thermochemical plumes can rise through the whole mantle causing only negligible surface uplift. Their tails are bulky (>200 km radius) and remain in the upper mantle for 100 millions of years....

  1. SRS reactor stack plume marking tests

    Energy Technology Data Exchange (ETDEWEB)

    Petry, S.F.

    1992-03-01

    Tests performed in 105-K in 1987 and 1988 demonstrated that the stack plume can successfully be made visible (i.e., marked) by introducing smoke into the stack breech. The ultimate objective of these tests is to provide a means during an emergency evacuation so that an evacuee can readily identify the stack plume and evacuate in the opposite direction, thus minimizing the potential of severe radiation exposure. The EPA has also requested DOE to arrange for more tests to settle a technical question involving the correct calculation of stack downwash. New test canisters were received in 1988 designed to produce more smoke per unit time; however, these canisters have not been evaluated, because normal ventilation conditions have not been reestablished in K Area. Meanwhile, both the authorization and procedure to conduct the tests have expired. The tests can be performed during normal reactor operation. It is recommended that appropriate authorization and procedure approval be obtained to resume testing after K Area restart.

  2. Intercontinental transport of nitrogen oxide pollution plumes

    Directory of Open Access Journals (Sweden)

    M. Wenig

    2003-01-01

    Full Text Available We describe the first satellite observation of intercontinental transport of nitrogen oxides emitted by power plants, verified by simulations with a particle tracer model. The analysis of such episodes shows that anthropogenic NOx plumes may influence the atmospheric chemistry thousands of kilometers away from its origin, as well as the ocean they traverse due to nitrogen fertilization. This kind of monitoring became possible by applying an improved algorithm to extract the tropospheric fraction of NO2 from the spectral data coming from the GOME instrument. As an example we show the observation of NO2 in the time period 4--14 May, 1998, from the South African Plateau to Australia which was possible due to favourable weather conditions during that time period which availed the satellite measurement. This episode was also simulated with the Lagrangian particle dispersion model FLEXPART which uses NOx emissions taken from an inventory for industrial emissions in South Africa and is driven with analyses from the European Centre for Medium-Range Weather Forecasts. Additionally lightning emissions were taken into account by utilizing Lightning Imaging Sensor data. Lightning was found to contribute probably not more than 25% of the resulting concentrations. Both, the measured and simulated emission plume show matching patterns while traversing the Indian Ocean to Australia and show great resemblance to the aerosol and CO2 transport observed by Piketh et al. (2000.

  3. Short-Term Variability in Enceladus' Plume

    Science.gov (United States)

    Spitale, Joseph N.; Hurford, Terry; Rhoden, Alyssa R.

    2017-10-01

    The density of solids in Enceladus' south-polar plume at altitudes above about 50 km has been observed to vary by a factor of three between Enceladus' periapse and apoapse. This variability of the combined plume on the orbital time scale supports a relation between tidal stress and combined eruptive activity, and contains information about how the fractures fail in an averaged sense, but local variability is still not understood.Here we report on a sequence of three Cassini images showing a single collimated jet transitioning from dormant to active during a period of a few minutes. In the first image, the jet is not visible; in the subsequent images, it is seen increasing to heights of order 100 km. Prior estimates of particle velocities have been based on observing the vertical brightness profiles of steady-state eruptions. The non-steady-state jet observations discussed here provide a different way of measuring velocities, as the rate of change in density at each altitude can be estimated (using appropriate photometric assumptions). Moreover, the timing and location of the eruption contain information about the failure mechanism leading to an eruption at this particular time and place.Other jets may also be observed activating at this time, but the detections are less certain.

  4. Channelization of plumes beneath ice shelves

    KAUST Repository

    Dallaston, M. C.

    2015-11-11

    © 2015 Cambridge University Press. We study a simplified model of ice-ocean interaction beneath a floating ice shelf, and investigate the possibility for channels to form in the ice shelf base due to spatial variations in conditions at the grounding line. The model combines an extensional thin-film description of viscous ice flow in the shelf, with melting at its base driven by a turbulent ocean plume. Small transverse perturbations to the one-dimensional steady state are considered, driven either by ice thickness or subglacial discharge variations across the grounding line. Either forcing leads to the growth of channels downstream, with melting driven by locally enhanced ocean velocities, and thus heat transfer. Narrow channels are smoothed out due to turbulent mixing in the ocean plume, leading to a preferred wavelength for channel growth. In the absence of perturbations at the grounding line, linear stability analysis suggests that the one-dimensional state is stable to initial perturbations, chiefly due to the background ice advection.

  5. Laboratory Study of Dispersion of Buoyant Surface Plumes

    DEFF Research Database (Denmark)

    Petersen, Ole; Larsen, Torben

    1990-01-01

    A laboratory a study on surface dispersion of buoyant plumes in open channel turbulence in made, where the buoyancy is due to both salinity and heat. The measured parameters are the downstream derivative of a plume width and height, which are integral-characteristics of the distributions of density...

  6. Snowfall observations from natural-draft cooling tower plumes.

    Science.gov (United States)

    Kramer, M L; Seymour, D E; Smith, M E; Reeves, R W; Frankenberg, T T

    1976-09-24

    During the winter of 1975-1976, snowfall from the plumes of large natural-draft cooling towers of power plants has been observed. Snow accumulations up to 2.5 centimeters have been found on the ground at extended distances from the cooling towers, and visibility has been restricted to less than 1600 meters in the tower plume near ground level.

  7. Redox zones of a landfill leachate pollution plume (Vejen, Denmark)

    DEFF Research Database (Denmark)

    Lyngkilde, John; Christensen, Thomas Højlund

    1992-01-01

    , ferrogenic, nitrate-reducing and aerobic environments overa distance of 370 m. This redox zone sequence is consistent with thermodynamical principles and is closely matched by the leachate plume determined by the chloride plume distribution. The redox zone sequence is believed to be key in controlling...... the fate of reactive pollutants leached from the landfill....

  8. Imaging mantle plumes with instantaneous phase measurements of diffracted waves

    NARCIS (Netherlands)

    Rickers, F.; Fichtner, A.; Trampert, J.

    2012-01-01

    In a synthetic tomographic experiment, we succeeded to recover an idealized narrow mantle plume reaching deep into the lower mantle by using a misfit based on the instantaneous phase difference. A misfit based on simple cross-correlation traveltime shifts leaves the lower mantle part of the plume

  9. Morphology of the Zambezi River plume in the Sofala Bank ...

    African Journals Online (AJOL)

    The sampling plan called for 73 CTD stations that were interspersed with sampling of shrimp recruitment. ... had not been explored sufficiently in previous studies and it puts the Zambezi River plume in a short list of plumes across the globe that propagates in the direction opposite to the sense of a Kelvin or a shelf wave.

  10. Validation of smoke plume rise models using ground based lidar

    Science.gov (United States)

    Cyle E. Wold; Shawn Urbanski; Vladimir Kovalev; Alexander Petkov; Wei Min Hao

    2010-01-01

    Biomass fires can significantly degrade regional air quality. Plume rise height is one of the critical factors determining the impact of fire emissions on air quality. Plume rise models are used to prescribe the vertical distribution of fire emissions which are critical input for smoke dispersion and air quality models. The poor state of model evaluation is due in...

  11. Determining resolvability of mantle plumes with synthetic seismic modeling

    Science.gov (United States)

    Maguire, R.; Van Keken, P. E.; Ritsema, J.; Fichtner, A.; Goes, S. D. B.

    2014-12-01

    Hotspot volcanism in locations such as Hawaii and Iceland is commonly thought to be associated with plumes rising from the deep mantle. In theory these dynamic upwellings should be visible in seismic data due to their reduced seismic velocity and their effect on mantle transition zone thickness. Numerous studies have attempted to image plumes [1,2,3], but their deep mantle origin remains unclear. In addition, a debate continues as to whether lower mantle plumes are visible in the form of body wave travel time delays, or whether such delays will be erased due to wavefront healing. Here we combine geodynamic modeling of mantle plumes with synthetic seismic waveform modeling in order to quantitatively determine under what conditions mantle plumes should be seismically visible. We model compressible plumes with phase changes at 410 km and 670 km, and a viscosity reduction in the upper mantle. These plumes thin from greater than 600 km in diameter in the lower mantle, to 200 - 400 km in the upper mantle. Plume excess potential temperature is 375 K, which maps to seismic velocity reductions of 4 - 12 % in the upper mantle, and 2 - 4 % in the lower mantle. Previous work that was limited to an axisymmetric spherical geometry suggested that these plumes would not be visible in the lower mantle [4]. Here we extend this approach to full 3D spherical wave propagation modeling. Initial results using a simplified cylindrical plume conduit suggest that mantle plumes with a diameter of 1000 km or greater will retain a deep mantle seismic signature. References[1] Wolfe, Cecily J., et al. "Seismic structure of the Iceland mantle plume." Nature 385.6613 (1997): 245-247. [2] Montelli, Raffaella, et al. "Finite-frequency tomography reveals a variety of plumes in the mantle." Science 303.5656 (2004): 338-343. [3] Schmandt, Brandon, et al. "Hot mantle upwelling across the 660 beneath Yellowstone." Earth and Planetary Science Letters 331 (2012): 224-236. [4] Hwang, Yong Keun, et al

  12. Recycled crust and the secular cooling of mantle plumes

    Science.gov (United States)

    Gazel Dondi, E.; Herzberg, C. T.; Vidito, C. A.

    2012-12-01

    Current models suggest that the massive basaltic production responsible for the emplacement of Large Igneous Provinces (LIPS) during the Permian-Paleocene may represent the initial phases of some of the mantle plumes that feed the current ocean island basalts (OIB). In some cases this magmatism was so voluminous that it produced global environmental impacts. Recent petrological, geochemical and geophysical studies of some of these localities like Samoa, Hawaii, Galapagos provide evidence that melting is related to a true mantle plume that originates from a boundary layer beneath the upper mantle. Thus, plume-related magmas produced in OIB and LIPS and their connecting plume tracks provide evidence on mantle temperature, size and composition of heterogeneities, and deep geochemical cycles. Although a lot of work has been done on LIPS and OIB, no complete record of the evolution of a mantle plume is available to this point. Galapagos-related lavas provide a complete record of the evolution of a mantle plume since the plume's initial stages in the Cretaceous. In the case of the Galapagos, our work suggests a decrease from TP(max) of 1650 °C in the Cretaceous to 1500 °C in the present day. Our recent work on the Galapagos Islands and the preliminary work on older Galapagos-related terranes suggest that this secular cooling is related with increasing amounts of recycled crust in the plume. Detailed olivine chemistry shows that although peridotite is the dominant source lithology of the Galapagos Plume, a recycled pyroxenite component is also significant in both isotopically enriched and depleted domains of the archipelago. We suggest that this possibly represents two separate bodies of recycled crust within the Galapagos mantle plume.

  13. West Antarctic Mantle Plume Hypothesis and Basal Water Generation

    Science.gov (United States)

    Ivins, Erik; Seroussi, Helene; Wiens, Doug; Bondzio, Johannes

    2017-04-01

    The hypothesis of a deep mantle plume that manifests Pliocene and Quaternary volcanism and present-day seismicity in West Antarctica has been speculated for more than 30 years. Recent seismic images support the plume hypothesis as the cause of Marie Byrd Land (MBL) volcanism and geophysical structure [ Lloyd et al., 2015; Ramirez et al., 2016]. Mantle plumes can more that double the geothermal heat flux, qGHF, above nominal continental values at their axial peak position and raise qGHF in the surrounding plume head to 60 mW/m2 or higher. Unfortunately, there is a dearth of in-situ basal ice sheet data that sample the heat flux. Consequently, we examine a realistic distribution of heat flux associated with a late-Cenozoic mantle plume in West Antarctica and explore its impact on thermal and melt conditions near the ice sheet base. The solid Earth model assumes a parameterized deep mantle plume and head. The 3-D ice flow model includes an enthalpy framework and full-Stokes stress balance. Both the putative plume location and extent are uncertain. Therefore, we perform broadly scoped experiments to characterize plume related basal conditions. The experiments show that mantle plumes have an important local impact on the ice sheet, with basal melting rates reaching several centimeters per year directly above the hotspot. The downstream active lake system of Whillans Ice Stream suggests a rift-related source of anomalous mantle heat. However, the lack of lake and stream activity in MBL suggests a relatively weak plume: one that delivers less flux by 35% below the heat flux to the crustal surface at the site of the Yellowstone hotspot [e.g., DeNosaquo et al., 2009], with peak value no higher than about 145 mW/m2.

  14. Citizen CATE Experiment and Polar Plume Dynamics

    Science.gov (United States)

    Mitchell, Adriana; Penn, Matt; Baer, Robert; Bosh, Robert; Garrison, David; Gelderman, Richard; Hare, Honor; Isberner, Fred; Jensen, Logan; Kovac, Sarah; McKay, Myles; Pierce, Michael; Thompson, Patricia; Ursache, Andrei; Varsik, John R.; Walter, Donald; Watson, Zachary; Young, David; Citizen CATE Team

    2017-01-01

    During the summer of 2017, a total solar eclipse will pass over the continental United States, allowing millions of citizens the opportunity to experience a beautiful celestial event. The Citizen Continental-America Telescopic Eclipse (CATE) Experiment plans to harness the power of these many viewers by using volunteers from sites across the US to observe and record the total solar eclipse. The data acquired from each of these sites will be composed into a continuous 90-minute video, allowing the inner solar corona to be studied for an unprecedented length of time.Observations in Indonesia of the March 2016 total solar eclipse allowed initial testing and analysis of the inner corona polar plume dynamics. Using MATLAB, a routine was developed to identify the polar coronal threads and their angle relative to the radial direction to analyze the field line behavior at the boundary of the polar coronal holes.

  15. Identification of discontinuities in plasma plume evolution

    CERN Document Server

    Gojani, Ardian B; Obayashi, Shigeru

    2013-01-01

    The ejection of material during laser ablation gives rise to the development of discontinuities in the ambient gas. Several of these discontinuities are observed and characterized, including externally and internally propagating shock waves, contact surface, and the ionization front. Qualitative experimental observations and analysis of these discontinuities is presented. Results from shadowgraphy enabled determination of an irradiance threshold between two different ablation mechanisms, and determination of several stages of plasma plume evolution. Consideration of the refractive index as a dynamic sum of the contributions from gas and electrons led to separate identification of ionization front from the contact surface. Furthermore, ionization front was observed to lead the shock wave at the earlier stage of the ablation.

  16. Reaction front formation in contaminant plumes.

    Science.gov (United States)

    Cribbin, Laura B; Winstanley, Henry F; Mitchell, Sarah L; Fowler, Andrew C; Sander, Graham C

    2014-12-15

    The formation of successive fronts in contaminated groundwater plumes by subsoil bacterial action is a commonly accepted feature of their propagation, but it is not obviously clear from a mathematical standpoint quite how such fronts are formed or propagate. In this paper we show that these can be explained by combining classical reaction-diffusion theory involving just two reactants (oxidant and reductant), and a secondary reaction in which a reactant on one side of such a front is (re-)formed on the other side of the front via diffusion of its product across the front. We give approximate asymptotic solutions for the reactant profiles, and the propagation rate of the front. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Plume dynamics and shielding by the ablation plume during Er:YAG laser ablation.

    Science.gov (United States)

    Nahen, Kester; Vogel, Alfred

    2002-04-01

    Free-running Er:YAG lasers are used for precise tissue ablation in various clinical applications. The ablated material is ejected into the direction perpendicular to the tissue surface. We investigated the influence of shielding by the ablation plume on the energy deposition into an irradiated sample because it influences the ablation dynamics and the amount of material ablated. The investigations were performed using an Er:YAG laser with a pulse duration of 200 micros for the ablation of gelatin with different water contents, skin, and water. Laser flash photography combined with a dark field Schlieren technique was used to visualize gaseous and particulate ablation products, and to measure the distance traveled by the ablating laser beam through the ablation plume at various times after the beginning of the laser pulse. The temporal evolution of the transmission through the ablation plume was probed using a second free running Er:YAG laser beam directed parallel to the sample's surface. The ablation dynamics was found to consist of a vaporization phase followed by material ejection. The observation of droplet ejection during water ablation provided evidence that a phase explosion is the driving mechanism for material ejection. The laser light transmission was only slightly reduced by the vapor plume, but decreased by 25%-50% when the ejected material passed the probe beam. At radiant exposures approximately 10 times above the ablation threshold, the laser energy deposited into the sample amounted to only 61% of the incident energy for gelatin samples with 90% water content and to 86% for skin samples. For free-running Er:YAG laser pulses shielding must therefore be considered in modeling the ablation dynamics and determining the dosage for clinical applications.

  18. Plume propagation direction determination with SO2 cameras

    Science.gov (United States)

    Klein, Angelika; Lübcke, Peter; Bobrowski, Nicole; Kuhn, Jonas; Platt, Ulrich

    2017-03-01

    SO2 cameras are becoming an established tool for measuring sulfur dioxide (SO2) fluxes in volcanic plumes with good precision and high temporal resolution. The primary result of SO2 camera measurements are time series of two-dimensional SO2 column density distributions (i.e. SO2 column density images). However, it is frequently overlooked that, in order to determine the correct SO2 fluxes, not only the SO2 column density, but also the distance between the camera and the volcanic plume, has to be precisely known. This is because cameras only measure angular extents of objects while flux measurements require knowledge of the spatial plume extent. The distance to the plume may vary within the image array (i.e. the field of view of the SO2 camera) since the plume propagation direction (i.e. the wind direction) might not be parallel to the image plane of the SO2 camera. If the wind direction and thus the camera-plume distance are not well known, this error propagates into the determined SO2 fluxes and can cause errors exceeding 50 %. This is a source of error which is independent of the frequently quoted (approximate) compensation of apparently higher SO2 column densities and apparently lower plume propagation velocities at non-perpendicular plume observation angles.Here, we propose a new method to estimate the propagation direction of the volcanic plume directly from SO2 camera image time series by analysing apparent flux gradients along the image plane. From the plume propagation direction and the known location of the SO2 source (i.e. volcanic vent) and camera position, the camera-plume distance can be determined. Besides being able to determine the plume propagation direction and thus the wind direction in the plume region directly from SO2 camera images, we additionally found that it is possible to detect changes of the propagation direction at a time resolution of the order of minutes. In addition to theoretical studies we applied our method to SO2 flux

  19. The dominant effect of alumina on nearfield plume radiation

    Science.gov (United States)

    Laredo, David; Netzer, David W.

    1993-11-01

    Solid propellant rocket motors can achieve high specific impulse with metal fuel additives such as aluminum. Combustion of aluminum produces condensed alumina particles. Besides causing performance losses in the nozzle, the condensed Al2O3 particles are the major source of primary smoke in the exhaust plume. The particulate matter can also have major effects upon the plume i.r. signature. High number densities of particles can block gas-phase radiation from the plume. They can also be the source of radiation, especially the larger particles which exit the nozzle not in thermal equilibrium with the gas. In the past, the expected effects of particle size on the plume i.r. signature have been determined almost exclusively from predictions made with flow and radiation codes. The aim of the present work was to investigate the role of the Al/Al2O3 particles from a highly loaded solid propellant (up to 16% in weight) on the plume radiation of a small rocket motor (5 cm in diameter). The spatial variation of particle size distribution was simultaneously measured with the overall radiation of a portion of the plume in the i.r. band (3.5-5.0 microns). In micro-motors, operating with highly aluminized solid propellant, the condensed particles in the near exhaust plume were the major source of radiation in the 3.5-5 micron wavelength band. Motors with longer residence time and operating at medium chamber pressures produced more particles in the micron sized range. The role of after burning was predominately confined to reheating of the alumina particles to a higher temperature, at which the condensed Al2O3 radiated more than gaseous species. Even with 30% Al2O3 in the plume, the plume of small motors can be considered as approximately conical in shape, with volume distributed radiating sources. Motor conditions producing larger particles in the plume core were thus found to increase plume radiation from that region. The overall apparent emissivity of the plume was between 0

  20. Detecting Volcanic Ash Plumes with GNSS Signals

    Science.gov (United States)

    Rainville, N.; Larson, K. M.; Palo, S. E.; Mattia, M.; Rossi, M.; Coltelli, M.; Roesler, C.; Fee, D.

    2016-12-01

    Global Navigation Satellite Systems (GNSS) receivers are commonly placed near volcanic sites to measure ground deformation. In addition to the carrier phase data used to measure ground position, these receivers also record Signal to Noise ratio (SNR) data. Larson (2013) showed that attenuations in SNR data strongly correlate with ash emissions at a series of eruptions of Redoubt Volcano. This finding has been confirmed at eruptions for Tongariro, Mt Etna, Mt Shindake, and Sakurajima. In each of these detections, very expensive geodetic quality GNSS receivers were used. If low-cost GNSS instruments could be used instead, a networked array could be deployed and optimized for plume detection and tomography. The outputs of this sensor array could then be used by both local volcanic observatories and Volcano Ash Advisory Centers. Here we will describe progress in developing such an array. The sensors we are working with are intended for navigation use, and thus lack the supporting power and communications equipment necessary for a networked system. Reliably providing those features is major challenge for the overall sensor design. We have built prototypes of our Volcano Ash Plume Receiver (VAPR), with solar panels, lithium-ion batteries and onboard data storage for preliminary testing. We will present results of our field tests of both receivers and antennas. A second critical need for our array is a reliable detection algorithm. We have tested our algorithm on data from recent eruptions and have incorporated the noise characteristics of the low-cost GNSS receiver. We have also developed a simulation capability so that the receivers can be deployed to optimize vent crossing GNSS signals.

  1. Dust Plume off the Coast of Egypt

    Science.gov (United States)

    2007-01-01

    Dwarfing the Nile, a river of dust flowed out of the deserts of northern Egypt on May 19, 2007. As the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite passed overhead at 12:05 p.m. local time in Cairo, the sensor captured this image of the dust spreading northward over the Mediterranean Sea from the sandy deserts that span the country. At the margins of the plume, ribbons and ripples of dust are translucent, allowing a glimpse of the desert and water beneath, but in the center, the cloud is opaque, revealing nothing of the surface below. The part of north-central Egypt hidden by the dust plume is the Qattara Depression, the country's lowest point. Dipping down to 133 meters below sea level (436 feet), the depression is home to sandy deserts and dry lake beds that occasionally flood. The sand and fine, lake bed sediments are easily lofted into the air by strong winds that scour the area in late winter and early spring. In the eastern (right-hand) part of the image, the Nile River is lined by narrow ribbons of dull green vegetation. The fan-shaped delta is dotted with tan-colored spots, marking the location of cities and towns. The Nile Valley and Delta make up only a small fraction of the country's total land area, yet they support almost the entire population. The large image provided above has a spatial resolution (level of detail) of 250 meters per pixel. The MODIS Rapid Response Team provides this image in additional resolutions. The Earth Observatory also provides a 250-meter-resolution KMZ file of this image for use with Google Earth.

  2. Learning to rapidly re-contact the lost plume in chemical plume tracing.

    Science.gov (United States)

    Cao, Meng-Li; Meng, Qing-Hao; Wang, Jia-Ying; Luo, Bing; Jing, Ya-Qi; Ma, Shu-Gen

    2015-03-27

    Maintaining contact between the robot and plume is significant in chemical plume tracing (CPT). In the time immediately following the loss of chemical detection during the process of CPT, Track-Out activities bias the robot heading relative to the upwind direction, expecting to rapidly re-contact the plume. To determine the bias angle used in the Track-Out activity, we propose an online instance-based reinforcement learning method, namely virtual trail following (VTF). In VTF, action-value is generalized from recently stored instances of successful Track-Out activities. We also propose a collaborative VTF (cVTF) method, in which multiple robots store their own instances, and learn from the stored instances, in the same database. The proposed VTF and cVTF methods are compared with biased upwind surge (BUS) method, in which all Track-Out activities utilize an offline optimized universal bias angle, in an indoor environment with three different airflow fields. With respect to our experimental conditions, VTF and cVTF show stronger adaptability to different airflow environments than BUS, and furthermore, cVTF yields higher success rates and time-efficiencies than VTF.

  3. Learning to Rapidly Re-Contact the Lost Plume in Chemical Plume Tracing

    Directory of Open Access Journals (Sweden)

    Meng-Li Cao

    2015-03-01

    Full Text Available Maintaining contact between the robot and plume is significant in chemical plume tracing (CPT. In the time immediately following the loss of chemical detection during the process of CPT, Track-Out activities bias the robot heading relative to the upwind direction, expecting to rapidly re-contact the plume. To determine the bias angle used in the Track-Out activity, we propose an online instance-based reinforcement learning method, namely virtual trail following (VTF. In VTF, action-value is generalized from recently stored instances of successful Track-Out activities. We also propose a collaborative VTF (cVTF method, in which multiple robots store their own instances, and learn from the stored instances, in the same database. The proposed VTF and cVTF methods are compared with biased upwind surge (BUS method, in which all Track-Out activities utilize an offline optimized universal bias angle, in an indoor environment with three different airflow fields. With respect to our experimental conditions, VTF and cVTF show stronger adaptability to different airflow environments than BUS, and furthermore, cVTF yields higher success rates and time-efficiencies than VTF.

  4. Learning to Rapidly Re-Contact the Lost Plume in Chemical Plume Tracing

    Science.gov (United States)

    Cao, Meng-Li; Meng, Qing-Hao; Wang, Jia-Ying; Luo, Bing; Jing, Ya-Qi; Ma, Shu-Gen

    2015-01-01

    Maintaining contact between the robot and plume is significant in chemical plume tracing (CPT). In the time immediately following the loss of chemical detection during the process of CPT, Track-Out activities bias the robot heading relative to the upwind direction, expecting to rapidly re-contact the plume. To determine the bias angle used in the Track-Out activity, we propose an online instance-based reinforcement learning method, namely virtual trail following (VTF). In VTF, action-value is generalized from recently stored instances of successful Track-Out activities. We also propose a collaborative VTF (cVTF) method, in which multiple robots store their own instances, and learn from the stored instances, in the same database. The proposed VTF and cVTF methods are compared with biased upwind surge (BUS) method, in which all Track-Out activities utilize an offline optimized universal bias angle, in an indoor environment with three different airflow fields. With respect to our experimental conditions, VTF and cVTF show stronger adaptability to different airflow environments than BUS, and furthermore, cVTF yields higher success rates and time-efficiencies than VTF. PMID:25825974

  5. NW Iberia Shelf Dynamics. Study of the Douro River Plume.

    Directory of Open Access Journals (Sweden)

    Isabel Iglesias

    2014-06-01

    Full Text Available River plumes are one of the most important mechanisms that transport the terrestrial materials to the coast and the ocean. Some examples of those materials are pollutants, essential nutrients, which enhance the phytoplankton productivity or sediments, which settle on the seabed producing modifications on the bathymetry affecting the navigation channels. The mixing between the riverine and the oceanic waters can induce instabilities, which might generate bulges, filaments, and buoyant currents over the continental shelf. Offshore, the buoyant riverine water could form a front with the oceanic waters often related with the occurrence of current-jets, eddies and strong mixing. The study and modelling of the river plumes is a key factor for the complete understanding of sediment transport mechanisms and patterns, and of coastal physics and dynamic processes. On this study the Douro River plume will be simulated. The Douro River is located on the north-west Iberian coast and its daily averaged freshwater discharge can range values from 0 to 13000 m3/s. This variability impacts the formation of the river plumes and its dispersion along the continental shelf. This study builds on the long-term objective of generate a Douro River plume forecasting system as part of the RAIA and RAIA.co projects. Satellite imagery was analyzed showing that the river Douro is one of the main sources of suspended particles, dissolved material and chlorophyll in the NW Iberian Shelf. The Regional Oceanic Modeling System (ROMS model was selected to reproduce scenarios of plume generation, retention and dispersion. Whit this model, three types of simulations were performed: (i schematic winds simulations with prescribed river flow, wind speed and direction; (ii multi-year climatological simulation, with river flow and temperature change for each month; (iii extreme case simulation, based on the Entre-os-Rios accident situation. The schematic wind case-studies suggest that the

  6. Analysis of plasmaspheric plumes: CLUSTER and IMAGE observations

    Directory of Open Access Journals (Sweden)

    F. Darrouzet

    2006-07-01

    Full Text Available Plasmaspheric plumes have been routinely observed by CLUSTER and IMAGE. The CLUSTER mission provides high time resolution four-point measurements of the plasmasphere near perigee. Total electron density profiles have been derived from the electron plasma frequency identified by the WHISPER sounder supplemented, in-between soundings, by relative variations of the spacecraft potential measured by the electric field instrument EFW; ion velocity is also measured onboard these satellites. The EUV imager onboard the IMAGE spacecraft provides global images of the plasmasphere with a spatial resolution of 0.1 RE every 10 min; such images acquired near apogee from high above the pole show the geometry of plasmaspheric plumes, their evolution and motion. We present coordinated observations of three plume events and compare CLUSTER in-situ data with global images of the plasmasphere obtained by IMAGE. In particular, we study the geometry and the orientation of plasmaspheric plumes by using four-point analysis methods. We compare several aspects of plume motion as determined by different methods: (i inner and outer plume boundary velocity calculated from time delays of this boundary as observed by the wave experiment WHISPER on the four spacecraft, (ii drift velocity measured by the electron drift instrument EDI onboard CLUSTER and (iii global velocity determined from successive EUV images. These different techniques consistently indicate that plasmaspheric plumes rotate around the Earth, with their foot fully co-rotating, but with their tip rotating slower and moving farther out.

  7. Experiments on Plume Spreading by Engineered Injection and Extraction

    Science.gov (United States)

    Mays, D. C.; Jones, M.; Tigera, R. G.; Neupauer, R.

    2014-12-01

    The notion that groundwater remediation is transport-limited emphasizes the coupling between physical (i.e., hydrodynamic), geochemical, and microbiological processes in the subsurface. Here we leverage this coupling to promote groundwater remediation using the approach of engineered injection and extraction. In this approach, inspired by the literature on chaotic advection, uncontaminated groundwater is injected and extracted through a manifold of wells surrounding the contaminated plume. The potential of this approach lies in its ability to actively manipulate the velocity field near the contaminated plume, generating plume spreading above and beyond that resulting from aquifer heterogeneity. Plume spreading, in turn, promotes mixing and reaction by chemical and biological processes. Simulations have predicted that engineered injection and extraction generates (1) chaotic advection whose characteristics depend on aquifer heterogeneity, and (2) faster rates and increased extent of groundwater remediation. This presentation focuses on a complimentary effort to experimentally demonstrate these predictions experimentally. In preparation for future work using refractive index matched (RIM) porous media, the experiments reported here use a Hele-Shaw apparatus containing silicone oil. Engineered injection and extraction is used to manipulate the geometry of an initially circular plume of black pigment, and photographs record the plume geometry after each step of injection of extraction. Image analysis, using complimentary Eulerian and Lagrangian approaches, reveals the thickness and variability of the dispersion zone surrounding the deformed plume of black pigment. The size, shape, and evolution of this dispersion zone provides insight into the interplay between engineered injection and extraction, which generates plume structure, and dispersion (here Taylor dispersion), which destroys plume structure. These experiments lay the groundwork for application of engineered

  8. Constraints on the detection of cryovolcanic plumes on Europa

    Science.gov (United States)

    Quick, Lynnae C.; Barnouin, Olivier S.; Prockter, Louise M.; Patterson, G. Wesley

    2013-09-01

    Surface venting is a common occurrence on several outer solar system satellites. Spacecraft have observed plumes erupting from the geologically young surfaces of Io, Triton and Enceladus. Europa also has a relatively young surface and previous studies have suggested that cryovolcanic eruptions may be responsible for the production of low-albedo deposits surrounding lenticulae and along triple band margins and lineae. Here, we have used the projected thicknesses of these deposits as constraints to determine the lifetimes of detectable cryovolcanic plumes that may have emplaced them. In an effort to explore the feasibility of detection of the particle component of plumes by spacecraft cameras operating at visible wavelengths, we present a conservative model to estimate plume characteristics such as height, eruption velocity, and optical depth under a variety of conditions. We find that cryovolcanic plumes on Europa are likely to be fairly small in stature with heights between 2.5 and 26 km, and eruption velocities between 81 and 261 m/s, respectively. Under these conditions and assuming that plumes are products of steady eruptions with particle radii of 0.5 μm, our model suggests that easily detectable plumes will have optical depths, τ, greater than or equal to 0.04, and that their lifetimes may be no more than 300,000 years. Plume detection may be possible if high phase angle limb observations and/or stereo imaging of the surface are undertaken in areas where eruptive activity is likely to occur. Cameras with imaging resolutions greater than 50 m/pixel should be used to make all observations. Future missions could employ the results of our model in searches for plume activity at Europa.

  9. Airborne Gamma-ray Measurements in the Chernobyl Plume

    DEFF Research Database (Denmark)

    Grasty, R. L.; Hovgaard, Jens; Multala, J.

    1997-01-01

    On 29 April 1986, the Geological Survey of Finland (GSF) survey aircraft with a gamma ray spectrometer flew through a radioactive plume from the Chernobyl nuclear accident. The aircraft became contaminated and the gamma spectrometer measured radioactivity in the plume as well as radioactivity...... on the aircraft. By using simple assumptions on the build-up of contamination it has been possible to separate the signals from contamination and from plume. The analysis further showed that even a detector/spectrometer with low energy resolution is able to identify a contamination with iodine....

  10. Single thermal plume in locally heated vertical soap films.

    Science.gov (United States)

    Adami, N; Dorbolo, S; Caps, H

    2011-10-01

    A vertical soap film is maintained by injection of a soap solution from the top. The film is then locally heated. Thermal plumes may be observed to rise in the film, depending on the magnitude of the heating and injected flows. The nearly two-dimensional nature of the system allows to visualize the motion of the plumes using an infrared camera. A model is proposed to describe the growth, emergence, and stationarity of the plumes in the film by taking into account both magnitudes of the heating ΔT and injected flow Q.

  11. Capability of MODIS radiance to analyze Iberian turbid plumes

    Science.gov (United States)

    Fernandez-Novoa, Diego; deCastro, Maite; Des, Marisela; Costoya, Xurxo; Mendes, Renato; Gomez-Gesteira, Moncho

    2017-04-01

    River plumes are formed near river mouths by freshwater and riverine materials. Therefore, the area influenced by freshwater (salinity plume) is usually negatively correlated with the area occupied by suspension and dissolved material (turbid plume). Suspended material results in a strong signal detected by satellite sensors whereas ocean clear waters have negligible contributions. Thus, remote sensing data, such as radiance obtained from Moderate Resolution Imaging Spectroradiometer (MODIS), are a very useful tool to analyze turbid plumes due to the high spatial and time resolution provided. Here, MODIS capability for characterizing similarities and differences among the most important Iberian plumes was assessed under the influence of their main forcing. Daily radiance data from MODIS-Aqua and MODIS-Terra satellite sensors were processed obtaining a resolution of 500 m. Two approaches are usually used for atmospheric correction treatments: Near-Infrared (NIR) bands and a combined algorithm using NIR and Short Wave Infrared (SWIR) bands. In the particular case of Iberian Peninsula plumes both methods offered similar results, although NIR bands present a lower associated error. MODIS allows working with several bands of normalized water-leaving radiances (nLw). Focusing in the resolution provided, nLw555 and 645 were the most appropriate because both provide the best coverage and correlation with river discharge. The nLw645 band was chosen because has a lower water penetration avoiding overestimations of turbidity caused by shallow seafloor areas and/or upwelling blooms. Daily data from both satellites were merged to enhance the robustness and precision of the study by increasing the number of available pixels. Results indicate that differences between radiance data from both satellites are negligible for Iberian plumes, justifying the merging. By last, each turbid limit, to delimit the respective plume from adjacent seawater, was obtained using two alternative

  12. CONSEQUENCES OF NON-LINEAR DENSITY EFFECTS ON BUOYANCY AND PLUME BEHAVIOR

    Science.gov (United States)

    Aquatic plumes, as turbulent streams, grow by entraining ambient water. Buoyant plumes rise and dense ones sink, but, non-linear kinetic effects can reverse the buoyant force in mid-phenomenon. The class of nascent-density plumes begin as buoyant, upwardly accelerating plumes tha...

  13. Small particles in plumes of Mount St. Helens

    Science.gov (United States)

    Rose, W. I.; Chuan, R. L.; Woods, D. C.

    1982-01-01

    Particles in the size range 0.1-25 microns were sampled by aircraft carrying a quartz crystal microcascade in the Mount St. Helens plume on three dates in August and September 1980. Two of the sampling dates represented 'typical' emissions of the volcano between plinian eruptions. One sampling flight was made 1-4 hours before the small plinian eruption of August 7, 1980 when the plume had become discontinuous and visibly darker. The plume sampled on August 7, before the eruption, contained mainly approximately 2-micron diameter silicic glass particles, fragments of the Mount St. Helens magma. The typical plumes sampled on September 22 and August 6 had much smaller concentrations of particles, trimodal size distributions with peaks at 10, 0.4, and 0.1 microns. The particles were largely nonsilicate and apparently represented Cu-Zn oxide (10 micron peak), Al sulfate, chloride, and oxide, and sulfuric acid (smallest size peak).

  14. Volcanic ash plume identification using polarization lidar: Augustine eruption, Alaska

    Science.gov (United States)

    Sassen, Kenneth; Zhu, Jiang; Webley, Peter W.; Dean, K.; Cobb, Patrick

    2007-01-01

    During mid January to early February 2006, a series of explosive eruptions occurred at the Augustine volcanic island off the southern coast of Alaska. By early February a plume of volcanic ash was transported northward into the interior of Alaska. Satellite imagery and Puff volcanic ash transport model predictions confirm that the aerosol plume passed over a polarization lidar (0.694 mm wavelength) site at the Arctic Facility for Atmospheric Remote Sensing at the University of Alaska Fairbanks. For the first time, lidar linear depolarization ratios of 0.10 – 0.15 were measured in a fresh tropospheric volcanic plume, demonstrating that the nonspherical glass and mineral particles typical of volcanic eruptions generate strong laser depolarization. Thus, polarization lidars can identify the volcanic ash plumes that pose a threat to jet air traffic from the ground, aircraft, or potentially from Earth orbit.

  15. Near-Shore Hydrodynamic Conditions and Chemical Plume Tracking

    National Research Council Canada - National Science Library

    Fong, Derek

    2004-01-01

    .... Analyzing a dye concentration data set collected by a state of the art autonomous underwater vehicle and fixed hydrodynamic measurements, we quantify the meandering and lateral dispersion of a plume...

  16. Hydrocarbon Rocket Engine Plume Imaging with Laser Induced Incandescence Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA/ Marshall Space Flight Center (MSFC) needs sensors that can be operated on rocket engine plume environments to improve NASA/SSC rocket engine performance. In...

  17. A Thermal Plume Model for the Martian Convective Boundary Layer

    CERN Document Server

    Colaïtis, Arnaud; Hourdin, Frédéric; Rio, Catherine; Forget, François; Millour, Ehouarn

    2013-01-01

    The Martian Planetary Boundary Layer [PBL] is a crucial component of the Martian climate system. Global Climate Models [GCMs] and Mesoscale Models [MMs] lack the resolution to predict PBL mixing which is therefore parameterized. Here we propose to adapt the "thermal plume" model, recently developed for Earth climate modeling, to Martian GCMs, MMs, and single-column models. The aim of this physically-based parameterization is to represent the effect of organized turbulent structures (updrafts and downdrafts) on the daytime PBL transport, as it is resolved in Large-Eddy Simulations [LESs]. We find that the terrestrial thermal plume model needs to be modified to satisfyingly account for deep turbulent plumes found in the Martian convective PBL. Our Martian thermal plume model qualitatively and quantitatively reproduces the thermal structure of the daytime PBL on Mars: superadiabatic near-surface layer, mixing layer, and overshoot region at PBL top. This model is coupled to surface layer parameterizations taking ...

  18. AASERT: Hydrodynamic Interaction Between Olfactory Antennae and Odor Plumes

    National Research Council Canada - National Science Library

    Koehl, M

    2002-01-01

    ... other. In the turbulent water flow typical of shallow coastal habitats, odor plumes are characterized by complex swirls of narrow filaments of high concentration near the odor source, but wider filaments...

  19. Saturated Zone Plumes in Volcanic Rock: Implications for Yucca Mountain

    Energy Technology Data Exchange (ETDEWEB)

    S. Kelkar; R. Roback; B. Robinson; G. Srinivasan; C. Jones; P. Reimus

    2006-02-14

    This paper presents a literature survey of the occurrences of radionuclide plumes in saturated, fractured rocks. Three sites, Idaho National laboratory, Hanford, and Oak Ridge are discussed in detail. Results of a modeling study are also presented showing that the length to width ratio of a plume starting within the repository footprint at the Yucca Mountain Project site, decreases from about 20:1 for the base case to about 4:1 for a higher value of transverse dispersivity, indicating enhanced lateral spreading of the plume. Due to the definition of regulatory requirements, this lateral spreading does not directly impact breakthrough curves at the 18 km compliance boundary, however it increases the potential that a plume will encounter reducing conditions, thus significantly retarding the transport of sorbing radionuclides.

  20. Turbulent Boyant Jets and Plumes in Flowing Ambient Environments

    DEFF Research Database (Denmark)

    Chen, Hai-Bo

    Turbulent buoyant jets and plumes in flowing ambient environments have been studied theoretically and experimentally. The mechanics of turbulent buoyant jets and plumes in flowing ambients have been discussed. Dimensional analysis was employed to investigate the mean behaviour of the turbulent....... Comprehensive laboratory experiments were conducted to study the mean behaviour of turbulent buoyant jets and plumes in a flowing ambient by using both fresh and salt receiving waters. The experimental data on the jet trajectories and dilutions, for a horizontal jet in a coflowing ambient and for a vertical jet......, the available field observated data on the initial dilutions for a horizontal jet issuing into a perpendicular crossflowing ambient have been presented and discussed. Mathematical modelling of the turbulent buoyant jets and plumes has been carried out by using both an integral model and a turbulence model...

  1. Airborne Remote Sensing of the Plata Plume Using STARRS

    National Research Council Canada - National Science Library

    Perez, Tabare; Wesson, Joel C; Burrage, Derek

    2006-01-01

    ...s. An international project, La Plata, was undertaken within the South American Climate Change Consortium framework to assess the behavior of the La Plata and Patos Lagoon plumes and their effects...

  2. Dynamics of femtosecond laser produced tungsten nanoparticle plumes

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, S. S.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Farid, N. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); School of Physics and Optical Engineering, Dalian University of Technology, Dalian 116024 (China); Kozhevin, V. M. [Ioffe Physics Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation)

    2013-11-28

    We investigated the expansion features of femtosecond laser generated tungsten nanoparticle plumes in vacuum. Fast gated images showed distinct two components expansion features, viz., plasma and nanoparticle plumes, separated by time of appearance. The persistence of plasma and nanoparticle plumes are ∼500 ns and ∼100 μs, respectively, and propagating with velocities differed by 25 times. The estimated temperature of the nanoparticles showed a decreasing trend with increasing time and space. Compared to low-Z materials (e.g., Si), ultrafast laser ablation of high-Z materials like W provides significantly higher nanoparticle yield. A comparison between the nanoparticle plumes generated by W and Si is also discussed along with other metals.

  3. Dynamics of femtosecond laser produced tungsten nanoparticle plumes

    Science.gov (United States)

    Harilal, S. S.; Farid, N.; Hassanein, A.; Kozhevin, V. M.

    2013-11-01

    We investigated the expansion features of femtosecond laser generated tungsten nanoparticle plumes in vacuum. Fast gated images showed distinct two components expansion features, viz., plasma and nanoparticle plumes, separated by time of appearance. The persistence of plasma and nanoparticle plumes are ˜500 ns and ˜100 μs, respectively, and propagating with velocities differed by 25 times. The estimated temperature of the nanoparticles showed a decreasing trend with increasing time and space. Compared to low-Z materials (e.g., Si), ultrafast laser ablation of high-Z materials like W provides significantly higher nanoparticle yield. A comparison between the nanoparticle plumes generated by W and Si is also discussed along with other metals.

  4. Directions of seismic anisotropy in laboratory models of mantle plumes

    Science.gov (United States)

    Druken, K. A.; Kincaid, C.; Griffiths, R. W.

    2013-07-01

    recent expansion in global seismic anisotropy data provides important new insights about the style of mantle convection. Interpretations of these geophysical measurements rely on complex relationships between mineral physics, seismology, and mantle dynamics. We report on 3-D laboratory experiments using finite strain markers evolving in time-dependent, viscous flow fields to quantify the range in expected anisotropy patterns within buoyant plumes surfacing in a variety of tectonic settings. A surprising result is that laboratory proxies for the olivine fast axis overwhelmingly align tangential to radial outflow in plumes well before reaching the surface. These remarkably robust, and ancient, anisotropy patterns evolve differently in stagnant, translational, and divergent plate tectonic settings and are essentially orthogonal to patterns typically referenced when prospecting for plume signals in seismic data. Results suggest a fundamental change in the mineral physics-seismology-circulation relationship used in accepting or rejecting a plume model.

  5. Analysis of bubble plume spacing produced by regular breaking waves

    Science.gov (United States)

    Phaksopa, J.; Haller, M. C.

    2012-12-01

    The breaking wave process in the ocean is a significant mechanism for energy dissipation, splash, and entrainment of air. The relationship between breaking waves and bubble plume characteristics is still a mystery because of the complexity of the breaking wave mechanism. This study takes a unique approach to quantitatively analyze bubble plumes produced by regular breaking waves. Various previous studies have investigated the formation and the characteristics of bubble plumes using either field observations, laboratory experiments, or numerical modeling However, in most observational work the plume characteristics have been studied from the underneath the water surface. In addition, though numerical simulations are able to include much of the important physics, the computational costs are high and bubble plume events are only simulated for short times. Hence, bubble plume evolution and generation throughout the surf zone is not yet computationally feasible. In the present work we take a unique approach to analyzing bubble plumes. These data may be of use for model/data comparisons as numerical simulations become more tractable. The remotely sensed video data from freshwater breaking waves in the OSU Large Wave Flume (Catalan and Haller, 2008) are analyzed. The data set contains six different regular wave conditions and the video intensity data are used to estimate the spacing of plume events (wavenumber spectrum), to calculate the spectral width (i.e. the range of plume spacing), and to relate these with the wave conditions. The video intensity data capture the evolution of the wave passage over a fixed bed arranged in a bar-trough morphology. Bright regions represent the moving path or trajectory coincident with bubble plume of each wave. It also shows the bubble foam were generated and released from wave crest shown in the form of bubble tails with almost regular spacing for each wave. The bubble tails show that most bubbles did not move along with wave. For the

  6. Particle resuspension in the Columbia River plume near field

    Science.gov (United States)

    Spahn, Emily Y.; Horner-Devine, Alexander R.; Nash, Jonathan D.; Jay, David A.; Kilcher, Levi

    2009-02-01

    Measurements of suspended sediment concentration, velocity, salinity, and turbulent microscale shear in the near-field region of the Columbia River plume are used to investigate the mechanisms of sediment resuspension and entrainment into the plume. An east-west transect was occupied during spring and neap tide periods in August 2005 and May 2006, corresponding to low and high river discharge conditions, respectively. During the high-discharge period the plume is decoupled from the bottom, and fine sediment resuspended from the bottom does not leave the benthic boundary layer. The primary modes of sediment transport associated with the plume are advection of sediment from the estuary and removal of sediment from the plume by gravitational settling and turbulent mixing. In contrast, the plume is much less stratified during low-discharge conditions, and large resuspension events are observed that entrained sediment through the water column and into the plume. Our measurements indicate that two factors control the magnitude and timing of sediment resuspension and entrainment: the supply of fine sediment on the seabed and the relative influence of tidal turbulence compared with buoyancy input from the river. The latter is quantified in terms of the estuary Richardson number RiE. The magnitude of vertical turbulent sediment flux is correlated with RiE during the low-flow period when there is a sufficient supply of bottom sediment in the near-field region. Such sediment resuspension may be an important mechanism for the delivery of bioavailable micronutrients to the plume during the summer.

  7. MODELING AN IRRITANT GAS PLUME FOR EPIDEMIOLOGIC STUDY

    OpenAIRE

    Jani, Dev D.; Reed, David; Feigley, Charles E.; Svendsen, Erik R.

    2015-01-01

    Plume dispersion modeling systems are often used in assessing human exposures to chemical hazards for epidemiologic study. We modeled the 2005 Graniteville, South Carolina, 54,915 kg railcar chlorine release using both the Areal Locations of Hazardous Atmospheres (ALOHA) and Hazard Prediction and Assessment Capability (HPAC) plume modeling systems. We estimated the release rate by an engineering analysis combining semi-quantitative observations and fundamental physical principles. The use of ...

  8. Chemical Plume Detection with an Iterative Background Estimation Technique

    Science.gov (United States)

    2016-05-17

    is inspired by spatial point process analysis techniques , and involves an iterative filtering process. The detection of chemical vapors is...Chemical Plume Detection with an Iterative Background Estimation Technique Eric Truslowa, Steven Golowicha, Dimitris Manolakisa aMIT-Lincoln...Laboratory, 244 Wood Street, Lexington, MA 02420, U.S.A. ABSTRACT The detection of chemical vapor plumes using passive hyperspectral sensors operating in the

  9. Numerical simulations of rotating bubble plumes in stratified environments

    Science.gov (United States)

    Fabregat Tomà s, Alexandre; Poje, Andrew C.; Ã-zgökmen, Tamay M.; Dewar, William K.

    2017-08-01

    The effects of system rotation on the turbulent dynamics of bubble plumes evolving in stratified environments are numerically investigated by considering variations in both the system rotation rate and the gas-phase slip velocity. The turbulent dispersion of a passive scalar injected at the source of a buoyant plume is strongly altered by the rotation of the system and the nature of the buoyancy at the source. When the plume is driven by the density defect associated with the presence of slipping gas bubbles, the location of the main lateral intrusion decreases with respect to the single-phase case with identical inlet volume, momentum, and buoyancy fluxes. Enhanced downdrafts of carrier phase fluid result in increased turbulent mixing and short-circuiting of detraining plume water that elevate near-field effluent concentrations. Similarly, rotation fundamentally alters dynamic balances within the plume leading to the encroachment of the trapping height on the source and an increase in turbulent dispersion in the near field. System rotation, even at modest Rossby numbers, produces a sustained, robust, anticyclonic precession of the plume core. The effects of rotation and the presence of bubbles are cumulative. The vertical encroachment of the primary intrusion and the overall dispersion of effluent are greatest at smallest Rossby numbers and largest slip velocities. The main characteristic feature in rotating single-phase plumes, namely the robust anticyclonic precession, persists in bubble plumes. Analysis of the momentum budgets reveal that the mechanism responsible for the organized precession, i.e., the establishment of an unstable vertical hydrostatic equilibrium related to radial cyclostrophic balance, does not differ from the single-phase case.

  10. Wireless Sensor Network Based Subsurface Contaminant Plume Monitoring

    Science.gov (United States)

    2012-04-16

    conventional WSN . VSN enabled closed loop system consumes more energy than the VSN only system, because of the commands that are send to the nodes. Energy ...predict future plume behavior. This proof-of-concept research aimed at demonstrating the use of an intelligent Wireless Sensor Network ( WSN ) to...Network ( WSN ) to monitor contaminant plume movement in naturally heterogeneous subsurface formations to advance the sensor networking based monitoring

  11. Site characterization and petroleum hydrocarbon plume mapping

    Energy Technology Data Exchange (ETDEWEB)

    Ravishankar, K. [Harding Lawson Associates, Houston, TX (United States)

    1996-12-31

    This paper presents a case study of site characterization and hydrocarbon contamination plume mapping/delineation in a gas processing plant in southern Mexico. The paper describes innovative and cost-effective use of passive (non-intrusive) and active (intrusive) techniques, including the use of compound-specific analytical methods for site characterization. The techniques used, on a demonstrative basis, include geophysical, geochemical, and borehole drilling. Geochemical techniques used to delineate the horizontal extent of hydrocarbon contamination at the site include soil gas surveys. The borehole drilling technique used to assess the vertical extent of contamination and confirm geophysical and geochemical data combines conventional hollow-stem auguring with direct push-probe using Geoprobe. Compound-specific analytical methods, such as hydrocarbon fingerprinting and a modified method for gasoline range organics, demonstrate the inherent merit and need for such analyses to properly characterize a site, while revealing the limitations of noncompound-specific total petroleum hydrocarbon analysis. The results indicate that the techniques used in tandem can properly delineate the nature and extent of contamination at a site; often supplement or complement data, while reducing the risk of errors and omissions during the assessment phase; and provide data constructively to focus site-specific remediation efforts. 7 figs.

  12. Method for baghouse brown plume pollution control

    Energy Technology Data Exchange (ETDEWEB)

    Hooper, R.G.

    1990-03-13

    This patent describes an SO{sub x}/NO{sub x} air pollution control process employing a baghouse to simultaneously control particulate emissions. It comprises: introducing a sodium-based reagent into a stream of flue gas containing SO{sub x} and NO{sub x}; introducing urea as an additive into the flue gases; maintaining the reagent and the additive in contact with the flue gas to react the reagent with some of the SO{sub x} and NO{sub x} thereby reducing the concentration of the SO{sub x} and NO{sub x} in the flue gas; the additive, as compared to use of the reagent without the additive, increasing the percent SO{sub x} removal and the percent NO{sub x} removal by the reagent while suppressing conversion of NO to NO{sub 2} by the reagent to below about the visible brown plume threshold; and collecting the reacted reagent and additive in a baghouse.

  13. Ash plume top height estimation using AATSR

    Directory of Open Access Journals (Sweden)

    T. H. Virtanen

    2014-08-01

    Full Text Available An algorithm is presented for the estimation of volcanic ash plume top height using the stereo view of the Advanced Along Track Scanning Radiometer (AATSR aboard Envisat. The algorithm is based on matching top of the atmosphere (TOA reflectances and brightness temperatures of the nadir and 55° forward views, and using the resulting parallax to obtain the height estimate. Various retrieval parameters are discussed in detail, several quality parameters are introduced, and post-processing methods for screening out unreliable data have been developed. The method is compared to other satellite observations and in situ data. The proposed algorithm is designed to be fully automatic and can be implemented in operational retrieval algorithms. Combined with automated ash detection using the brightness temperature difference between the 11 and 12 μm channels, the algorithm allows efficient simultaneous retrieval of the horizontal and vertical dispersion of volcanic ash. A case study on the eruption of the Icelandic volcano Eyjafjallajökull in 2010 is presented.

  14. Updated Conceptual Model for the 300 Area Uranium Groundwater Plume

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, John M.; Freshley, Mark D.; Last, George V.; Peterson, Robert E.; Bjornstad, Bruce N.

    2012-11-01

    The 300 Area uranium groundwater plume in the 300-FF-5 Operable Unit is residual from past discharge of nuclear fuel fabrication wastes to a number of liquid (and solid) disposal sites. The source zones in the disposal sites were remediated by excavation and backfilled to grade, but sorbed uranium remains in deeper, unexcavated vadose zone sediments. In spite of source term removal, the groundwater plume has shown remarkable persistence, with concentrations exceeding the drinking water standard over an area of approximately 1 km2. The plume resides within a coupled vadose zone, groundwater, river zone system of immense complexity and scale. Interactions between geologic structure, the hydrologic system driven by the Columbia River, groundwater-river exchange points, and the geochemistry of uranium contribute to persistence of the plume. The U.S. Department of Energy (DOE) recently completed a Remedial Investigation/Feasibility Study (RI/FS) to document characterization of the 300 Area uranium plume and plan for beginning to implement proposed remedial actions. As part of the RI/FS document, a conceptual model was developed that integrates knowledge of the hydrogeologic and geochemical properties of the 300 Area and controlling processes to yield an understanding of how the system behaves and the variables that control it. Recent results from the Hanford Integrated Field Research Challenge site and the Subsurface Biogeochemistry Scientific Focus Area Project funded by the DOE Office of Science were used to update the conceptual model and provide an assessment of key factors controlling plume persistence.

  15. Implementation of microwave transmissions for rocket exhaust plume diagnostics

    Science.gov (United States)

    Coutu, Nicholas George

    Rocket-launched vehicles produce a trail of exhaust that contains ions, free electrons, and soot. The exhaust plume increases the effective conductor length of the rocket. A conductor in the presence of an electric field (e.g. near the electric charge stored within a cloud) can channel an electric discharge. The electrical conductivity of the exhaust plume is related to its concentration of free electrons. The risk of a lightning strike in-flight is a function of both the conductivity of the body and its effective length. This paper presents an approach that relates the electron number density of the exhaust plume to its propagation constant. Estimated values of the collision frequency and electron number density generated from a numerical simulation of a rocket plume are used to guide the design of the experimental apparatus. Test par meters are identified for the apparatus designed to transmit a signal sweep form 4 GHz to 7 GHz through the exhaust plume of a J-class solid rocket motor. Measurements of the scattering parameters imply that the transmission does not penetrate the plume, but instead diffracts around it. The electron density 20 cm downstream from the nozzle exit is estimated to be between 2.7x1014 m--3 and 5.6x10 15 m--3.

  16. The interaction of plume heads with compositional discontinuities in the Earth's mantle

    Science.gov (United States)

    Manga, Michael; Stone, Howard A.; O'Connell, Richard J.

    1993-01-01

    The effects of compositional discontinuities of density and viscosity in the Earth's mantle on the ascent of mantle plume heads is studied using a boundary integral numerical technique. Three specific problems are considered: (1) a plume head rising away from a deformable interface, (2) a plume head passing through an interface, and (3) a plume head approaching the surface of the Earth. For the case of a plume attached to a free-surface, the calculated time-dependent plume shapesare compared with experimental results. Two principle modes of plume head deformation are observed: plume head elingation or the formation of a cavity inside the plume head. The inferred structure of mantle plumes, namely, a large plume head with a long tail, is characteristic of plumes attached to their source region, and also of buoyant material moving away from an interface and of buoyant material moving through an interface from a high- to low-viscosity region. As a rising plume head approaches the upper mantle, most of the lower mantle will quickly drain from the gap between the plume head and the upper mantle if the plume head enters the upper mantle. If the plume head moves from a high- to low-viscosity region, the plume head becomes significantly elongated and, for the viscosity contrasts thought to exist in the Earth, could extend from the 670 km discontinuity to the surface. Plume heads that are extended owing to a viscosity decrease in the upper mantle have a cylindrical geometry. The dynamic surface topography induced by plume heads is bell-shaped when the top of the plume head is at depths greater than about 0.1 plume head radii. As the plume head approaches the surface and spreads, the dynamic topography becomes plateau-shaped. The largest stresses are produced in the early stages of plume spreading when the plume head is still nearly spherical, and the surface expression of these stresses is likely to be dominated by radial extension. As the plume spreads, compressional

  17. Patos Lagoon Outflow Within the Rio de la Plata Plume Using an Airborne Salinity Mapper: Observing an Embedded Plume

    Science.gov (United States)

    2008-01-01

    stress forcing, the Patos plume will be subject to advection and Numerical hydrodynamic model tests are presently being con- shear associated with...changes in the effectiveness of wind and ducted to study the transient behavior of the plumes. These tests , bottom stress as a function of water depth...Brigada de Mantenimiento, Servicio Application of data from near-coincident airborne and in-situ de Sensores Remotos y Aeroespaciales, and Escuadr6n

  18. Amazon Plume Salinity Response to Ocean Teleconnections

    Directory of Open Access Journals (Sweden)

    Pedro Tyaquiçã

    2017-08-01

    Full Text Available Pacific and Atlantic sea surface temperature (SST variability strongly influences rainfall changes in the Amazon River basin, which impacts on the river discharge and consequently the sea surface salinity (SSS in the Amazon plume. An Empirical Orthogonal Function (EOF analysis was performed using 46 years of SST, rainfall, and SSS datasets, in order to establish the relationship between these variables. The first three modes of SST/rainfall explained 87.83% of the total covariance. Pacific and Atlantic SSTs led Amazon basin rainfall events by 4 months. The resultant SSS in the western tropical North Atlantic (WTNA lagged behind basin rainfall by 3 months, with 75.04% of the total covariance corresponding to the first four EOF modes. The first EOF mode indicated a strong SSS pattern along the coast that was connected to negative rainfall anomalies covering the Amazon basin, linked to El Niño events. A second pattern also presented positive SSS anomalies, when the rainfall was predominantly over the northwestern part of the Amazon basin, with low rainfall around the Amazon River mouth. The pattern with negative SSS anomalies in the WTNA was associated with the fourth mode, when positive rainfall anomalies were concentrated in the northwest part of South America. The spatial rainfall structure of this fourth mode was associated with the spatial rainfall distribution found in the third EOF mode of SST vs. rainfall, which was a response to La Niña Modoki events. A statistical analysis for the 46 year period and monthly anomaly composites for 2008 and 2009 indicated that La Niña Modoki events can be used for the prediction of low SSS patterns in the WNTA.

  19. Enceladus Plume Structure and Time Variability: Comparison of Cassini Observations.

    Science.gov (United States)

    Teolis, Ben D; Perry, Mark E; Hansen, Candice J; Waite, J Hunter; Porco, Carolyn C; Spencer, John R; Howett, Carly J A

    2017-09-01

    During three low-altitude (99, 66, 66 km) flybys through the Enceladus plume in 2010 and 2011, Cassini's ion neutral mass spectrometer (INMS) made its first high spatial resolution measurements of the plume's gas density and distribution, detecting in situ the individual gas jets within the broad plume. Since those flybys, more detailed Imaging Science Subsystem (ISS) imaging observations of the plume's icy component have been reported, which constrain the locations and orientations of the numerous gas/grain jets. In the present study, we used these ISS imaging results, together with ultraviolet imaging spectrograph stellar and solar occultation measurements and modeling of the three-dimensional structure of the vapor cloud, to constrain the magnitudes, velocities, and time variability of the plume gas sources from the INMS data. Our results confirm a mixture of both low and high Mach gas emission from Enceladus' surface tiger stripes, with gas accelerated as fast as Mach 10 before escaping the surface. The vapor source fluxes and jet intensities/densities vary dramatically and stochastically, up to a factor 10, both spatially along the tiger stripes and over time between flyby observations. This complex spatial variability and dynamics may result from time-variable tidal stress fields interacting with subsurface fissure geometry and tortuosity beyond detectability, including changing gas pathways to the surface, and fluid flow and boiling in response evolving lithostatic stress conditions. The total plume gas source has 30% uncertainty depending on the contributions assumed for adiabatic and nonadiabatic gas expansion/acceleration to the high Mach emission. The overall vapor plume source rate exhibits stochastic time variability up to a factor ∼5 between observations, reflecting that found in the individual gas sources/jets. Key Words: Cassini at Saturn-Geysers-Enceladus-Gas dynamics-Icy satellites. Astrobiology 17, 926-940.

  20. Laminar and turbulent surgical plume characteristics generated from curved- and straight-blade laparoscopic ultrasonic dissectors.

    Science.gov (United States)

    Kim, Fernando J; Sehrt, David; Pompeo, Alexandre; Molina, Wilson R

    2014-05-01

    To characterize laparoscopic ultrasonic dissector surgical plume emission (laminar or turbulent) and investigate plume settlement time between curved and straight blades. A straight and a curved blade laparoscopic ultrasonic dissector were activated on tissue and in a liquid environment to evaluate plume emission. Plume emission was characterized as either laminar or turbulent and the plume settlement times were compared. Devices were then placed in liquid to observed consistency in the fluid disruption. Two types of plume emission were identified generating different directions of plume: laminar flow causes minimal visual obstruction by directing the aerosol downwards, while turbulent flow directs plume erratically across the cavity. Laminar plume dissipates immediately while turbulent plume reaches a second maximum obstruction approximately 0.3 s after activation and clears after 2 s. Turbulent plume was observed with the straight blade in 10 % of activations, and from the curved blade in 47 % of activations. The straight blade emitted less obstructive plume. Turbulent flow is disruptive to laparoscopic visibility with greater field obstruction and requires longer settling than laminar plume. Ultrasonic dissectors with straight blades have more consistent oscillations and generate more laminar flow compared with curved blades. Surgeons may avoid laparoscope smearing from maximum plume generation depending on blade geometry.

  1. Plume capture by a migrating ridge: Analog geodynamic experiments

    Science.gov (United States)

    Mendez, J. S.; Hall, P.

    2010-12-01

    Paleomagnetic data from the Hawaii-Emperor Seamount Chain (HESC) suggests that the Hawaiian hotspot moved rapidly (~40 mm/yr) between 81 - 47 Ma but has remained relatively stationary since that time. This implies that the iconic bend in the HESC may in fact reflect the transition from a period of rapid hotspot motion to a stationary state, rather than a change in motion of the Pacific plate. Tarduno et al. (2009) have suggested that this period of rapid hotspot motion might be the surface expression of a plume conduit returning to a largely vertical orientation after having been “captured” and tilted by a migrating mid-ocean ridge. We report on a series of analog fluid dynamic experiments designed to characterize the interaction between a migrating spreading center and a thermally buoyant mantle plume. Experiments were conducted in a clear acrylic tank (100 cm x 70 cm x 50 cm) filled with commercial grade high-fructose corn syrup. Plate-driven flow is modeled by dragging two sheets of Mylar film (driven by independent DC motors) in opposite directions over the surface of the fluid. Ridge migration is achieved by moving the point at which the mylar sheets diverge using a separate motor drive. Buoyant plume flow is modeled using corn syrup introduced into the bottom of the tank from an external, heated, pressurized reservoir. Small (~2 mm diameter), neutrally buoyant Delrin spheres are mixed into reservoir of plume material to aid in visualization. Plate velocities and ridge migration rate are controlled and plume temperature monitored using LabView software. Experiments are recorded using digital video which is then analyzed using digital image analysis software to track the position and shape of the plume conduit throughout the course of the experiment. The intersection of the plume conduit with the surface of the fluid is taken as an analog for the locus of hotspot volcanism and tracked as a function of time to obtain a hotspot migration rate. Experiments are

  2. Field experimental observations of highly graded sediment plumes.

    Science.gov (United States)

    Jensen, Jacob Hjelmager; Saremi, Sina; Jimenez, Carlos; Hadjioannou, Louis

    2015-06-15

    A field experiment in the waters off the south-eastern coast of Cyprus was carried out to study near-field formation of sediment plumes from dumping. Different loads of sediment were poured into calm and limpid waters one at the time from just above the sea surface. The associated plumes, gravitating towards the seafloor, were filmed simultaneously by four divers situated at different depths in the water column, and facing the plume at different angles. The processes were captured using GoPro-Hero-series cameras. The high-quality underwater footage from near-surface, mid-depth and near-bed positions gives unique insight into the dynamics of the descending plume and near-field dispersion processes, and enables good understanding of flow and sediment transport processes involved from-release-to-deposition of the load in a non-scaled environment. The high resolution images and footages are available through the link provided herein. Observations support the development of a detailed multi-fractional sediment plume model. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Pyroxenite in the Galapagos plume source at 65 Ma

    Science.gov (United States)

    Whalen, W. T.; Gazel, E.; Vidito, C. A.; Herzberg, C. T.; Class, C.; Bizimis, M.; Alvarado-Induni, G.

    2013-12-01

    Mantle plumes originate from boundary layers below the upper mantle. Their surface expressions as hotspot tracks have been linked to voluminous outpourings of lava in the form of large igneous provinces. The Galapagos hotspot has been active since ~90 Ma and the oldest lavas of its associated submarine ridge have been dated to ~14 Ma, subducting at the Middle America Trench, off Costa Rica. The Galapagos plume head magmatic production is preserved as the Caribbean Large Igneous Province (CLIP). A series of 15-65 Ma accreted Galapagos paleo-ridges and islands/seamounts are accreted in the Pacific coast of Costa Rica and Panama. One of these accreted terranes, the Quepos block on the west coast of Costa Rica is an ancient, ~65 Ma Galapagos island. Olivine phenocrysts from Quepos picrites have elevated Ni and low Ca and Mn and Fe/Mn indicative of a dominant pyroxenite source component while CLIP samples are dominated by a peridotite source. The mantle potential temperature (max) of the plume changed from ~1650 to ~1550 C at 65 Ma. This change correlates with the first appearance of the pyroxenite component and an EMII signature (Northern Galapagos Domain) in the Galapagos plume. A relatively dense pyroxenite component may provide a mechanism for the change in Tp due to its effect on the plume's bouyancy. Alternatively, the pyroxenite component was diluted by high peridotite melt fraction during the massive production of the CLIP.

  4. Magmatic plumbing system from lower mantle of Hainan plume

    Science.gov (United States)

    Xia, Shaohong; Sun, Jinlong; Xu, Huilong; Huang, Haibo; Cao, Jinghe

    2017-04-01

    Intraplate volcanism during Late Cenozoic in the Leiqiong area of southernmost South China, with basaltic lava flows covering a total of more than 7000 km2, has been attributed to an underlying Hainan plume. However, detailed features of Hainan plume, such as morphology of magmatic conduits, depth of magmatic pool in the upper mantle and pattern of mantle upwelling, are still enigmatic. Here we present seismic tomographic images of the upper 1100 km of the mantle beneath the southern South China. Our results show a mushroom-like continuous low-velocity anomaly characterized by a columnar tail with diameter of about 200-300 km that tilts downward to lower mantle beneath north of Hainan hotspot and a head that spreads laterally near the mantle transition zone, indicating a magmatic pool in the upper mantle. Further upward, this head is decomposed into small patches, but when encountering the base of the lithosphere, a pancake-like anomaly is shaped again to feed the Hainan volcanism. Our results challenge the classical model of a fixed thermal plume that rises vertically to the surface, and propose the new layering-style pattern of magmatic upwelling of Hainan plume. This work indicates the spatial complexities and differences of global mantle plumes probably due to heterogeneous compositions and changefully thermochemical structures of deep mantle.

  5. Laser beam-plasma plume interaction during laser welding

    Science.gov (United States)

    Hoffman, Jacek; Moscicki, Tomasz; Szymanski, Zygmunt

    2003-10-01

    Laser welding process is unstable because the keyhole wall performs oscillations which results in the oscillations of plasma plume over the keyhole mouth. The characteristic frequencies are equal to 0.5-4 kHz. Since plasma plume absorbs and refracts laser radiation, plasma oscillations modulate the laser beam before it reaches the workpiece. In this work temporary electron densities and temperatures are determined in the peaks of plasma bursts during welding with a continuous wave CO2 laser. It has been found that during strong bursts the plasma plume over the keyhole consists of metal vapour only, being not diluted by the shielding gas. As expected the values of electron density are about two times higher in peaks than their time-averaged values. Since the plasma absorption coefficient scales as ~N2e/T3/2 (for CO2 laser radiation) the results show that the power of the laser beam reaching the metal surface is modulated by the plasma plume oscillations. The attenuation factor equals 4-6% of the laser power but it is expected that it is doubled by the refraction effect. The results, together with the analysis of the colour pictures from streak camera, allow also interpretation of the dynamics of the plasma plume.

  6. Jet plume injection and combustion system for internal combustion engines

    Science.gov (United States)

    Oppenheim, Antoni K.; Maxson, James A.; Hensinger, David M.

    1993-01-01

    An improved combustion system for an internal combustion engine is disclosed wherein a rich air/fuel mixture is furnished at high pressure to one or more jet plume generator cavities adjacent to a cylinder and then injected through one or more orifices from the cavities into the head space of the cylinder to form one or more turbulent jet plumes in the head space of the cylinder prior to ignition of the rich air/fuel mixture in the cavity of the jet plume generator. The portion of the rich air/fuel mixture remaining in the cavity of the generator is then ignited to provide a secondary jet, comprising incomplete combustion products which are injected into the cylinder to initiate combustion in the already formed turbulent jet plume. Formation of the turbulent jet plume in the head space of the cylinder prior to ignition has been found to yield a higher maximum combustion pressure in the cylinder, as well as shortening the time period to attain such a maximum pressure.

  7. Infrared signature characteristic of a microturbine engine exhaust plume

    Science.gov (United States)

    Gu, Bonchan; Baek, Seung Wook; Jegal, Hyunwook; Choi, Seong Man; Kim, Won Cheol

    2017-11-01

    This research investigates the infrared signature of the exhaust plume ejected from a microturbine engine. Circular and square nozzles are designed and tested to study their effects on the resultant infrared signature of the plume. A microturbine engine is operated under steady conditions with a kerosene added lubricant oil as a fuel. The measurements of the infrared signature are conducted using a spectroradiometer. Blackbody radiance is also measured at an arbitrary temperature and compared to theoretical values to validate the reference and to calibrate the raw spectrum. The infrared signatures emitted from the plume are measured at three measurement locations along the plume for two nozzle configurations. The results are grouped into sub-bands to examine and discuss their specific spectral characteristics. The infrared signatures are shown to decrease as the distance from the nozzle exit increases, which is attributed to the hot exhaust plume mixing with ambient air. The degree to which the signature is reduced at the different the measurement locations was dependent on the sub-band. Comparison of the results shows that the infrared signature of the square nozzle is lower than that of the circular nozzle in specific bands.

  8. Using the GPS SNR Technique to Detect Volcanic Plumes

    Science.gov (United States)

    Naik, S. R.; Mattia, M.; Larson, K. M.; Rossi, M.; Bruno, V.; Coltelli, M.; Ohta, Y.; Schneider, D. J.

    2015-12-01

    Detection of volcanic plumes, especially ash-laden ones, is important both for public health and aircraft safety. A variety of geophysical tools and satellite data are used to monitor volcanic eruptions and to predict the movement of ash. However, satellite-based methods are restricted by time of day and weather, while radars are often unavailable because of cost/ portability. GPS instruments are frequently deployed near volcanos, but typically they have only been used to measure deformation. Here a method is proposed to detect volcanic plumes using GPS signal to noise ratio (SNR) data. The strengths and limitations of the method are assessed using GPS data collected during eruptions at Mt. Redoubt (2009) and Mt. Etna (2013). Plume detections are compared with independently collected seismic and radar data.

  9. Quantification of Asian Dust Plume Seasonal Dynamics and Regional Features

    Science.gov (United States)

    Goetz, Michael

    2011-01-01

    Dust is but one of many aerosols that are analyzed at the Jet Propulsion Laboratory in Pasadena. The purpose of this paper is to describe the process in analyzing and digitizing dust within a source region to better explain the work achieved by my internship. This paper will go over how to view collected data by Multi-angle Imaging SpectroRadiometer (MISR) [1] and the procedure of downloading data to be analyzed. With this data, one can digitize dust plumes using two methods called plume lines and plume polygons with the help of the software MISR INteractive eXplorer (MINX)[3]; thus, the theory of MINX's[3] algorithm and these methods are discussed in detail. Research was gathered from these techniques and emphasis is also focused on the obtained data and results.

  10. Satellite detection of wastewater diversion plumes in Southern California

    Science.gov (United States)

    Gierach, Michelle M.; Holt, Benjamin; Trinh, Rebecca; Jack Pan, B.; Rains, Christine

    2017-02-01

    Multi-sensor satellite observations proved useful in detecting surfacing wastewater plumes during the 2006 Hyperion Treatment Plant (HTP) and 2012 Orange County Sanitation District (OCSD) wastewater diversion events in Southern California. Satellite sensors were capable of detecting biophysical signatures associated with the wastewater, compared to ambient ocean waters, enabling monitoring of environmental impacts over a greater spatial extent than in situ sampling alone. Thermal satellite sensors measured decreased sea surface temperatures (SSTs) associated with the surfacing plumes. Ocean color satellite sensors did not measure a distinguishable biological response in terms of chlorophyll-a (chl-a) concentrations during the short lived, three-day long, 2006 HTP diversion. A period of decreased chl-a concentration was observed during the three-week long 2012 OCSD diversion, likely in association with enhanced chlorination of the discharged wastewater that suppressed the phytoplankton response and/or significant uptake by heterotrophic bacteria. Synthetic aperture radar (SAR) satellite data were able to identify and track the 2006 HTP wastewater plume through changes in surface roughness related to the oily components of the treated surfacing wastewater. Overall, it was found that chl-a and SST values must have differences of at least 1 mg m-3 and 0.5 °C, respectively, in comparison with adjacent waters for wastewater plumes and their biophysical impact to be detectable from satellite. For a wastewater plume to be identifiable in SAR imagery, wind speeds must range between ∼3 and 8 m s-1. The findings of this study illustrate the benefit of utilizing multiple satellite sensors to monitor the rapidly changing environmental response to surfacing wastewater plumes, and can help inform future wastewater diversions in coastal areas.

  11. Subducting Plate Breakup by Plume-Lithosphere Interaction

    Science.gov (United States)

    Koptev, A.; Gerya, T.; Jolivet, L.; Leroy, S. D.

    2016-12-01

    We use a 3D high-resolution thermo-mechanical modeling to investigate the impact of active mantle plume on a subducting lithospheric plate. Initial model setup consists of an overriding continental lithosphere and subducting lithospheric plate including oceanic and continental lithosphere. A mantle plume thermal anomaly has been initially seeded at the bottom of the model box underneath the continental segment of subducting plate. Mantle plume impingement on lithospheric bottom leads to thinning of continental lithosphere and decompressional melting of both lithospheric and sublithospheric mantle along stretched trench-parallel zone. Further continental breakup is followed by opening of an oceanic basin separating a newly formed microcontinent from the main subducting continent. Despite continuous push applied at the boundary of subducting plate, plume-induced oceanic basin opens during several Myrs reaching several hundred kilometers wide. Cooling of the mantle plume and beginning of collision between the separated microcontinent and the overriding continental plate lead to gradual closure of newly formed oceanic basin that gets further involved into subduction and collision. The final stage sees continental subduction of main body of subducting plate and simultaneous tectonic exhumation of the upper crust of the subducted microcontinent. This scenario involving a plume-induced rifting of a microcontinent away from main body of subducted plate can be compared to the Mesozoic-Cenozoic development of the African plate characterized by the consecutive separation of the Apulian microcontinent and Arabian plate (in the Jurassic and the Neogene, respectively) during subduction of Neo-Tethys oceanic lithosphere beneath the Eurasian margin.

  12. Tidally induced lateral dispersion of the Storfjorden overflow plume

    Directory of Open Access Journals (Sweden)

    F. Wobus

    2013-10-01

    Full Text Available We investigate the flow of brine-enriched shelf water from Storfjorden (Svalbard into Fram Strait and onto the western Svalbard Shelf using a regional set-up of NEMO-SHELF, a 3-D numerical ocean circulation model. The model is set up with realistic bathymetry, atmospheric forcing, open boundary conditions and tides. The model has 3 km horizontal resolution and 50 vertical levels in the sh-coordinate system which is specially designed to resolve bottom boundary layer processes. In a series of modelling experiments we focus on the influence of tides on the propagation of the dense water plume by comparing results from tidal and non-tidal model runs. Comparisons of non-tidal to tidal simulations reveal a hotspot of tidally induced horizontal diffusion leading to the lateral dispersion of the plume at the southernmost headland of Spitsbergen which is in close proximity to the plume path. As a result the lighter fractions in the diluted upper layer of the plume are drawn into the shallow coastal current that carries Storfjorden water onto the western Svalbard Shelf, while the dense bottom layer continues to sink down the slope. This bifurcation of the plume into a diluted shelf branch and a dense downslope branch is enhanced by tidally induced shear dispersion at the headland. Tidal effects at the headland are shown to cause a net reduction in the downslope flux of Storfjorden water into the deep Fram Strait. This finding contrasts previous results from observations of a dense plume on a different shelf without abrupt topography.

  13. IASI measurements of reactive trace species in biomass burning plumes

    Directory of Open Access Journals (Sweden)

    P.-F. Coheur

    2009-08-01

    Full Text Available This work presents observations of a series of short-lived species in biomass burning plumes from the Infrared Atmospheric Sounding Interferometer (IASI, launched onboard the MetOp-A platform in October 2006. The strong fires that have occurred in the Mediterranean Basin – and particularly Greece – in August 2007, and those in Southern Siberia and Eastern Mongolia in the early spring of 2008 are selected to support the analyses. We show that the IASI infrared spectra in these fire plumes contain distinctive signatures of ammonia (NH3, ethene (C2H4, methanol (CH3OH and formic acid (HCOOH in the atmospheric window between 800 and 1200 cm−1, with some noticeable differences between the plumes. Peroxyacetyl nitrate (CH3COOONO2, abbreviated as PAN was also observed with good confidence in some plumes and a tentative assignment of a broadband absorption spectral feature to acetic acid (CH3COOH is made. For several of these species these are the first reported measurements made from space in nadir geometry. The IASI measurements are analyzed for plume height and concentration distributions of NH3, C2H4 and CH3OH. The Greek fires are studied in greater detail for the days associated with the largest emissions. In addition to providing information on the spatial extent of the plume, the IASI retrievals allow an estimate of the total mass emissions for NH3, C2H4 and CH3OH. Enhancement ratios are calculated for the latter relative to carbon monoxide (CO, giving insight in the chemical processes occurring during the transport, the first day after the emission.

  14. Synchronized Lunar Pole Impact Plume Sample Return Trajectory Design

    Science.gov (United States)

    Genova, Anthony L.; Foster, Cyrus; Colaprete, Tony

    2016-01-01

    The presented trajectory design enables two maneuverable spacecraft launched onto the same trans-lunar injection trajectory to coordinate a steep impact of a lunar pole and subsequent sample return of the ejecta plume to Earth. To demonstrate this concept, the impactor is assumed to use the LCROSS missions trajectory and spacecraft architecture, thus the permanently-shadowed Cabeus crater on the lunar south pole is assumed as the impact site. The sample-return spacecraft is assumed to be a CubeSat that requires a complimentary trajectory design that avoids lunar impact after passing through the ejecta plume to enable sample-return to Earth via atmospheric entry.

  15. Temperature fluctuation of the Iceland mantle plume through time

    OpenAIRE

    Spice, Holly E.; Fitton, John; Kirstein, Linda

    2016-01-01

    The newly developed Al-in-olivine geothermometer was used to find the olivine-Cr-spinel crystallization temperatures of a suite of picrites spanning the spatial and temporal extent of the North Atlantic Igneous Province (NAIP), which is widely considered to be the result of a deep-seated mantle plume. Our data confirm that start-up plumes are associated with a pulse of anomalously hot mantle over a large spatial area before becoming focused into a narrow upwelling. We find that the thermal an...

  16. Monitoring Groundwater Contaminant Plumes Using Airborne Geophysical Data

    Science.gov (United States)

    Robinson, Martin; Oftendinger, Ulrich; Ruffell, Alastair; Cowan, Marie; Cassidy, Rachel; Comte, Jean-Christophe; Wilson, Christopher; Desissa, Mohammednur

    2013-04-01

    Under the European Union Water Framework Directive, Member States are required to assess water quality across both surface water and groundwater bodies. Subsurface pollution plumes, originating from a variety of sources, pose a significant direct risk to water quality. The monitoring and characterisation of groundwater contaminant plumes is generally invasive, time consuming and expensive. In particular, adequately capturing the contaminant plume with monitoring installations, when the extent of the feature is unknown and the presence of contamination is only evident from indirect observations, can be prohibitively expensive. This research aims to identify the extent and nature of subsurface contaminant plumes using airborne geophysical survey data. This data was collected across parts of the island of Ireland within the scope of the original Tellus and subsequent Tellus Border projects. The rapid assessment of the airborne electro-magnetic (AEM) data allowed the identification of several sites containing possible contaminant plumes. These AEM anomalies were assessed through the analysis of existing site data and field site inspections, with areas of interest being examined for metallic structures that could affect the AEM data. Electrical resistivity tomography (ERT), ground penetrating radar (GPR) and ground-based electro-magnetic (EM) surveys were performed to ground-truth existing airborne data and to confirm the extent and nature of the affected area identified using the airborne data. Groundwater and surface water quality were assessed using existing field site information. Initial results collected from a landfill site underlain by basalt have indicated that the AEM data, coupled with ERT and GPR, can successfully be used to locate possible plumes and help delineate their extent. The analysis of a range of case study sites exhibiting different geological and environmental settings will allow for the development of a consistent methodology for examining the

  17. Spatial and temporal characterization of methane plumes from mobile platforms

    Science.gov (United States)

    O'Brien, A.; Wendt, L.; Miller, D. J.; Lary, D. J.; Zondlo, M. A.

    2013-12-01

    The spatial and temporal characterization of methane plumes from hydraulic fracturing well sites are presented. Methane measurements from the Marcellus shale region obtained using a commercial instrument on a motor vehicle are discussed. Over 100 well sites in the region were sampled and the methane signature in the vicinity of these wells is presented. Additionally, measurements of methane from our open-path instrument flown aboard the UT Dallas AMR Payload Master 100 remote-controlled, electric aircraft in the Barnett shale region are presented. Using our observations of aircraft surveys near well sites and a gaussian plume dispersion model emission estimates of fugitive methane are presented.

  18. Insights into Coignimbrite Plume Dynamics from Numerical Models

    Science.gov (United States)

    Engwell, S. L.; De'Michieli Vitturi, M.; Barsotti, S.; Eychenne, J.; Esposti Ongaro, T.; Neri, A.

    2014-12-01

    Great advances have been made in recent years to better understand and model the processes that occur in Plinian plumes. However, comparatively little work has been conducted on modeling coignimbrite plumes, which form as fine-grained material is lofted from the top of pyroclastic density currents, rising into the atmosphere due to buoyancy. This fundamental difference in source condition (gas thrust vs. buoyancy) means that the parameters used to describe Plinian plumes, for example initial source radius, upwards velocity, temperature, gas mass fraction and grain-size distribution are not appropriate for modeling coignimbrite events. In this study, the ash flow model of Bursik and Woods (1996) is coupled with a plume model (Bursik 2001, Barsotti et al. 2008) to investigate the controls on coignimbrite plume formation, and once formed, the height and dynamics of the plume. Sensitivity analysis was conducted using DAKOTA software and results show that source temperature and gas mass fraction play a key role in controlling when 'lift-off' occurs. Once formed, maximum plume height is controlled by the source radius, the temperature at 'liftoff' and the entrainment assumption. Finally, we use the May 18th 1980 Mount St. Helens co-blast eruption to test the application of an ash dispersion model, specifically VOLCALPUFF (Barsotti et al., 2008), to the coignimbrite problem, with the specific aim of distinguishing differences in application for coignimbrite and Plinian events. The results highlight the importance of coignimbrite events when considering ash fall hazard and a requirement to treat such events separately to Plinian events. Andrews, B.J. and Manga, M.. JVGR , 225-226, 30-44, 2012 Barsotti, S, Neri, A, and Scire, JS. The vol-calpuff model for atmospheric ash dispersal: 1. Approach and physical formulation. JGR, 113(B03208), 2008 Bursik, M. Effect of wind on the rise height of volcanic plumes. GRL, 28(18), 3621-3624, 2001. Bursik, M and Woods, A. W. The dynamics

  19. Plume Mitigation: Soil Erosion and Lunar Prospecting Sensor Project

    Science.gov (United States)

    Metzger, Philip T.

    2014-01-01

    Demonstrate feasibility of the simplest, lowest-mass method of measuring density of a cloud of lunar soil ejected by rocket exhaust, using new math techniques with a small baseline laser/camera system. Focus is on exploring the erosion process that occurs when the exhaust plume of a lunar rocket impacts the regolith. Also, predicting the behavior of the lunar soil that would be blasted from a lunar landing/launch site shall assist in better design and protection of any future lunar settlement from scouring of structures and equipment. NASA is gathering experimental data to improve soil erosion models and understand how lunar particles enter the plume flow.

  20. Plume-rift interaction in the Deccan volcanic province

    Science.gov (United States)

    Sheth, H. C.; Chandrasekharam, D.

    1997-02-01

    It is widely accepted that the grand volcanic episode of the Deccan in India was a consequence of the passage of the northerly drifting Indian subcontinent over the Réunion starting plume in the Late Cretaceous. This plume also produced the three-rift Cambay triple junction, the three arms being the West Coast graben belt, the Narmada-Tapi rift zone and the Cambay rift. Deccan-related alkalic magmatism both preceded and followed the main tholeiitic phase of ˜ 65 Ma ago by about 3 MY. The uniformly tholeiitic thick basalt sequence of the Western Ghats was derived from direct melting of the plume head, but the tholeiitic-alkalic magmatism of the three rift belts was due to melting of the hydrous lithospheric mantle due to variable amounts of rifting. Any lithospheric loading mechanism for generating post-tholeiite alkalic lavas does not seem feasible for the Deccan; nor can it explain the pre-tholeiite alkaline magmatism in the Deccan. Similarly, conductive heating of the lithosphere by the plume cannot have generated the alkalic melts. Some amount of actual rifting did occur. Direct melt supply from the plume is not necessary for magmatism in the rifts, though it seems to have occurred in some cases. Our documentation of indigenous magmatism for the three rift belts calls into question any attempts at inferring the size of the plume head from synchroneity in geochronologic data alone, and we negate the possibility or necessity of large-distance transport of magmas from the plume through the lithosphere, to feed the rifts. Recent evidence indicates that alkalic magmatism north of the main Deccan outcrop preceded the main tholeiite phase by ˜ 3 MY. The Cambay graben was active 3.5 MY before the main tholeiite phase. As the alkalic complexes at the northern end of this graben are 68.5 Ma in age (so far the oldest well-proven Deccan-related rocks), they are the first expression of the Réunion plume, and the borehole picrites from the triple junction area, until now

  1. Mixing between a stratospheric intrusion and a biomass burning plume

    Directory of Open Access Journals (Sweden)

    J. Brioude

    2007-08-01

    Full Text Available Ozone, carbon monoxide, aerosol extinction coefficient, acetonitrile, nitric acid and relative humidity measured from the NOAA P3 aircraft during the TexAQS/GoMACCS 2006 experiment, indicate mixing between a biomass burning plume and a stratospheric intrusion in the free troposphere above eastern Texas. Lagrangian-based transport analysis and satellite imagery are used to investigate the transport mechanisms that bring together the tropopause fold and the biomass burning plume originating in southern California, which may affect the chemical budget of tropospheric trace gases.

  2. Direct Measurement of Mercury Reactions In Coal Power Plant Plumes

    Energy Technology Data Exchange (ETDEWEB)

    Leonard Levin

    2005-12-31

    Recent field and pilot-scale results indicate that divalent mercury emitted from power plants may rapidly transform to elemental mercury within the power plant plumes. Simulations of mercury chemistry in plumes based on measured rates to date have improved regional model fits to Mercury Deposition Network wet deposition data for particular years, while not degrading model verification fits for remaining years of the ensemble. The years with improved fit are those with simulated deposition in grid cells in the State of Pennsylvania that have matching MDN station data significantly less than the model values. This project seeks to establish a full-scale data basis for whether or not significant reduction or oxidation reactions occur to mercury emitted from coal-fired power plants, and what numerical redox rate should apply for extension to other sources and for modeling of power plant mercury plumes locally, regionally, and nationally. Although in-stack mercury (Hg) speciation measurements are essential to the development of control technologies and to provide data for input into atmospheric fate and transport models, the determination of speciation in a cooling coal combustion plume is more relevant for use in estimating Hg fate and effects through the atmosphere. It is mercury transformations that may occur in the plume that determine the eventual rate and patterns of mercury deposited to the earth's surface. A necessary first step in developing a supportable approach to modeling any such transformations is to directly measure the forms and concentrations of mercury from the stack exit downwind to full dispersion in the atmosphere. As a result, a study was sponsored by EPRI and jointly funded by EPRI, the U.S Department of Energy (DOE), and the Wisconsin Department of Administration. The study was designed to further our understanding of plume chemistry. The study was carried out at the We Energies Pleasant Prairie Power Plant, Pleasant Prairie, Wisconsin

  3. STUDIES OF TWO-PHASE PLUMES IN STRATIFIED ENVIRONMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Scott A. Socolofsky; Brian C. Crounse; E. Eric Adams

    1998-11-18

    Two-phase plumes play an important role in the more practical scenarios for ocean sequestration of CO{sub 2}--i.e. dispersing CO{sub 2} as a buoyant liquid from either a bottom-mounted or ship-towed pipeline. Despite much research on related applications, such as for reservoir destratification using bubble plumes, our understanding of these flows is incomplete, especially concerning the phenomenon of plume peeling in a stratified ambient. To address this deficiency, we have built a laboratory facility in which we can make fundamental measurements of plume behavior. Although we are using air, oil and sediments as our sources of buoyancy (rather than CO{sub 2}), by using models, our results can be directly applied to field scale CO{sub 2} releases to help us design better CO{sub 2} injection systems, as well as plan and interpret the results of our up-coming international field experiment. The experimental facility designed to study two-phase plume behavior similar to that of an ocean CO{sub 2} release includes the following components: 1.22 x 1.22 x 2.44 m tall glass walled tank; Tanks and piping for the two-tank stratification method for producing step- and linearly-stratified ambient conditions; Density profiling system using a conductivity and temperature probe mounted to an automated depth profiler; Lighting systems, including a virtual point source light for shadowgraphs and a 6 W argon-ion laser for laser induced fluorescence (LIF) imaging; Imaging system, including a digital, progressive scanning CCD camera, computerized framegrabber, and image acquisition and analysis software; Buoyancy source diffusers having four different air diffusers, two oil diffusers, and a planned sediment diffuser; Dye injection method using a Mariotte bottle and a collar diffuser; and Systems integration software using the Labview graphical programming language and Windows NT. In comparison with previously reported experiments, this system allows us to extend the parameter range of

  4. Sediment plume response to surface melting and supraglacial lake drainages on the Greenland ice sheet

    DEFF Research Database (Denmark)

    Chu, Vena W.; Smith, Laurence C; Rennermalm, Asa K.

    2009-01-01

    of a downstream sediment plume in Kangerlussuaq Fjord by comparing: (1) plume area and suspended sediment concentration from Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and field data; (2) ice-sheet melt extent from Special Sensor Microwave/Imager (SSM/I) passive microwave data; and (3......) supraglacial lake drainage events from MODIS. Results confirm that the origin of the sediment plume is meltwater release from the ice sheet. Interannual variations in plume area reflect interannual variations in surface melting. Plumes appear almost immediately with seasonal surface-melt onset, provided...... the estuary is free of landfast sea ice. A seasonal hysteresis between melt extent and plume area suggests late-season exhaustion in sediment supply. Analysis of plume sensitivity to supraglacial events is less conclusive, with 69% of melt pulses and 38% of lake drainage events triggering an increase in plume...

  5. The impact of glacier geometry on meltwater plume structure and submarine melt in Greenland fjords

    NARCIS (Netherlands)

    Carroll, D.; Sutherland, D. A.; Hudson, B.; Moon, T.; Catania, G. A.; Shroyer, E. L.; Nash, J. D.; Bartholomaus, T. C.; Felikson, D.; Stearns, L. A.; Noël, B. P Y; van den Broeke, M. R.

    2016-01-01

    Meltwater from the Greenland Ice Sheet often drains subglacially into fjords, driving upwelling plumes at glacier termini. Ocean models and observations of submarine termini suggest that plumes enhance melt and undercutting, leading to calving and potential glacier destabilization. Here we

  6. Stochastic Mapping for Chemical Plume Source Localization With Application to Autonomous Hydrothermal Vent Discovery

    National Research Council Canada - National Science Library

    Jakuba, Michael V

    2007-01-01

    ..., explosive ordinance removal, and hydrothermal vent prospecting. Turbulent flows make the spatial relationship between the detectable manifestation of a chemical plume source, the plume itself, and the location of its source inherently uncertain...

  7. Modeling the Effects of Aircraft Emissions on Atmospheric Photochemistry Using Layered Plume Dynamics

    Science.gov (United States)

    Cameron, M. A.; Jacobson, M. Z.; Naiman, A. D.; Lele, S. K.

    2012-12-01

    Aviation is an expanding industry, experiencing continued growth and playing an increasingly noticed role in upper tropospheric/lower stratospheric composition. Nitrogen oxides and other gas-phase emissions from aircraft react to affect ozone photochemistry. This research investigates the effects of treating aircraft gas-phase chemistry within an expanding layered plume versus at the grid scale. SMVGEAR II, a sparse-matrix, vectorized Gear-type solver for ordinary differential equations, is used to solve chemical equations at both the grid scale and subgrid scale. A Subgrid Plume Model (SPM) is used to advance the expanding plume, accounting for wind shear and diffusion. Simulations suggest that using a layered plume approach results in noticeably different final NOx concentrations, demonstrating the importance of these plume dynamics in predicting the effects of aircraft on ozone concentrations. Results showing the effects of a layered plume, single plume, and no plume on ozone after several hours will be presented.

  8. The effects of particulates on supersonic shear layers and afterburning in fuel-rich plumes

    OpenAIRE

    Lee, Siwon R.

    1995-01-01

    An investigation was conducted to experimentally quantify the interaction of particulates with the fuel-rich plume flowfield typical for solid propellant rocket motors. This was done in order to optimize enhanced mixing devices or chemical-additive addition for afterburning suppression. Laser sheet flow visualization, sound spectra measurements, plume thermal images and particle size distribution measurements were utilized with reacting and non- reacting gaseous plumes and with the plumes fro...

  9. Observations of brine plumes below melting Arctic sea ice

    Directory of Open Access Journals (Sweden)

    A. K. Peterson

    2018-02-01

    Full Text Available In sea ice, interconnected pockets and channels of brine are surrounded by fresh ice. Over time, brine is lost by gravity drainage and flushing. The timing of salt release and its interaction with the underlying water can impact subsequent sea ice melt. Turbulence measurements 1 m below melting sea ice north of Svalbard reveal anticorrelated heat and salt fluxes. From the observations, 131 salty plumes descending from the warm sea ice are identified, confirming previous observations from a Svalbard fjord. The plumes are likely triggered by oceanic heat through bottom melt. Calculated over a composite plume, oceanic heat and salt fluxes during the plumes account for 6 and 9 % of the total fluxes, respectively, while only lasting in total 0.5 % of the time. The observed salt flux accumulates to 7.6 kg m−2, indicating nearly full desalination of the ice. Bulk salinity reduction between two nearby ice cores agrees with accumulated salt fluxes to within a factor of 2. The increasing fraction of younger, more saline ice in the Arctic suggests an increase in desalination processes with the transition to the new Arctic.

  10. Hydrothermal plumes over the Carlsberg Ridge, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ray, D.; KameshRaju, K.A; Baker, E.T.; Rao, A; Mudholkar, A; Lupton, J.E.; SuryaPrakash, L.; Gawas, R.B.; VijayaKumar, T.

    Water column surveys and sampling in 2007 and 2009 was conducted to search for hydrothermal plumes over a segment of the Carlsberg Ridge. An evidence for two separate vent fields, one near 3 degrees 42′N, 63 degrees 40′E and another near 3 degrees...

  11. Solar Coronal Plumes and the Fast Solar Wind

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Before the spectroscopic peculiarities in IPRs and plumes in Polar Coronal Holes (PCHs) can be further investigated with the instrument Solar Ultraviolet Measurements of Emitted Radiation (SUMER) aboard the Solar and Heliospheric Observatory (SOHO), it is mandatory to summarize the results of the ...

  12. MODELING AN IRRITANT GAS PLUME FOR EPIDEMIOLOGIC STUDY

    Science.gov (United States)

    Jani, Dev D.; Reed, David; Feigley, Charles E.

    2015-01-01

    Plume dispersion modeling systems are often used in assessing human exposures to chemical hazards for epidemiologic study. We modeled the 2005 Graniteville, South Carolina, 54,915 kg railcar chlorine release using both the Areal Locations of Hazardous Atmospheres (ALOHA) and Hazard Prediction and Assessment Capability (HPAC) plume modeling systems. We estimated the release rate by an engineering analysis combining semi-quantitative observations and fundamental physical principles. The use of regional meteorological conditions was validated by comparing concentration estimates generated by two source-location weather data sets. The HPAC model estimated a chlorine plume with 20 ppm outdoor concentrations up to 7 km downwind and 0.25 km upwind/downgrade. A comparative analysis of our two models showed that HPAC was the best candidate for use as a model system on which epidemiologic studies could be based after further model validation. Further validation studies are needed before individual exposure estimates can be reliable and the chlorine plume more definitively modeled. PMID:25772143

  13. Global volcanic emissions: budgets, plume chemistry and impacts

    Science.gov (United States)

    Mather, T. A.

    2012-12-01

    Over the past few decades our understanding of global volcanic degassing budgets, plume chemistry and the impacts of volcanic emissions on our atmosphere and environment has been revolutionized. Global volcanic emissions budgets are needed if we are to make effective use of regional and global atmospheric models in order to understand the consequences of volcanic degassing on global environmental evolution. Traditionally volcanic SO2 budgets have been the best constrained but recent efforts have seen improvements in the quantification of the budgets of other environmentally important chemical species such as CO2, the halogens (including Br and I) and trace metals (including measurements relevant to trace metal atmospheric lifetimes and bioavailability). Recent measurements of reactive trace gas species in volcanic plumes have offered intriguing hints at the chemistry occurring in the hot environment at volcanic vents and during electrical discharges in ash-rich volcanic plumes. These reactive trace species have important consequences for gas plume chemistry and impacts, for example, in terms of the global fixed nitrogen budget, volcanically induced ozone destruction and particle fluxes to the atmosphere. Volcanically initiated atmospheric chemistry was likely to have been particularly important before biological (and latterly anthropogenic) processes started to dominate many geochemical cycles, with important consequences in terms of the evolution of the nitrogen cycle and the role of particles in modulating the Earth's climate. There are still many challenges and open questions to be addressed in this fascinating area of science.

  14. Multiphase CFD modeling of nearfield fate of sediment plumes

    DEFF Research Database (Denmark)

    Saremi, Sina; Hjelmager Jensen, Jacob

    2014-01-01

    . The two-phase mixture solution based on the drift-flux method is evaluated for 3D simulation of material disposal and overflow discharge from the hoppers. The model takes into account the hindrance and resistance mechanisms in the mixture and is capable of describing the flow details within the plumes...

  15. Impacts of wildfire smoke plumes on regional air quality

    Science.gov (United States)

    Background: Recent trends in increased frequency and severity of large fires necessitate an improved understanding of smoke plume impacts on regional-scale air quality and public health. Objective: We examine the impact of fire smoke on regional air quality between 2006 and 2013 ...

  16. Sulfur balance in power plant plumes: a critical review

    Science.gov (United States)

    William E. Wilson

    1976-01-01

    Numerous attempts have been made to measure the rate of loss of SO2 in power plant plumes. If SO2 decreases more rapidly than an inert pollutant, the control measures necessary to meet SO2 standards would be eased. More recently, Swedish studies of acid rain, thought to be due to long range transport...

  17. Midwave Infrared Imaging Fourier Transform Spectrometry of Combustion Plumes

    Science.gov (United States)

    2009-09-01

    reside most prominently in the LWIR, the MWIR is well-suited for analysis of combustion plumes, including industrial emissions and jet engine exhaust...Appl.Opt., 14:1423–1428, 1975. [81] Weibring, P., M. Andersson, H. Edner, and S. Svanberg. “Remote monitoring of industrial emissions by combination of

  18. Atmospheric ventilation corridors and coefficients for pollution plume ...

    African Journals Online (AJOL)

    This study presents a comparative investigation of atmospheric ventilation corridors and coefficients for gaseous pollution plume released from an isolated industrial facility into the ambient air of the host community in Ile-Ife suburb, southwest Nigeria. For the months of September to December in the year 2012 and 2013, ...

  19. The EUV Spectrum of Sunspot Plumes Observed by SUMER on ...

    Indian Academy of Sciences (India)

    tribpo

    J. Astrophys. Astr. (2000) 21, .397-401. The EUV Spectrum of Sunspot Plumes Observed by SUMER on. SOHO. W. Curdt,. 1. B. N. Dwivedi. 2. & U. Feldman. 3. 1. Max-Planck-Institut für Aeronomie, D-37191, Katlenburg-Lindau, Germany. 2. Department of Applied Physics, Banaras Hindu University, Varanasi-221005, India.

  20. The Growth and Decay of Equatorial Backscatter Plumes.

    Science.gov (United States)

    1980-02-01

    spatially connected to bottomside backscatter, a feature noted in Jica- marca radar observations that led Woodman and La Hoz (1976) to speculate that...described in Section Ill-B, this pattern of plume growth resembles the "C-shaped" and "fishtail" patterns found in Jica- marca radar RTI displays of 50-MHz

  1. Laser ablation plume expansion into an ambient gas

    DEFF Research Database (Denmark)

    Amoruso, S.; Schou, Jørgen; Lunney, J.G.

    2009-01-01

    The use of an ambient gas is a well-established method employed in pulsed laser deposition (PLD) with nanosecond pulses and has been extensively studied in this context. Most of the existing treatments of the plume expansion are tackled by using complex numerical modeling involving specific target...

  2. Contaminant plumes containment and remediation focus area. Technology summary

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-01

    EM has established a new approach to managing environmental technology research and development in critical areas of interest to DOE. The Contaminant Plumes Containment and Remediation (Plumes) Focus Area is one of five areas targeted to implement the new approach, actively involving representatives from basic research, technology implementation, and regulatory communities in setting objectives and evaluating results. This document presents an overview of current EM activities within the Plumes Focus Area to describe to the appropriate organizations the current thrust of the program and developing input for its future direction. The Plumes Focus Area is developing remediation technologies that address environmental problems associated with certain priority contaminants found at DOE sites, including radionuclides, heavy metals, and dense non-aqueous phase liquids (DNAPLs). Technologies for cleaning up contaminants of concern to both DOE and other federal agencies, such as volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), and other organics and inorganic compounds, will be developed by leveraging resources in cooperation with industry and interagency programs.

  3. Field experimental observations of highly graded sediment plumes

    DEFF Research Database (Denmark)

    Hjelmager Jensen, Jacob; Saremi, Sina; Jimenez, Carlos

    2015-01-01

    , gravitating towards the seafloor, were filmed simultaneously by four divers situated at different depths in the water column, and facing the plume at different angles. The processes were captured using GoPro-Hero-series cameras. The high-quality underwater footage from near-surface, mid-depth and near...

  4. Modelling the Zambezi River plume | Nehama | African Journal of ...

    African Journals Online (AJOL)

    typical of observed discharge amounts in summer), the Kelvin and Froude numbers for the resulting plume imply a 'large-scale' buoyant discharge with a coastal current that is close to being in geostrophic balance with the across-shore pressure ...

  5. A Plume Tracing, Source Identifying Technique for Mars Rovers

    Science.gov (United States)

    Banfield, Don; Lamb, Brian; Hovde, Chris; Ferrara, Tom

    2015-11-01

    We have developed and field-tested a technique to identify and characterize the source of an effluent plume (biogenic or otherwise) on Mars, using a slow-moving vehicle like a Mars Rover. The technique is based on terrestrial plume characterization methods (EPA Method 33a), and uses puff models of variable complexity to predict the plume behavior for a given source. The technique is developed assuming that a Mars Rover would be equipped with a high-performance eddy-sensing 3-D anemometer (e.g., a Martian Sonic Anemometer), as well as a fast-response tracer molecule-specific sensor (e.g., a TLS methane sensor). The platform is assumed to move only once a day, but have the ability to observe throughout the day and night. Data obtained from any one sol while the effluent plume meanders across the rover can be used to estimate the azimuth, range and strength of the source, but combining observations from multiple sols and locations is used to improve the estimate of the souce location and strength.We have conducted preliminary field tests using a Sonic Anemometer (Gill and Campbell) and fast-response methane sensors (LICOR and Picarro) on mobile platforms using both controlled and existing methane releases to prove our algorithm in simple terrain, and with varying atmospheric stability. We will discuss our results and the efficacy of our algorithm in real world conditions.

  6. Apollo Video Photogrammetry Estimation Of Plume Impingement Effects

    Science.gov (United States)

    Immer, Christopher; Lane, John; Metzger, Philip T.; Clements, Sandra

    2008-01-01

    The Constellation Project's planned return to the moon requires numerous landings at the same site. Since the top few centimeters are loosely packed regolith, plume impingement from the Lander ejects the granular material at high velocities. Much work is needed to understand the physics of plume impingement during landing in order to protect hardware surrounding the landing sites. While mostly qualitative in nature, the Apollo Lunar Module landing videos can provide a wealth of quantitative information using modem photogrammetry techniques. The authors have used the digitized videos to quantify plume impingement effects of the landing exhaust on the lunar surface. The dust ejection angle from the plume is estimated at 1-3 degrees. The lofted particle density is estimated at 10(exp 8)- 10(exp 13) particles per cubic meter. Additionally, evidence for ejection of large 10-15 cm sized objects and a dependence of ejection angle on thrust are presented. Further work is ongoing to continue quantitative analysis of the landing videos.

  7. Fallugia paradoxa (D. Don) Endl. ex Torr.: Apache-plume

    Science.gov (United States)

    Susan E. Meyer

    2008-01-01

    The genus Fallugia contains a single species - Apache-plume, F. paradoxa (D. Don) Endl. ex Torr. - found throughout the southwestern United States and northern Mexico. It occurs mostly on coarse soils on benches and especially along washes and canyons in both warm and cool desert shrub communities and up into the pinyon-juniper vegetation type. It is a sprawling, much-...

  8. Heat and mass transfer in the mushroom-shaped head of mantle plume

    Directory of Open Access Journals (Sweden)

    Kirdyashkin Anatoly

    2017-01-01

    Full Text Available The results of experimental and theoretical modeling of free-convection flows in the melt of the plume conduit and in the mushroom-shaped head are presented. It was shown that the plumes with the mushroom-shaped heads can be responsible for the batholith formation. The main parameters of such plumes are estimated.

  9. A two-way interaction between the Hainan plume and the Manila subduction zone

    NARCIS (Netherlands)

    Mériaux, Catherine A.; Duarte, João C.; Schellart, Wouter P.; Mériaux, Anne Sophie

    2015-01-01

    The interaction between mantle plumes and subducting slabs is well accepted, but the influence of slabs on plumes has more often been portrayed than the reverse. Here we present three-dimensional upper mantle laboratory models in which a compositional plume rises underneath a subducting plate.

  10. Bubbles generated from wind-steepened breaking waves: 2. Bubble plumes, bubbles, and wave characteristics

    NARCIS (Netherlands)

    Leifer, I.; Caulliez, G.; Leeuw, G.de

    2006-01-01

    Measurements of breaking-wave-generated bubble plumes were made in fresh (but not clean) water in a large wind-wave tunnel. To preserve diversity, a classification scheme was developed on the basis of plume dimensions and "optical density," or the plume's ability to obscure the background. Optically

  11. Water tank measurements of buoyant plume rise and structure in neutral crossflows

    National Research Council Canada - National Science Library

    Contini, Daniele; Robins, Alan

    2001-01-01

    ..., especially under favourable wind directions. Reliable analytical models exist for single plume rise evaluation (e.g. Briggs, 1974, 1975a, b ), as well as integral models that relate the plume mass and momentum fluxes to the forces acting on a plume and the entrainment rate of external fluid (e.g. Ooms and Mahieu, 1981 ; Robins and Aspley, 1994 )...

  12. Ionospheric Irregularities Predictions and Plumes Characterization for Satellite Data Validation and Calibration

    Science.gov (United States)

    2014-01-17

    AFRL-OSR-VA-TR-2014-0082 IONOSPHERIC IRREGULARITIES PREDICTIONS AND PLUMES CHARACTERIZATION FOR SATELLITE Eurico De Paula FUNCATE - FUNDACACAO DE... Ionospheric Irregularities Predictions and Plumes Characterization for Satellite Data Validation and Calibration 5a. CONTRACT NUMBER... Ionospheric Irregularities Predictions and Plumes Characterization for Satellite Data Validation and Calibration 5b. GRANT NUMBER FA9550-10-1-0564

  13. A parameter model for dredge plume sediment source terms

    Science.gov (United States)

    Decrop, Boudewijn; De Mulder, Tom; Toorman, Erik; Sas, Marc

    2017-01-01

    The presented model allows for fast simulations of the near-field behaviour of overflow dredging plumes. Overflow dredging plumes occur when dredging vessels employ a dropshaft release system to discharge the excess sea water, which is pumped into the trailing suction hopper dredger (TSHD) along with the dredged sediments. The fine sediment fraction in the loaded water-sediment mixture does not fully settle before it reaches the overflow shaft. By consequence, the released water contains a fine sediment fraction of time-varying concentration. The sediment grain size is in the range of clays, silt and fine sand; the sediment concentration varies roughly between 10 and 200 g/l in most cases, peaking at even higher value with short duration. In order to assess the environmental impact of the increased turbidity caused by this release, plume dispersion predictions are often carried out. These predictions are usually executed with a large-scale model covering a complete coastal zone, bay, or estuary. A source term of fine sediments is implemented in the hydrodynamic model to simulate the fine sediment dispersion. The large-scale model mesh resolution and governing equations, however, do not allow to simulate the near-field plume behaviour in the vicinity of the ship hull and propellers. Moreover, in the near-field, these plumes are under influence of buoyancy forces and air bubbles. The initial distribution of sediments is therefore unknown and has to be based on crude assumptions at present. The initial (vertical) distribution of the sediment source is indeed of great influence on the final far-field plume dispersion results. In order to study this near-field behaviour, a highly-detailed computationally fluid dynamics (CFD) model was developed. This model contains a realistic geometry of a dredging vessel, buoyancy effects, air bubbles and propeller action, and was validated earlier by comparing with field measurements. A CFD model requires significant simulation times

  14. Plume-induced roll back subduction around Venus large coronae

    Science.gov (United States)

    Davaille, A.; Smrekar, S. E.; Tomlinson, S. M.

    2016-12-01

    On Venus, possible subduction trenches are mainly associated with large coronae, eventhough the latter are thought to be produced by hot mantle plumes. The mechanism of assocation between subduction and plume has long remained elusive. However, we recently observe the same association in laboratory experiments on thermal convection in colloidal aqueous dispersions of silica nanoparticles, which deform in the Newtonian regime at low solid particle fraction φp, and transition to strain-rate weakening, plasticity, elasticity, and brittle properties as φp increases. Hence, a dense skin akin to a planetary lithosphere grows on the surface when the system is dried from above. When a hot plume rises under the skin, the latter undergoes a flexural deformation which puts it under tension. Cracks then develop, sometimes using pre-existing weaknesses. Plume material (being more buoyant that the laboratory lithosphere) upwells through the cracks and spreads as a axisymmetric gravity current above the broken denser skin. The latter bends and sinks under the conjugate action of its own weight and the plume gravity current. The brittle character of the top experimental lithosphere forbids it to deform viscously to accomodate the sinking motions. Instead, the plate continues to tear as a sheet of paper would do upon intrusion. Several slabs are therefore produced, associated with trenches localized along partial circles on the plume, and strong roll-back is always observed. Depending on the lithospheric strength, roll-back can continue and triggers a complete resurfacing, or it stops when the plume stops spreading. Scalings derived from the experiments suggest that a weaker lithosphere than that present on Earth today is required for such a convective regime. We identified two candidates on Venus. At Artemis and Quetzelpetlatl Coronae, the radar image observations and subsurface density variations inferred from modeling the gravity and topography agree with the predictions from

  15. Plumes and Earth's Dynamic History : from Core to Biosphere

    Science.gov (United States)

    Courtillot, V. E.

    2002-12-01

    The last half century has been dominated by the general acceptance of plate tectonics. Although the plume concept emerged early in this story, its role has remained ambiguous. Because plumes are singularities, both in space and time, they tend to lie dangerously close to catastrophism, as opposed to the calm uniformitarian view of plate tectonics. Yet, it has become apparent that singular events and transient phenomena are of great importance, even if by definition they cover only a small fraction of geological time, in diverse observational and theoretical fields such as 1) magnetic reversals and the geodynamo, 2) tomography and mantle convection, 3) continental rifting and collision, and 4) evolution of the fluid envelopes (atmospheric and oceanic "climate"; evolution of species in the biosphere). I will emphasize recent work on different types of plumes and on the correlation between flood basalts and mass extinctions. The origin of mantle plumes remains a controversial topic. We suggest that three types of plumes exist, which originate at the three main discontinuities in the Earth's mantle (base of lithosphere, transition zone and core-mantle boundary). Most of the hotspots are short lived (~ 10Ma) and seem to come from the transition zone or above. Important concentrations occur above the Pacific and African superswells. Less than 10 hotspots have been long lived (~ 100Ma) and may have a very deep origin. In the last 50 Ma, these deep-seated plumes in the Pacific and Indo-Atlantic hemispheres have moved slowly, but motion was much faster prior to that. This change correlates with major episodes of true polar wander. The deeper ("primary") plumes are thought to trace global shifts in quadrupolar convection in the lower mantle. These are the plumes that were born as major flood basalts or oceanic plateaus (designated as large igneous provinces or LIPs). Most have an original volume on the order or in excess of 2.5 Mkm3. In most provinces, volcanism lasted on

  16. Mapping of plume deposits and surface composition on Enceladus

    Science.gov (United States)

    Nordheim, T. A.; Scipioni, F.; Cruikshank, D. P.; Clark, R. N.,; Hand, K. P.

    2017-01-01

    A major result of the Cassini mission was the discovery that the small mid-sized moon Enceladus is presently geological active[Dougherty et al., 2006; Porco et al., 2006; Spencer et al., 2006; Hansen et al., 2008]. This activity results in plumes of water vapor and ice emanating from a series of fractures ("Tiger Stripes") at the moon's South Pole. Some fraction of plume material escapes the moon's gravity and populates the E-ring as well as ultimately providing a source of fresh plasma in the Saturnian magnetosphere [Pontius and Hill, 2006; Kempf et al., 2010]. However, a significant portion of plume material is redeposited on Enceladus and thus provides a source of surface contaminants. By studying the near-infrared spectral signatures of these contaminants we may put new constraints on the composition of the plumes and, ultimately, their source, which is currently believed to be Enceladus's global sub-surface ocean [Iess et al., 2014]. Here we present preliminary results from our analysis of observations from the Visual and Infrared Mapping Spectrometer (VIMS) [Brown et al., 2005] onboard Cassini and mapping of plume deposits across the surface of Enceladus. We have investigated the global variation of the water ice Fresnel peak at 3.1 μm, which may be used as an indicator of ice crystallinity [Hansen & McCord, 2004; Jaumann et al., 2008; Newman et al., 2008]. We have also investigated the slope of the 1.11-2.25 μm spectral region, which serves as an indicator of water ice grain size for small grains (contaminants [e.g. Filacchione et al., 2010]. Finally, we have identified and mapped an absorption feature centered at 3.25 μm that may be related to organic contaminants, represented by the band depth of the fundamental C-H stretch [e.g. Cruikshank et al., 2014; Scipioni et al., 2014].

  17. Analysis of GOSAT XCO2 in explosive volcanic plumes

    Science.gov (United States)

    Popp, Christoph; Andrews, Benjamin J.; Carn, Simon A.; Chance, Kelly; Cottrell, Elizabeth; Schwandner, Florian M.

    2014-05-01

    In this study, we analyze columnar averaged dry air mole fraction of CO2 (XCO2) in volcanic gas plumes after major eruptions using space-borne near-infrared measurements from the Japanese Greenhouse gas Observing SATellite (GOSAT). Volcanic emissions are assumed to dominate the flux from the deep Earth to the surface but those global emissions as well as the partitioning between eruptive and non-eruptive emissions are to date highly uncertain. Satellite measurements are an indispensable complement to ground-based measurements of volcanic CO2 emissions because they are performed globally and regularly and they therefore have the potential to significantly broaden our knowledge of volcanic CO2 releases. However, the remote sensing of volcanic CO2 is challenging for various reasons, including the increasingly high atmospheric background, relatively coarse spatial resolution and/or sampling, and scattering effects of aerosols and clouds. We mined existing standard product level 2 GOSAT XCO2 data sets for a volcanic CO2 signal in the gas plumes of the largest volcanic eruptions since GOSAT's launch in 2009. These eruptions include the Volcanic Explosivity Index (VEI) 4 events of Sarychev Peak (Kuril Islands, Russia) in June 2009, Nabro (Ethiopia) in June 2011, and Puyehue-Cordon Caulle (Chile) in June 2011. GOSAT background and plume soundings are distinguished using corresponding Ozone Monitoring Instrument (OMI) SO2 retrievals taking advantage of the usually low atmospheric SO2 background abundance. A volcanic CO2 signal in the GOSAT products can subsequently be found by comparing GOSAT XCO2 for the plume and background soundings. Possible XCO2 enhancements in the volcanic plumes are converted to an estimated CO2 release of the investigated eruptions. Based on this analysis, the current capabilities and added value of GOSAT TANSO-FTS to detect and quantify CO2 emissions from explosive volcanism are outlined.

  18. Reconciling the Misfit Between the Yellowstone Plume Trace and Global Plate Motion Models: Channelized and Pancake Plume Flow on Basal Lithospheric Topography

    Science.gov (United States)

    Jordan, B. T.

    2001-12-01

    Age-progrssive rhyolitic volcanism from the Owyhee Plateau along the Snake River Plain to the Yellowstone Plateau is widely interpreted as reflecting the motion of the North American plate over a mantle plume. The strongest line of evidence against this interpretation is the misfit between the length of the interpreted plume trace and the length predicted by global plate motion models. As generally represented, the plume trace extends 700 km from the 16.1 Ma McDermitt Caldera to the caldera of the 0.6 Ma Lava Creek Tuff at Yellowstone. Global plate motion models predict a plume trace of 190-340 km in 16 m.y. Extension immediately south of the Snake River Plain has been estimated at 20%, well short of the >100% required to reconcile the misfit. Also complicating the plume interpretation is the position of the feeder dikes of the Columbia River basalts (CRB), widely interpreted as the result of emplacement of the head of the Yellowstone plume, >300 km north of the interpreted plume trace at 16 Ma. Both of these problems can be reconciled by considering the complex results of interaction of a mantle plume with basal lithospheric topography. The predicted position of the plume at 16 Ma, based on plate motion models plus extension, was near the southern end of the Snake River Plain, under thick Precambrian lithosphere. Thinner lithosphere occurred 150 to 200 km west of this point at the boundary with Paleozoic and Mesozoic accreted terranes. The CRB, Steens Basalts (SB), and Northern Nevada Rift (NNR) basalts were erupted through the accreted terranes west of this boundary beginning about 16.5 Ma. Two processes could link this basaltic volcanism to the plume: (1) assuming the plume head was >600 km in diameter, some plume head material would have risen to shallow depths and undergone decompression melting under CRB and SB dikes and the NNR; and (2) flow of plume head and conduit-fed material up a basal lithospheric gradient from under the cratonic lithosphere toward the

  19. Recycled crust in the Galápagos Plume source at 70 Ma: Implications for plume evolution

    Science.gov (United States)

    Trela, Jarek; Vidito, Christopher; Gazel, Esteban; Herzberg, Claude; Class, Cornelia; Whalen, William; Jicha, Brian; Bizimis, Michael; Alvarado, Guillermo E.

    2015-09-01

    Galápagos plume-related lavas in the accreted terranes of the Caribbean and along the west coast of Costa Rica and Panama provide evidence on the evolution of the Galápagos mantle plume, specifically its mantle temperature, size and composition of heterogeneities, and dynamics. Here we provide new 40Ar/39Ar ages, major and trace element data, Sr-Nd-Pb isotopic compositions, and high-precision olivine analyses for samples from the Quepos terrane (Costa Rica) to closely examine the transitional phase of the Galápagos Plume from Large Igneous Province (LIP) to ocean island basalt (OIB) forming stages. The new ages indicate that the record of Quepos volcanism began at 70 Ma and persisted for 10 Ma. Petrological evidence suggests that the maximum mantle potential temperature (Tp) of the plume changed from ∼1650° to ∼1550 °C between 90-70 Ma. This change correlates with a dominant pyroxenite component in the Galapagos source as indicated by high Ni and Fe/Mn and low Ca olivines relative to those that crystallized in normal peridotite derived melts. The decrease in Tp also correlates with an increase in high-field strength element enrichments, e.g., Nb/Nb*, of the erupted lavas. Radiogenic isotope ratios (Nd-Pb) suggest that the Quepos terrane samples have intermediate (Central Domain) radiogenic signatures. The Galápagos plume at 70 Ma represents elevated pyroxenite melt productivity relative to peridotite in a cooling lithologically heterogeneous mantle.

  20. Dynamics of plumes in a compressible mantle with phase changes: Implications for phase boundary topography

    Science.gov (United States)

    Bossmann, Andrea B.; van Keken, Peter E.

    2013-11-01

    While plumes rising from the deep mantle may be responsible for hotspot volcanism, their existence has not yet been unambiguously confirmed by seismological studies. Several seismic studies reported that the topography of the 670-km discontinuity is flat below hotspots, which disagrees with the elevation expected due to its negative Clapeyron slope and plume excess temperature. An improved numerical method that includes compressibility and consistently implemented phase transitions is used to study plume evolution in the Earth’s mantle. The influence of latent heat on plume behavior for varying convective vigor and Clapeyron slope of the endothermic phase change at 670 km depth is studied in axisymmetric spherical shell geometry. Minor differences in plume dynamics are found for models considering and neglecting latent heat. Three regimes of plume behavior at the endothermic phase boundary are observed: besides complete plume inhibition and penetration along the symmetry axis an intermediate regime in which the plume forms a ring around the symmetry axis is found. These models also predict that the 670-km discontinuity is flat below hotspots due to a large plume head in the lower mantle of about 1000 km diameter that significantly thins as it rises into the upper mantle. This is explained by the lower viscosity in the upper mantle and the spreading of the temporarily inhibited plume below the endothermic phase boundary, which reconciles the flat 670-km discontinuity with a deep mantle plume origin.

  1. Predicting the visibility of a chemical vapor plume using schlieren optics

    Science.gov (United States)

    Bigger, Rory; Settles, Gary

    2008-11-01

    Chemicals plumes from a freely-evaporating liquid surface and from the exit of a circular pipe are considered. For the freely-evaporating case, the visibility of fourteen chemicals was tested in two schlieren optical systems. One system was a modest bench-top system and the other was a lard system of extraordinary sensitivity. Plume visibility was found to be a function of the vapor pressure and vapor refractive index. An empirical fit to the plume-visibility data, compared with the sensitivities of these systems (measured using a standard-lens method), suggests guidelines for predicting the visibility of plumes of other chemicals using other schlieren equipment. For the circular opening case, plume visibility of the same chemicals was found to be a function of plume geometry and refractive index. The peak light-ray deflections (also measured with a standard lens) caused by plumes of two different sizes were found to scale based on plume geometry. This scaling information and plume refractive index can be used to predict plume visibility for arbitrary chemicals in arbitrary systems, if the system sensitivity is known. One application of this work lies in the optical detection of plumes emitted by contraband material.

  2. Wedge Shock and Nozzle Exhaust Plume Interaction in a Supersonic Jet Flow

    Science.gov (United States)

    Castner, Raymond; Zaman, Khairul; Fagan, Amy; Heath, Christopher

    2014-01-01

    Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the nozzle exhaust plume. Aft body shock waves that interact with the exhaust plume contribute to the near-field pressure signature of a vehicle. The plume and shock interaction was studied using computational fluid dynamics and compared with experimental data from a coaxial convergent-divergent nozzle flow in an open jet facility. A simple diamond-shaped wedge was used to generate the shock in the outer flow to study its impact on the inner jet flow. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the opposite plume boundary. The sonic boom pressure signature of the nozzle exhaust plume was modified by the presence of the wedge. Both the experimental results and computational predictions show changes in plume deflection.

  3. Integration of Engine, Plume, and CFD Analyses in Conceptual Design of Low-Boom Supersonic Aircraft

    Science.gov (United States)

    Li, Wu; Campbell, Richard; Geiselhart, Karl; Shields, Elwood; Nayani, Sudheer; Shenoy, Rajiv

    2009-01-01

    This paper documents an integration of engine, plume, and computational fluid dynamics (CFD) analyses in the conceptual design of low-boom supersonic aircraft, using a variable fidelity approach. In particular, the Numerical Propulsion Simulation System (NPSS) is used for propulsion system cycle analysis and nacelle outer mold line definition, and a low-fidelity plume model is developed for plume shape prediction based on NPSS engine data and nacelle geometry. This model provides a capability for the conceptual design of low-boom supersonic aircraft that accounts for plume effects. Then a newly developed process for automated CFD analysis is presented for CFD-based plume and boom analyses of the conceptual geometry. Five test cases are used to demonstrate the integrated engine, plume, and CFD analysis process based on a variable fidelity approach, as well as the feasibility of the automated CFD plume and boom analysis capability.

  4. Multi-sensor Mapping of Volcanic Plumes and Clouds

    Science.gov (United States)

    Realmuto, V. J.

    2006-12-01

    The instruments aboard the NASA series of Earth Observing System satellites provide a rich suite of measurements for the mapping of volcanic plumes and clouds. In this presentation we focus on analyses of data acquired with the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Atmospheric Infrared Sounder (AIRS), Moderate-Resolution Imaging Spectrometer (MODIS), and Multiangle Imaging SpectroRadiometer (MISR). ASTER, MODIS, AIRS, and MISR provide complimentary information on the quantity and distribution of sulfur dioxide, silicate ash, and sulfate aerosols within plumes. In addition, MISR data are used to derive estimates of cloud-top altitude, wind direction, and wind speed. The key to multi-sensor mapping is the availability of a standard set of tools for the processing of data from different instruments. To date we have used the MAP_SO2 toolkit to analyze the thermal infrared (TIR) data from MODIS, ASTER, and AIRS. MAP_SO2, a graphic user interface to the MODTRAN radiative transfer model, provides tools for the estimation of emissivity spectra, water vapor and ozone correction factors, surface temperature, and concentrations of SO2. We use the MISR_Shift toolkit to estimate plume-top altitudes and local wind vectors. Our continuous refinement of MAP_SO2 has resulted in lower detection limits for SO2 and lower sensitivity to the presence of sulfate aerosols and ash. Our plans for future refinements of MAP_SO2 include the incorporation of AIRS-based profiles of atmospheric temperature, water vapor and ozone, and MISR-based maps of plume-top altitude into the plume mapping procedures. The centerpiece of our study is a time-series of data acquired during the 2002-2003 and 2006 eruptions of Mount Etna. Time-series measurements are the only means of recording dynamic phenomena and characterizing the processes that generate such phenomena. We have also analyzed data acquired over Klychevskoy, Bezymianny, and Sheveluch (Kamchatka), Augustine

  5. Plume trajectory formation under stack tip self-enveloping

    Science.gov (United States)

    Gribkov, A. M.; Zroichikov, N. A.; Prokhorov, V. B.

    2017-10-01

    The phenomenon of stack tip self-enveloping and its influence upon the conditions of plume formation and on the trajectory of its motion are considered. Processes are described occurring in the initial part of the plume while the interaction between vertically directed flue gases outflowing from the stack and a horizontally directed moving air flow at high wind velocities that lead to the formation of a flag-like plume. Conditions responsible for the origin and evolution of interaction between these flows are demonstrated. For the first time, a plume formed under these conditions without bifurcation is registered. A photo image thereof is presented. A scheme for the calculation of the motion of a plume trajectory is proposed, the quantitative characteristics of which are obtained based on field observations. The wind velocity and direction, air temperature, and atmospheric turbulence at the level of the initial part of the trajectory have been obtained based on data obtained from an automatic meteorological system (mounted on the outer parts of a 250 m high stack no. 1 at the Naberezhnye Chelny TEPP plant) as well as based on the results of photographing and theodolite sighting of smoke puffs' trajectory taking into account their velocity within its initial part. The calculation scheme is supplemented with a new acting force—the force of self-enveloping. Based on the comparison of the new calculation scheme with the previous one, a significant contribution of this force to the development of the trajectory is revealed. A comparison of the natural full-scale data with the results of the calculation according to the proposed new scheme is made. The proposed calculation scheme has allowed us to extend the application of the existing technique to the range of high wind velocities. This approach would make it possible to simulate and investigate the trajectory and full rising height of the calculated the length above the mouth of flue-pipes, depending on various modal

  6. Estimation of Eruption Source Parameters from Plume Growth Rate

    Science.gov (United States)

    Pouget, Solene; Bursik, Marcus; Webley, Peter; Dehn, Jon; Pavalonis, Michael; Singh, Tarunraj; Singla, Puneet; Patra, Abani; Pitman, Bruce; Stefanescu, Ramona; Madankan, Reza; Morton, Donald; Jones, Matthew

    2013-04-01

    The eruption of Eyjafjallajokull, Iceland in April and May, 2010, brought to light the hazards of airborne volcanic ash and the importance of Volcanic Ash Transport and Dispersion models (VATD) to estimate the concentration of ash with time. These models require Eruption Source Parameters (ESP) as input, which typically include information about the plume height, the mass eruption rate, the duration of the eruption and the particle size distribution. However much of the time these ESP are unknown or poorly known a priori. We show that the mass eruption rate can be estimated from the downwind plume or umbrella cloud growth rate. A simple version of the continuity equation can be applied to the growth of either an umbrella cloud or the downwind plume. The continuity equation coupled with the momentum equation using only inertial and gravitational terms provides another model. Numerical modeling or scaling relationships can be used, as necessary, to provide values for unknown or unavailable parameters. Use of these models applied to data on plume geometry provided by satellite imagery allows for direct estimation of plume volumetric and mass growth with time. To test our methodology, we compared our results with five well-studied and well-characterized historical eruptions: Mount St. Helens, 1980; Pinatubo, 1991, Redoubt, 1990; Hekla, 2000 and Eyjafjallajokull, 2010. These tests show that the methodologies yield results comparable to or better than currently accepted methodologies of ESP estimation. We then applied the methodology to umbrella clouds produced by the eruptions of Okmok, 12 July 2008, and Sarychev Peak, 12 June 2009, and to the downwind plume produced by the eruptions of Hekla, 2000; Kliuchevsko'i, 1 October 1994; Kasatochi 7-8 August 2008 and Bezymianny, 1 September 2012. The new methods allow a fast, remote assessment of the mass eruption rate, even for remote volcanoes. They thus provide an additional path to estimation of the ESP and the forecasting

  7. Experiments on the rise and mixing in neutral crossflow of plumes from two identical sources for different wind directions

    National Research Council Canada - National Science Library

    Contini, Daniele; Robins, Alan

    2004-01-01

    ..., that create distortions of the plume cross-sectional shape and additional-rise or “downwash” with respect to single source cases with zero interaction. As a matter of fact, the interaction that modifies both plume trajectories and plume shapes is due to three different contributions: the partial entrainment of plume material, instead of ambient fluid, ...

  8. Volcanic tremor and plume height hysteresis from Pavlof Volcano, Alaska.

    Science.gov (United States)

    Fee, David; Haney, Matthew M; Matoza, Robin S; Van Eaton, Alexa R; Cervelli, Peter; Schneider, David J; Iezzi, Alexandra M

    2017-01-06

    The March 2016 eruption of Pavlof Volcano, Alaska, produced an ash plume that caused the cancellation of more than 100 flights in North America. The eruption generated strong tremor that was recorded by seismic and remote low-frequency acoustic (infrasound) stations, including the EarthScope Transportable Array. The relationship between the tremor amplitudes and plume height changes considerably between the waxing and waning portions of the eruption. Similar hysteresis has been observed between seismic river noise and discharge during storms, suggesting that flow and erosional processes in both rivers and volcanoes can produce irreversible structural changes that are detectable in geophysical data. We propose that the time-varying relationship at Pavlof arose from changes in the tremor source related to volcanic vent erosion. This relationship may improve estimates of volcanic emissions and characterization of eruption size and intensity. Copyright © 2017, American Association for the Advancement of Science.

  9. High-order harmonic generation in laser plasma plumes

    CERN Document Server

    Ganeev, Rashid A

    2013-01-01

    This book represents the first comprehensive treatment of high-order harmonic generation in laser-produced plumes, covering the principles, past and present experimental status and important applications. It shows how this method of frequency conversion of laser radiation towards the extreme ultraviolet range matured over the course of multiple studies and demonstrated new approaches in the generation of strong coherent short-wavelength radiation for various applications. Significant discoveries and pioneering contributions of researchers in this field carried out in various laser scientific centers worldwide are included in this first attempt to describe the important findings in this area of nonlinear spectroscopy. "High-Order Harmonic Generation in Laser Plasma Plumes" is a self-contained and unified review of the most recent achievements in the field, such as the application of clusters (fullerenes, nanoparticles, nanotubes) for efficient harmonic generation of ultrashort laser pulses in cluster-containin...

  10. Modelling the plasma plume of an assist source in PIAD

    Science.gov (United States)

    Wauer, Jochen; Harhausen, Jens; Foest, Rüdiger; Loffhagen, Detlef

    2016-09-01

    Plasma ion assisted deposition (PIAD) is a technique commonly used to produce high-precision optical interference coatings. Knowledge regarding plasma properties is most often limited to dedicated scenarios without film deposition. Approaches have been made to gather information on the process plasma in situ to detect drifts which are suspected to cause limits in repeatability of resulting layer properties. Present efforts focus on radiance monitoring of the plasma plume of an Advanced Plasma Source (APSpro, Bühler) by optical emission spectroscopy to provide the basis for an advanced plasma control. In this contribution modelling results of the plume region are presented to interpret these experimental data. In the framework of the collisional radiative model used, 15 excited neutral argon states in the plasma are considered. Results of the species densities show good consistency with the measured optical emission of various argon 2 p - 1 s transitions. This work was funded by BMBF under grant 13N13213.

  11. Energy sources for Triton's geyser-like plumes

    Science.gov (United States)

    Brown, R. H.; Johnson, T. V.; Kirk, R. L.; Soderblom, L. A.

    1990-01-01

    Four geyser-like plumes were discovered near Triton's south pole in areas now in permanent sunlight. Because Triton's southern hemisphere is nearing a maximum summer solstice, insolation as a driver or a trigger for Triton's geyser-like plumes is an attractive hypothesis. Trapping of solar radiation in a translucent, low-conductivity surface layer (in a solid-state greenhouse), which is subsequently released in the form of latent heat of sublimation, could provide the required energy. Both the classical solid-state greenhouse consisting of exponentially absorbed insolation in a gray, translucent layer of solid nitrogen, and the 'super' greenhouse consisting of a relatively transparent solid-nitrogen layer over an opaque, absorbing layer are plausible candidates. Geothermal heat may also play a part if assisted by the added energy input of seasonal cycles of insolation.

  12. Preliminary disposal limits, plume interaction factors, and final disposal limits

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2018-01-11

    In the 2008 E-Area Performance Assessment (PA), each final disposal limit was constructed as the product of a preliminary disposal limit and a plume interaction factor. The following mathematical development demonstrates that performance objectives are generally expected to be satisfied with high confidence under practical PA scenarios using this method. However, radionuclides that experience significant decay between a disposal unit and the 100-meter boundary, such as H-3 and Sr-90, can challenge performance objectives, depending on the disposed-of waste composition, facility geometry, and the significance of the plume interaction factor. Pros and cons of analyzing single disposal units or multiple disposal units as a group in the preliminary disposal limits analysis are also identified.

  13. A Plume Scale Model of Chlorinated Ethene Degradation

    DEFF Research Database (Denmark)

    Murray, Alexandra Marie; Broholm, Mette Martina; Badin, Alice

    Although much is known about the biotic degradation pathways of chlorinated solvents, application of the degradation mechanism at the field scale is still challenging [1]. There are many microbial kinetic models to describe the reductive dechlorination in soil and groundwater, however none of them...... leaked from a dry cleaning facility, and a 2 km plume extends from the source in an unconfined aquifer of homogenous fluvio-glacial sand. The area has significant iron deposits, most notably pyrite, which can abiotically degrade chlorinated ethenes. The source zone underwent thermal (steam) remediation...... in 2006; the plume has received no treatment. The evolution of the site has been intensely documented since before the source treatment. This includes microbial analysis – Dehalococcoides sp. and vcrA genes have been identified and quantified by qPCR – and dual carbon-chlorine isotope analysis [1...

  14. Rayleigh scattering in supersonic high-temperature exhaust plumes

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, L.Y. [Institute for Aerospace Research, National Research Council Canada, Ottawa (Canada); Sislian, J.P. [Institute for Aerospace Studies, University of Toronto, ON (Canada)

    2002-04-01

    A supersonic exhaust plume test rig and a Rayleigh scattering system were developed. Molecular number densities in the supersonic high-temperature exhaust plume with and without an annular base flow were investigated. The physical meaning of the inferred mean temperature from the number density measurement in turbulent flows is clarified. For both flows, the potential core extends up to about six nozzle diameters, and self-similarity of the radial density distributions is observed at downstream sections Z/d=10-50. The recovery of the flow density deficit (or the decay of temperature) with the annular flow is faster than that without the annular flow at upstream sections Z/d {<=} 10. (orig.)

  15. Time resolved Nomarski interferometery of laser produced plasma plumes

    Energy Technology Data Exchange (ETDEWEB)

    Hough, P. [School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland)], E-mail: padraighough@gmail.com; McLoughlin, C.; Kelly, T.J. [School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland); Harilal, S.S. [Prism Computational Sciences, Inc., 455 Science Drive, Suite 140, Madison, WI 53711 (United States); Mosnier, J.P.; Costello, J.T. [School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland)

    2009-03-01

    We report results from optical interferometric probing of a laser generated Zn plasma plume. The experiment was performed in a vacuum and O{sub 2} rich environments where the background pressure of O{sub 2} was maintained at 1000 Pa and the results from both regimes are compared. The focus of our work is very much on the early stages in the life of the plasma plume which remains, to date, a largely unexplored area of study, at least in the pulsed laser deposition research domain. It was found that the electron density profile normal to the target is different in the background gas at early times ({approx}30 ns) compared to that of the vacuum case. At later times ({approx}80 ns) both profiles have a very similar shape. We also observe the formation of a shock wave at the plasma-gas interface shortly after plasma breakdown (<15 ns)

  16. Time resolved Nomarski interferometery of laser produced plasma plumes

    Science.gov (United States)

    Hough, P.; McLoughlin, C.; Kelly, T. J.; Harilal, S. S.; Mosnier, J. P.; Costello, J. T.

    2009-03-01

    We report results from optical interferometric probing of a laser generated Zn plasma plume. The experiment was performed in a vacuum and O 2 rich environments where the background pressure of O 2 was maintained at 1000 Pa and the results from both regimes are compared. The focus of our work is very much on the early stages in the life of the plasma plume which remains, to date, a largely unexplored area of study, at least in the pulsed laser deposition research domain. It was found that the electron density profile normal to the target is different in the background gas at early times (˜30 ns) compared to that of the vacuum case. At later times (˜80 ns) both profiles have a very similar shape. We also observe the formation of a shock wave at the plasma-gas interface shortly after plasma breakdown (<15 ns).

  17. Experimental Investigation of Large-Scale Bubbly Plumes

    Energy Technology Data Exchange (ETDEWEB)

    Zboray, R.; Simiano, M.; De Cachard, F

    2004-03-01

    Carefully planned and instrumented experiments under well-defined boundary conditions have been carried out on large-scale, isothermal, bubbly plumes. The data obtained is meant to validate newly developed, high-resolution numerical tools for 3D transient, two-phase flow modelling. Several measurement techniques have been utilised to collect data from the experiments: particle image velocimetry, optical probes, electromagnetic probes, and visualisation. Bubble and liquid velocity fields, void-fraction distributions, bubble size and interfacial-area-concentration distributions have all been measured in the plume region, as well as recirculation velocities in the surrounding pool. The results obtained from the different measurement techniques have been compared. In general, the two-phase flow data obtained from the different techniques are found to be consistent, and of high enough quality for validating numerical simulation tools for 3D bubbly flows. (author)

  18. Meteorology of Jupiter's Equatorial Hot Spots and Plumes from Cassini

    Science.gov (United States)

    Choi, David Sanghun; Showman, Adam P.; Vasavada, Ashwin R.; Simon-Miller, Amy A.

    2013-01-01

    We present an updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes. Hot spots are relatively cloud-free regions that emit strongly at 5 lm; improved knowledge of these features is crucial for fully understanding Galileo probe measurements taken during its descent through one. Hot spots are quasistable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-like 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. These clouds travel at 150-200 m/s, much faster than the 100 m/s hot spot and plume drift speed. This raises the possibility that the scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. Most previously published zonal wind profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby wave controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed.

  19. Waves, Plumes and Bubbles from Jupiter Comet Impacts

    Science.gov (United States)

    Palotai, Csaba J.; Sankar, Ramanakumar; McCabe, Tyler; Korycansky, Donald

    2017-10-01

    We present results from our numerical simulations of jovian comet impacts that investigate various phases of the Shoemaker-Levy 9 (SL9) and the 2009 impacts into Jupiter's atmosphere. Our work includes a linked series of observationally constrained, three-dimensional radiative-hydrodynamic simulations to model the impact, plume blowout, plume flight/splash, and wave-propagation phases of those impact events. Studying these stages using a single model is challenging because the spatial and temporal scales and the temperature range of those phases may differ by orders of magnitudes (Harrington et al. 2004). In our simulations we model subsequent phases starting with the interpolation of the results of previous simulations onto a new, larger grid that is optimized for capturing all key physics of the relevant phenomena while maintaining computational efficiency. This enables us to carry out end-to-end simulations that require no ad-hoc initial conditions. In this work, we focus on the waves generated by various phenomena during the impact event and study the temporal evolution of their position and speed. In particular, we investigate the shocks generated by the impactor during atmospheric entry, the expansion of the ejected plume and the ascent of the hot bubble of material from terminal depth. These results are compared to the observed characteristics of the expanding SL9 rings (Hammel et al. 1995). Additionally, we present results from our sensitivity tests that focus on studying the differences in the ejecta plume generation using various impactor parameters (e.g., impact angle, impactor size, material, etc.). These simulations are used to explain various phenomena related to the SL9 event and to constrain the characteristics of the unknown 2009 impactor body. This research was supported by National Science Foundation Grant AST-1627409.

  20. IR sensor design insight from missile-plume prediction models

    Science.gov (United States)

    Rapanotti, John L.; Gilbert, Bruno; Richer, Guy; Stowe, Robert

    2002-08-01

    Modern anti-tank missiles and the requirement of rapid deployment have significantly reduced the use of passive armour in protecting land vehicles. Vehicle survivability is becoming more dependent on sensors, computers and countermeasures to detect and avoid threats. An analysis of missile propellants suggests that missile detection based on plume characteristics alone may be more difficult than anticipated. Currently, the passive detection of missiles depends on signatures with a significant ultraviolet component. This approach is effective in detecting anti-aircraft missiles that rely on powerful motors to pursue high-speed aircraft. The high temperature exhaust from these missiles contains significant levels of carbon dioxide, water and, often, metal oxides such as alumina. The plumes emits strongest in the infrared, 1 to 5micrometers , regions with a significant component of the signature extending into the ultraviolet domain. Many anti-tank missiles do not need the same level of propulsion and radiate significantly less. These low velocity missiles, relying on the destructive force of shaped-charge warhead, are more difficult to detect. There is virtually no ultraviolet component and detection based on UV sensors is impractical. The transition in missile detection from UV to IR is reasonable, based on trends in imaging technology, but from the analysis presented in this paper even IR imagers may have difficulty in detecting missile plumes. This suggests that the emphasis should be placed in the detection of the missile hard body in the longer wavelengths of 8 to 12micrometers . The analysis described in this paper is based on solution of the governing equations of plume physics and chemistry. These models will be used to develop better sensors and threat detection algorithms.

  1. Statistical analyses of plume composition and deposited radionuclide mixture ratios

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Terrence D.; Sallaberry, Cedric Jean-Marie; Eckert-Gallup, Aubrey Celia; Brito, Roxanne; Hunt, Brian D.; Osborn, Douglas.

    2014-01-01

    A proposed method is considered to classify the regions in the close neighborhood of selected measurements according to the ratio of two radionuclides measured from either a radioactive plume or a deposited radionuclide mixture. The subsequent associated locations are then considered in the area of interest with a representative ratio class. This method allows for a more comprehensive and meaningful understanding of the data sampled following a radiological incident.

  2. Lithological structure of the Galápagos Plume

    Science.gov (United States)

    Vidito, Christopher; Herzberg, Claude; Gazel, Esteban; Geist, Dennis; Harpp, Karen

    2013-10-01

    We have measured Ni, Ca, and Mn in olivine phenocrysts from volcanoes in the Galápagos Archipelago to infer the mantle source lithologies. Results show that peridotite is the dominant source lithology for Fernandina, Floreana, Genovesa, Wolf Island, and Darwin Island. These volcanoes largely characterize the PLUME, WD, FLO, and DUM Nd, Sr, and Pb isotopic endmembers of Harpp and White (2001). Volcan Wolf, Alcedo, Marchena, and Cerro Azul, also produced from the melting of peridotite sources, have isotopic compositions that can be defined by mixing of the four isotopic endmembers. Our analysis suggests that peridotite was present in the sources of the volcanoes covered in this study and therefore is the dominant source lithology of the Galápagos plume. Pyroxenite melting is generally focused in two isotopically distinct domains: Roca Redonda, Volcan Ecuador, and Sierra Negra in the enriched western part of the archipelago and Santiago, Santa Cruz, and Santa Fe in the depleted east. One implication of this finding is that the Western and Eastern Pyroxenite Domains represent two separate bodies of recycled crust within the Galápagos mantle plume. Furthermore, both isotopically enriched and depleted domains of the archipelago were generated from mixtures of peridotite and pyroxenite. This suggests that there is no relationship between the source lithology of the Galápagos plume and its isotopic characteristics. The identification of peridotite-source melting in volcanoes with isotopic characteristics that have been attributed to recycled crust points to the importance of mixing in OIB genesis, consistent with studies in the Canary Islands.

  3. Modeling Plume-Triggered, Melt-Enabled Lithospheric Delamination

    Science.gov (United States)

    Perry-Houts, J.; Humphreys, G.

    2015-12-01

    It has been suggested that arrival of the Yellowstone plume below North America triggered a lithospheric foundering event which aided the eruption of the Columbia River flood basalts. This hypothesis potentially accounts for some of the biggest mysteries related to the CRB's including their location as "off-track" plume volcanism; and the anomalous chemical signatures of the most voluminous units. The foundered lithosphere appears to be a remnant chunk of Farallon slab, which had been stranded beneath the Blue Mountains terrain since the accretion of Siletzia. If this is the case then the mechanisms by which this slab stayed metastable between Siletzia accretion and CRB time, and then so suddenly broke loose, is unclear. The addition of heat and mantle buoyancy supplied by the Yellowstone plume provides a clue, but the geodynamic process by which the slab was able to detach remains unclear.Efforts to model numerically the underlying processes behind delamination events have been gaining popularity. Typically, such models have relied on drastically weakened regions within the crust, or highly non-linear rheologies to enable initiation and propagation of lithosphere removal. Rather than impose such a weak region a priori, we investigated the role of mantle and crustal melt, generated by the addition of plume heat, as the source of such a rheologic boundary.We track melt generation and migration though geodynamic models using the Eulerian finite element code, ASPECT. Melt moves relative to the permeable, compacting, and viscously-deforming mantle using the approach of (Keller, et al. 2013) with the notable exception that ASPECT currently cannot model elasticity. Dike and sill emplacement is therefore still a work in progress. This work is still in the preliminary stages and results are yet inconclusive.

  4. Sediment plume monitoring in the Clarion-Clipperton Zone

    OpenAIRE

    Van den Eynde, D.; Baeye, M.; Fettweis, M.; Francken, F.; Naudts, L.; Van Lancker, V.

    2014-01-01

    OD Nature has a vast experience in monitoring and modelling Suspended Particulate Matter concentration in shelf areas. In the framework of the JPI-Oceans cruise with the RV Sonne in the Belgian, French and German concession zones for deep-sea mining in the Clarion-Clipperton Zone, this experience will be used to monitor sediments plumes, caused by deep-sea mning exploration activities.

  5. Tracing the Hawaiian Mantle Plume by Converted Seismic Waves

    OpenAIRE

    Xiaohui Yuan; Xueqing Li; I. Wölbern; Rainer Kind

    2007-01-01

    Hotspots and seamount chains belong to the fundamental components of the global plate tectonics. The Hawaii-Emperor seamount chain is believed to have been created when the oceanic lithosphere continuously passed over a stationary mantle plume located under the Hawaiian Islands. Hot buoyant material rises from great depth within a fixed narrow stern to the surface, penetrating the moving lithosphere and creating the volcanic seamounts and islands. We use teleseismic converted waves to look at...

  6. In-Situ Detection of Contaminant Plumes in Ground Water

    Science.gov (United States)

    1990-08-01

    of Engineers Cold Regions Research & Engineering Laboratory In-Situ Detection of Contaminant Plumes in Ground Water W. Rudott Setz August 1990 U S APMY...immunochemnical methodis for system (Inmanect al. 1989). Another attractiv : approach tetryl. benizene. dieldrin and paria-chloroptienylm.-th- is to us. a...not been any further work on cyanide. censt complexes. Of the important metal mo conuamni- The Office of Naval Research has recently made the nairts

  7. Modelling the fate of the Tijuana River discharge plume

    Science.gov (United States)

    van Ormondt, M.; Terrill, E.; Hibler, L. F.; van Dongeren, A. R.

    2010-12-01

    After rainfall events, the Tijuana River discharges excess runoff into the ocean in a highly turbid plume. The runoff waters contain large suspended solids concentrations, as well as high levels of toxic contaminants, bacteria, and hepatitis and enteroviruses. Public health hazards posed by the effluent often result in beach closures for several kilometers northward along the U.S. shoreline. A Delft3D model has been set up to predict the fate of the Tijuana River plume. The model takes into account the effects of tides, wind, waves, salinity, and temperature stratification. Heat exchange with the atmosphere is also included. The model consists of a relatively coarse outer domain and a high-resolution surf zone domain that are coupled with Domain Decomposition. The offshore boundary conditions are obtained from the larger NCOM SoCal model (operated by the US Navy) that spans the entire Southern California Bight. A number of discharge events are investigated, in which model results are validated against a wide range of field measurements in the San Diego Bight. These include HF Radar surface currents, REMUS tracks, drifter deployments, satellite imagery, as well as current and temperature profile measurements at a number of locations. The model is able to reproduce the observed current and temperature patterns reasonably well. Under calm conditions, the model results suggest that the hydrodynamics in the San Diego Bight are largely governed by internal waves. During rainfall events, which are typically accompanied by strong winds and high waves, wind and wave driven currents become dominant. An analysis will be made of what conditions determine the trapping and mixing of the plume inside the surfzone and/or the propagation of the plume through the breakers and onto the coastal shelf. The model is now also running in operational mode. Three day forecasts are made every 24 hours. This study was funded by the Office of Naval Research.

  8. Modeling diffusion of an alkaline plume in a clay barrier

    OpenAIRE

    Gaucher, Eric C.; Blanc, Philippe; Matray, Jean-Michel; Michau, Nicolas

    2004-01-01

    International audience; The design of clay plugs used for sealing access galleries to a radioactive waste repository built with concrete structures in a deep clayey formation must take into consideration their chemical evolution over time. Diffusion of an alkaline plume from concrete into bentonite was therefore modeled over a 100 ka period with the PHREEQC geochemical code in order to determine, as a function of time, modifications to mineral surfaces, dissolution of existing minerals and pr...

  9. Unveiling CO2 heterogeneous freezing plumes during champagne cork popping

    OpenAIRE

    Liger-Belair, G?rard; Cordier, Daniel; Honvault, Jacques; Cilindre, Clara

    2017-01-01

    Cork popping from clear transparent bottles of champagne stored at different temperatures (namely, 6, 12, and 20??C) was filmed through high-speed video imaging in the visible light spectrum. During the cork popping process, a plume mainly composed of gaseous CO2 with traces of water vapour freely expands out of the bottleneck through ambient air. Most interestingly, for the bottles stored at 20??C, the characteristic grey-white cloud of fog classically observed above the bottlenecks of champ...

  10. Bioremediation of a Large Chlorinated Solvent Plume, Dover AFB, DE

    Energy Technology Data Exchange (ETDEWEB)

    Bloom, Aleisa C [ORNL

    2015-01-01

    Bioremediation of a Large Chlorinated Solvent Plume, Dover AFB, DE Aleisa Bloom, (Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA) Robert Lyon (bob.lyon@aecom.com), Laurie Stenberg, and Holly Brown (AECOM, Germantown, Maryland, USA) ABSTRACT: Past disposal practices at Dover Air Force Base (AFB), Delaware, created a large solvent plume called Area 6 (about 1 mile long, 2,000 feet wide, and 345 acres). The main contaminants are PCE, TCE, and their degradation products. The remedy is in-situ accelerated anaerobic bioremediation (AAB). AAB started in 2006 and is focusing on source areas and downgradient plume cores. Direct-push injections occurred in source areas where contamination is typically between 5 and 20 feet below ground surface. Lower concentration dissolved-phased contamination is present downgradient at 35 and 50 feet below ground surface. Here, permanent injection/extraction wells installed in transects perpendicular to the flow of groundwater are used to apply AAB. The AAB substrate is a mix of sodium lactate, emulsified vegetable oil, and nutrients. After eight years, dissolved contaminant mass within the main 80-acre treatment area has been reduced by over 98 percent. This successful application of AAB has stopped the flux of contaminants to the more distal portions of the plume. While more time is needed for effects to be seen in the distal plume, AAB injections will soon cease, and the remedy will transition to natural attenuation. INTRODUCTION Oak Ridge National Laboratory Environmental Science Division (ORNL) and AECOM (formerly URS Corporation) have successfully implemented in situ accelerated anaerobic bioremediation (AAB) to remediate chlorinated solvent contamination in a large, multi-sourced groundwater plume at Dover Air Force Base (AFB). AAB has resulted in significant reductions of dissolved phase chlorinated solvent concentrations. This plume, called Area 6, was originally over 1 mile in length and over 2,000 feet wide (Figure 1

  11. Similarity scaling of surface-released smoke plumes

    DEFF Research Database (Denmark)

    Mikkelsen, T.; Ejsing Jørgensen, Hans; Nielsen, M.

    2002-01-01

    Concentration fluctuation data from surface-layer released smoke plumes have been investigated with the purpose of finding suitable scaling parameters for the corresponding two-particle, relative diffusion process. Dispersion properties have been measured at downwind ranges between 0.1 and 1 km f......-neighbour function is found to scale with the surface-layer friction velocity, and not with the inertial subrange dissipation rate, over the range of distance-neighbour separations considered.......Concentration fluctuation data from surface-layer released smoke plumes have been investigated with the purpose of finding suitable scaling parameters for the corresponding two-particle, relative diffusion process. Dispersion properties have been measured at downwind ranges between 0.1 and 1 km...... and duration statistics. The diffusion experiments were accompanied by detailed in-situ micrometeorological mean and turbulence measurements. In this paper, a new distance-neighbour function for surface-released smoke plumes is proposed, accompanied by experimental evidence in its support. The new distance...

  12. Martian Atmospheric Methane Plumes from Meteor Shower Infall: A Hypothesis

    Science.gov (United States)

    Fries, M.; Christou, A.; Archer, D.; Conrad, P.; Cooke, W.; Eigenbrode, J.; ten Kate, I. L.; Matney, M.; Niles, P.; Sykes, M.

    2016-01-01

    Methane plumes in the martian atmosphere have been detected using Earth-based spectroscopy, the Planetary Fourier Spectrometer on the ESA Mars Express mission, and the NASA Mars Science Laboratory. The methane's origin remains a mystery, with proposed sources including volcanism, exogenous sources like impacts and interplanetary dust, aqueous alteration of olivine in the presence of carbonaceous material, release from ancient deposits of methane clathrates, and/or biological activity. To date, none of these phenomena have been found to reliably correlate with the detection of methane plumes. An additional source exists, however: meteor showers could generate martian methane via UV pyrolysis of carbon-rich infall material. We find a correlation between the dates of Mars/cometary orbit encounters and detections of methane on Mars. We hypothesize that cometary debris falls onto Mars during these interactions, depositing freshly disaggregated meteor shower material in a regional concentration. The material generates methane via UV photolysis, resulting in a localized "plume" of short-lived methane.

  13. Detecting the Zambezi River plume using observed optical properties.

    Science.gov (United States)

    Siddorn, J R; Bowers, D G; Hoguane, A M

    2001-10-01

    In April 1998 a research cruise was carried out in the Mozambique Channel taking detailed optical, water quality and salinity measurements; the Zambezi plume waters were apparent through strong colour fronts with green waters in the plume and clear blue waters offshore. A good (r2 = 0.76) negative empirical relationship was found between the salinity (S) and yellow substance, represented by the absorption of filtered samples at 440 nm (g440). An empirical relationship was found between the salinity and a reflectance ratio: S(1/2 Zsd) = 37.45-7.07(R555/R490). An optical model in which light absorption is dominated by yellow substance and light scattering by inorganic particles confirms this empirical relationship. This has been applied to a SeaWIFS image to map salinity on the Sofala Bank, demonstrating the potential to remotely determine the distribution of the Zambezi River plume. It is thought that any significant level of chlorophyll would reduce the effectiveness of the above algorithm.

  14. Observations of nucleation of new particles in a volcanic plume.

    Science.gov (United States)

    Boulon, Julien; Sellegri, Karine; Hervo, Maxime; Laj, Paolo

    2011-07-26

    Volcanic eruptions caused major weather and climatic changes on timescales ranging from hours to centuries in the past. Volcanic particles are injected in the atmosphere both as primary particles rapidly deposited due to their large sizes on time scales of minutes to a few weeks in the troposphere, and secondary particles mainly derived from the oxidation of sulfur dioxide. These particles are responsible for the atmospheric cooling observed at both regional and global scales following large volcanic eruptions. However, large condensational sinks due to preexisting particles within the plume, and unknown nucleation mechanisms under these circumstances make the assumption of new secondary particle formation still uncertain because the phenomenon has never been observed in a volcanic plume. In this work, we report the first observation of nucleation and new secondary particle formation events in a volcanic plume. These measurements were performed at the puy de Dôme atmospheric research station in central France during the Eyjafjallajokull volcano eruption in Spring 2010. We show that the nucleation is indeed linked to exceptionally high concentrations of sulfuric acid and present an unusual high particle formation rate. In addition we demonstrate that the binary H(2)SO(4) - H(2)O nucleation scheme, as it is usually considered in modeling studies, underestimates by 7 to 8 orders of magnitude the observed particle formation rate and, therefore, should not be applied in tropospheric conditions. These results may help to revisit all past simulations of the impact of volcanic eruptions on climate.

  15. Modeling of Seismic Anisotropy Near the Hawaiian Mantle Plume

    Science.gov (United States)

    Shen, Chenghao

    Seismic anisotropy, the dependence of velocity on direction, is often induced by mantle flow. Here, I studied the influence of a proposed mantle plume beneath Hawaii on the azimuth dependence of Rayleigh wave phase velocity. I used a two-layer forward modeling code to explore how the orientation of a transversely isotropic Pyrolite mantle model controls the fast direction and strength of azimuthal anisotropy. Two layers are assumed because plate motion of the Pacific plate rearranged about 45 Million years ago. It is thought that the fossil spreading direction was 'frozen' into parts of the lithosphere while the asthenosphere below carries the signature of current mantle flow. Depending on how different the horizontal orientation of Pyrolite is in both layers, the strength of anisotropy can vanish for some frequencies but not others. This can ultimately be used to estimate the thickness of the anisotropic layers and the orientation of Pyrolite. In the second part, I forward-modeled data collected for the Hawaiian PLUME project. At high frequencies, the overall pattern of azimuthal anisotropy follows the fossil spreading direction while this coherency breaks down at low frequencies. I find that anisotropy in the upper lithosphere is largely intact, but the pattern is incoherent in the lower lithosphere and asthenosphere. These results provide strong evidence for the presence of a mantle plume beneath Hawaii.

  16. Microphysical, chemical, and dynamical processes in aircraft plumes

    Energy Technology Data Exchange (ETDEWEB)

    Kaercher, B. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere]|[Muenchen Univ., Freising (Germany). Lehrstuhl fuer Bioklimatologie und Immissionsforschung; Hirschberg, M.; Fabian, P. [Muenchen Univ., Freising (Germany). Lehrstuhl fuer Bioklimatologie und Immissionsforschung

    1997-12-01

    This project investigated theoretically microphysical and chemical processes in aircraft exhaust plumes during the first stages of wake dispersion. A suitable computational model has been developed, describing the two-dimensional (2D) turbulent mixing of a single jet of exhaust gas from aircraft engines with the atmosphere. The model has been used to work out general features of transport and conversion of exhaust effluents. It has also been employed to study the conditions in the jet that lead to the formation of ice contrails. The model has then been extended to include a set of all relevant chemical reactions in the gas phase and to study the chemical conversion of exhaust species with regard to the specific fluid dynamical conditions of the jet regime. A trajectory box model has been developed that is driven by turbulent mixing rates from the 2D jet model, and by parameterized mixing rates at later stages of wake dispersion. Further, a microphysical module has been designed and coupled to the box model, with which detailed investigations of adsorption, binary homogeneous and heterogeneous nucleation, heteromolecular condensation and evaporation, scavenging and coagulation, and homogeneous and heterogeneous freezing in diluting aircraft exhaust plumes and contrails have been performed. The potential for heterogeneous chemical processing on/in plume and contrail aerosols has been investigated. The results have supported the analyses of in situ observations. Vice versa, model development took great advantages form the close collaborations with several experimental groups. (orig.) 144 figs., 42 tabs., 497 refs.

  17. An analysis of surgical smoke plume components, capture, and evacuation.

    Science.gov (United States)

    Schultz, Leonard

    2014-02-01

    Chronic exposure to surgical smoke can transmit viruses; lead to respiratory illness; and increase the risk of more serious conditions, including Alzheimer disease, collagen and cardiac diseases, and cancer. Despite this, surgical smoke plume capture and evacuation devices are often used sporadically or not at all, and do not necessarily reduce costs per procedure. In addition, the current choices for smoke plume capture are varied, and health care providers may make decisions about what type of method to use based on marketing materials rather than facts, leaving most clinicians and managers frustrated and cynical about supporting the effort to capture surgical smoke plume. This article presents current data and information that purchasing teams can use to help choose the best available technology for their practice patterns. It also provides analysis to help those responsible for choosing smoke evacuation systems make rational decisions in their quest to provide a clean, safe environment in the OR. Copyright © 2014 AORN, Inc. Published by Elsevier Inc. All rights reserved.

  18. Salem 98: A post-plume phase, federal participation exercise

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-01-01

    Salem 98 was the largest nuclear power plant post-plume phase exercise since the 1993 FRMAC-93 exercise at the Fort Calhoun Nuclear Power Plant in Nebraska. Salem 98 was a 3 Day exercise, held on May 5--7, 1998, involving participation by the States of New Jersey and Delaware and associated State and county agencies. Public Service Electric and Gas was the host utility and Salem County the host county. Federal participation included the Nuclear Regulatory Commission, Federal Emergency Management Agency, Department of Energy, Environmental Protection Agency, US department of Agriculture and Department of Health and Human Services. In addition, the American Nuclear Insurers participated, adding a dimension to the exercise not experienced often enough. This was a stand-alone post-plume phase exercise, which took place 2 months after the evaluated plume phase exercise held on March 3, 1998, also including participation by various Federal agencies. This exercise demonstrated the positive working relationship among utility, State, county, and Federal responders in response to a postulated major nuclear power plant emergency with significant offsite consequences.

  19. Dynamics and structure of thermo-chemical mantle plumes: Are numerical models consistent with observations?

    Science.gov (United States)

    Dannberg, J.; Sobolev, S. V.

    2013-12-01

    According to widely accepted models, plumes ascend from the core-mantle boundary and cause massive melting when they reach the base of the lithosphere. Most of these models consider plumes as purely thermal and predict flattening of the plume head to a disk-like structure, thin plume tails with a radius on the scale of 100 km and kilometer-scale topographic uplift before and during the eruption of flood basalts. However, several paleogeographic and paleotectonic field studies indicate significantly smaller surface uplift during the development of many LIPs, and seismic imaging reveals thicker plume tails as well as a more complex plume structure in the upper mantle including broad low-velocity anomalies up to 400 km depth and elongated low-velocity fingers. Moreover, geochemical data indicate a plume composition that differs from that of the average mantle and recent geodynamic models of plumes in the upper mantle show that plumes containing a large fraction of eclogite and therefore having very low buoyancy can explain the observations much better. Nevertheless, the question remains how such a low-buoyancy plume can rise through the whole mantle and how this ascent affects its dynamics. We perform numerical experiments in 2D axisymmetric geometry to systematically study the dynamics of the plume ascent as well as 2D and 3D models with prescribed velocity at the upper boundary to investigate the interaction between plume- and plate-driven flow. For that purpose, we use modified versions of the finite-element codes Citcom and Aspect. Our models employ complex material properties incorporating phase transitions with the accompanying density changes, Clapeyron slopes and latent heat effects for the peridotite and eclogite phase, mantle compressibility and a highly temperature- and depth-dependent viscosity. We study under which conditions (excess temperature, plume volume and eclogite content) thermo-chemical plumes can ascend through the whole mantle and what

  20. Laboratory experiments on two coalescing axisymmetric turbulent plumes in a rotating fluid

    Science.gov (United States)

    Yamamoto, H.; Cenedese, C.; Caulfield, C. P.

    2011-05-01

    We investigate the early-time coalescence of two co-flowing axisymmetric turbulent plumes and the later-time flow of the induced vortices in a rotating, homogeneous fluid using laboratory experiments. The experiments demonstrate the critical importance of the rotation period Tf=2π /f, where f is the Coriolis parameter of the background rotation. We find that if the plumes' sources are sufficiently "close" for the plumes to merge initially at an "early time" tm≲tr=3Tf/4, the experimentally observed merging height zme agrees well with the non-rotating theoretical relationship of zmt≈(0.44/α)x0plumes, x0 is the separation distance between the two plume sources, F0 is the source buoyancy flux of each plume, and zr is the distance that the plume rises in the time tr before rotational effects become significant. Therefore, rotation does not affect the initial time to merger or the initial merger height of such "close" plumes. For "late" times t >tr, however, the flow dynamics are substantially more complicated, as the flow becomes significantly affected by rotation. The propagation and entrainment of the plumes becomes strongly affected by the vortices induced by the entrainment flow in a rotating environment. Also, the plume fluid itself starts to interact with these vortices. If the plumes have already initially merged by the time t =tr, a single vortex (initially located at the midpoint of the line connecting the two plume sources) develops, which both advects and modifies the geometry of the merging plumes. Coupled with the various suppressing effects of rotation on the radial plume entrainment, the "apparent" observed height of merger can vary substantially from its initial value. Conversely, for more widely separated "distant" plumes, where x0>xc=(25α /2)F01/4f-3/4, the plumes do not merge before the critical time tr when rotation becomes significant in the flow dynamics and two vortices are observed, each located over a plume source. The combined effect of

  1. Modeling Smoke Plume-Rise and Dispersion from Southern United States Prescribed Burns with Daysmoke

    Directory of Open Access Journals (Sweden)

    Mehmet Talat Odman

    2011-08-01

    Full Text Available We present Daysmoke, an empirical-statistical plume rise and dispersion model for simulating smoke from prescribed burns. Prescribed fires are characterized by complex plume structure including multiple-core updrafts which makes modeling with simple plume models difficult. Daysmoke accounts for plume structure in a three-dimensional veering/sheering atmospheric environment, multiple-core updrafts, and detrainment of particulate matter. The number of empirical coefficients appearing in the model theory is reduced through a sensitivity analysis with the Fourier Amplitude Sensitivity Test (FAST. Daysmoke simulations for “bent-over” plumes compare closely with Briggs theory although the two-thirds law is not explicit in Daysmoke. However, the solutions for the “highly-tilted” plume characterized by weak buoyancy, low initial vertical velocity, and large initial plume diameter depart considerably from Briggs theory. Results from a study of weak plumes from prescribed burns at Fort Benning GA showed simulated ground-level PM2.5 comparing favorably with observations taken within the first eight kilometers of eleven prescribed burns. Daysmoke placed plume tops near the lower end of the range of observed plume tops for six prescribed burns. Daysmoke provides the levels and amounts of smoke injected into regional scale air quality models. Results from CMAQ with and without an adaptive grid are presented.

  2. Three-dimensional laboratory modeling of the Tonga trench and Samoan plume interaction

    Science.gov (United States)

    Druken, K. A.; Kincaid, C. R.; Pockalny, R. A.; Griffiths, R. W.; Hart, S. R.

    2009-12-01

    Plume processes occurring near ridge centers (e.g. Iceland) or mid-plate (e.g. Hawaii) have been well studied; however, the behavior of a plume near a subducting plate is still poorly understood and may in fact differ from the typical expected plume surfacing patterns. We investigate how three-dimensional subduction-driven flow relates to the deformation and dispersal of nearby upwelling plume material and the associated geochemical spatial patterns, with site-specific comparisons to the Tonga trench and Samoan plume system. Eighteen plume-trench laboratory experiments were conducted with varied combinations of subduction motions (down-dip, trench rollback, slab steepening and back-arc extension) and plume parameters (position and temperature.) A phenolic plate and glucose syrup, with a temperature dependent viscosity, are used to model the slab and upper mantle, respectively. Hydraulic pistons control longitudinal, translational and steepening motions of the slab as a simplified kinematic approach to mimic dynamic experiments. Results show that the subduction-induced flow dominates the upwelling strength of the plume, causing a significant portion of the plume head to subduct before reaching the melt zone. The remaining material is entrained around the slab edge into the mantle wedge by the trench rollback-induced flow. The proportion of subducted verses entrained material is predominantly dependent on plume location (relative to the trench) and thermal strength, with additional effects from back-arc extension and plate steepening.

  3. The time varying structure of a river plume: Observations with an autonomous glider.

    Science.gov (United States)

    Chant, R. J.; Glenn, S. M.; Gong, D.

    2004-12-01

    During the 2004 LaTTE (Lagrangian Transport and Transformation Experiment) pilot study we deployed a Slocum Autonomous glider on a 10-day mission to run repeated transects across the Hudson River Plume in the vicinity of Sandy Hook. The glider completed 13 cross-plume surveys during the mission with horizontal resolution of approximately 100 meters. Wind forcing was highly variable and fluctuated between upwelling and downwelling conditions at 1-2 day intervals. Tidal forcing decreased markedly from spring to neap tide conditions and river discharge averaged approximately 500 m3/s during the survey. The plume responded rapidly to the variable wind forcing. During upwelling conditions the plume thinned and extended over 30 km from shore, while during downwelling winds the plume thickened and was compressed at the shore. However, during both upwellling and downwelling conditions the plume remained detached from the bottom. The cross-sectional area of the plume also tended to vary with the wind forcing. However, a significant increase in the plume's area during the last half of the mission does not appear to be related to either wind forcing or river discharge. Instead, we suggest that the plumes structure could be impacted by spring neap variability which is known to control stratification and freshwater fluxes out of the Hudson River Estuary. This presentation will relate the structure of the plume to wind forcing, river flow and the spring/neap cycle.

  4. Lithospheric topography, tilted plumes, and the track of the Snake River-Yellowstone hot spot

    Science.gov (United States)

    Shervais, John W.; Hanan, Barry B.

    2008-10-01

    The trace of the Snake River-Yellowstone hot spot is the world's best example of a mantle plume that has been overridden by continental lithosphere. The "standard model" calls for the plume head to rise under northern Nevada and be forced northward to form basalts of the Columbia Plateau; subsequent movement of North America to the southwest over the plume tail created a hot spot trace on the surface. We present a new conceptual model for the origin of this feature that resolves inconsistencies in the current standard model and explains the recent documentation of a thermal anomaly in the mantle below Yellowstone today that plunges ˜65° WNW. Our model implies that the plume tail was forced beneath thinned cratonic lithosphere to the SE along with part of the plume head and has remained in this orientation for the last 12 Ma. We infer that almost all of the volcanism in SE Oregon and SW Idaho prior to 12 Ma results from overriding the southern extension of the plume head, not the plume tail, and that a distinct plume tail hot spot track was not established until formation of the Bruneau-Jarbidge eruptive center around 12 Ma. The plume tail track may also be controlled by a preexisting structural boundary in lithosphere that is thinner than adjacent lithosphere. This model demonstrates the potential importance of lithospheric topography on controlling the surface manifestation of plume volcanism and the complexity that may arise when lithospheric thickness is nonuniform.

  5. Coastal pollution hazards in southern California observed by SAR imagery: stormwater plumes, wastewater plumes, and natural hydrocarbon seeps

    Science.gov (United States)

    Digiacomo, Paul M.; Washburn, Libe; Holt, Benjamin; Jones, Burton H.

    2004-01-01

    Stormwater runoff plumes, municipal wastewater plumes, and natural hydrocarbon seeps are important pollution hazards for the heavily populated Southern California Bight (SCB). Due to their small size, dynamic and episodic nature, these hazards are difficult to sample adequately using traditional in situ oceanographic methods. Complex coastal circulation and persistent cloud cover can further complicate detection and monitoring of these hazards. We use imagery from space-borne synthetic aperture radar (SAR), complemented by field measurements, to examine these hazards in the SCB. The hazards are detectable in SAR imagery because they deposit surfactants on the sea surface, smoothing capillary and small gravity waves to produce areas of reduced backscatter compared with the surrounding ocean. We suggest that high-resolution SAR, which obtains useful data regardless of darkness or cloud cover, could be an important observational tool for assessment and monitoring of coastal marine pollution hazards in the SCB and other urbanized coastal regions.

  6. Vapor plume oscillation mechanisms in transient keyhole during tandem dual beam fiber laser welding

    Science.gov (United States)

    Chen, Xin; Zhang, Xiaosi; Pang, Shengyong; Hu, Renzhi; Xiao, Jianzhong

    2018-01-01

    Vapor plume oscillations are common physical phenomena that have an important influence on the welding process in dual beam laser welding. However, until now, the oscillation mechanisms of vapor plumes remain unclear. This is primarily because mesoscale vapor plume dynamics inside a millimeter-scale, invisible, and time-dependent keyhole are difficult to quantitatively observe. In this paper, based on a developed three-dimensional (3D) comprehensive model, the vapor plume evolutions in a dynamical keyhole are directly simulated in tandem dual beam, short-wavelength laser welding. Combined with the vapor plume behaviors outside the keyhole observed by high-speed imaging, the vapor plume oscillations in dynamical keyholes at different inter-beam distances are the first, to our knowledge, to be quantitatively analyzed. It is found that vapor plume oscillations outside the keyhole mainly result from vapor plume instabilities inside the keyhole. The ejection velocity at the keyhole opening and dynamical behaviors outside the keyhole of a vapor plume both violently oscillate with the same order of magnitude of high frequency (several kHz). Furthermore, the ejection speed at the keyhole opening and ejection area outside the keyhole both decrease as the beam distance increases, while the degree of vapor plume instability first decreases and then increases with increasing beam distance from 0.6 to 1.0 mm. Moreover, the oscillation mechanisms of a vapor plume inside the dynamical keyhole irradiated by dual laser beams are investigated by thoroughly analyzing the vapor plume occurrence and flow process. The vapor plume oscillations in the dynamical keyhole are found to mainly result from violent local evaporations and severe keyhole geometry variations. In short, the quantitative method and these findings can serve as a reference for further understanding of the physical mechanisms in dual beam laser welding and of processing optimizations in industrial applications.

  7. The effect of recycled oceanic crust in the thermal evolution of the Galapagos Plume

    Science.gov (United States)

    Gazel, E.; Herzberg, C. T.; Vidito, C. A.

    2011-12-01

    Current models suggest that the massive basaltic production responsible for the emplacement of Large Igneous Provinces (LIPS) during the Permian-Paleocene may represent the initial phases (plume heads) of some of the mantle plumes that feed the current ocean island basalts (OIB). In many cases, magmatism associated with the initiation of mantle plumes was so voluminous that produced global environmental impacts. The origin of these intra-plate magmatism is still debated but recent petrological, geochemical and geophysical studies of some of these localities like Samoa, Hawaii, Galapagos, provide evidence that melting is related to a true mantle plume, representing a geochemically heterogeneous, hot-buoyant domain that originates from a boundary layer beneath the upper mantle. Thus, plume-related magmas produced in OIB and LIPS and their connecting plume tracks are windows into the Earth's mantle, providing evidence on mantle temperature, size and composition of heterogeneities, and the deep earth geochemical cycles. Our preliminary petrological modeling suggests that mantle plumes for LIPS with Permian-Paleocene ages were generally hotter and melted more extensively than plumes of more modern oceanic islands. Although a lot of work has been done on LIPS and OIB, no complete record of the evolution of a mantle plume is available to this point, mostly due to the inaccessibility of the submerged sections of almost all plume tracks. Galapagos-related lavas provide a complete record of the evolution of a mantle plume since the plume's initial stages in the Cretaceous. In the case of the Galapagos, our work suggests a decrease from TP(max) of1650 C in the Cretaceous to 1500 C in the present day. Our recent work on the Galapagos Islands and the preliminary work on older Galapagos-related terranes suggest that this secular cooling is directly related with increasing amounts of recycled crust in the plume.

  8. Ozone production efficiency of a ship-plume: ITCT 2K2 case study.

    Science.gov (United States)

    Kim, Hyun S; Kim, Yong H; Han, Kyung M; Kim, Jhoon; Song, Chul H

    2016-01-01

    Ozone production efficiency (OPE) of ship plume was first evaluated in this study, based on ship-plume photochemical/dynamic model simulations and the ship-plume composition data measured during the ITCT 2K2 (Intercontinental Transport and Chemical Transformation 2002) aircraft campaign. The averaged instantaneous OPEs (OPE(i)‾) estimated via the ship-plume photochemical/dynamic modeling for the ITCT 2K2 ship-plume ranged between 4.61 and 18.92, showing that the values vary with the extent of chemical evolution (or chemical stage) of the ship plume and the stability classes of the marine boundary layer (MBL). Together with OPE(i)‾, the equivalent OPEs (OPE(e)‾) for the entire ITCT 2K2 ship-plume were also estimated. The OPE(e)‾ values varied between 9.73 (for the stable MBL) and 12.73 (for the moderately stable MBL), which agreed well with the OPE(e)‾ of 12.85 estimated based on the ITCT 2K2 ship-plume observations. It was also found that both the model-simulated and observation-based OPE(e)‾ inside the ship-plume were 0.29-0.38 times smaller than the OPE(e)‾ calculated/measured outside the ITCT 2K2 ship-plume. Such low OPEs insides the ship plume were due to the high levels of NO and non-liner ship-plume photochemistry. Possible implications of this ship-plume OPE study in the global chemistry-transport modeling are also discussed. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  9. Development of a point plume in the presence of background rotation

    Science.gov (United States)

    Fernando, H. J. S.; Chen, R.-r.; Ayotte, B. A.

    1998-09-01

    This paper describes a laboratory study on the evolution of a point turbulent plume placed at the free surface of a homogeneous fluid layer in the presence of background rotation. It is shown that the plume initially evolves as if there is no rotation. However, the rotational effects become important after the plume descends a vertical distance hc1≈3.3(B/Ω3)1/4 for a normalized time Ωtc1≈2.4, whence the vertical descent rate of the plume is reduced while maintaining approximately the same lateral growth rate. Here Ω is the rate of background rotation and B is the specific buoyancy flux of the plume. The rotational effects inhibit the lateral growth of the plume at a time Ωtc2≈5.5, when the maximum plume width is bc≈1.4(B/Ω3)1/4. Thereafter, the vertical descent continues and the plume evolves into a cylindrical shape while developing a cyclonic circulation in and around it, except near the plume front. Upon reaching the bottom surface after traveling a fluid depth of H, the plume deflects, propagates horizontally, and becomes unstable breaking up into anticyclonic eddies. Studies carried out for the case of Hinitiated at a horizontal length scale proportional to the Rossby deformation radius of the deflected flow, and hence it is of baroclinic type. These eddies appear to align vertically with the cyclonic eddies formed by the barotropic instability of the surface rim current, thus producing heton-like structures. The influence of the diameter d0 of the plume on the flow evolution is also studied, and it is shown that plumes with aspect ratio h/d0<12 (where h is the vertical extent) can be approximated as point plumes. Scaling arguments are advanced to explain the results. Some geophysical applications of the study are also discussed.

  10. Multifrequency radar imaging of ash plumes: an experiment at Stromboli

    Science.gov (United States)

    Donnadieu, Franck; Freret-Lorgeril, Valentin; Delanoë, Julien; Vinson, Jean-Paul; Peyrin, Frédéric; Hervier, Claude; Caudoux, Christophe; Van Baelen, Joël; Latchimy, Thierry

    2016-04-01

    Volcanic ash emissions in the atmosphere are hazardous to aviation while ash fallout affects people and human activities and may cause damage to infrastructures and economic losses. In the framework of the French Government Laboratory of Excellence ClerVolc initiative, an experiment was carried out on Stromboli volcano (Italy), between 28 September and 4 October 2015. The aim was to retrieve various physical properties of the ash plumes, especially the mass loading parameters which are critical for the modelling of ash dispersal. We used a complementary set of cutting edge techniques recording in different bands of the electromagnetic spectrum. The innovative instrument setup consisted in three radars, hyperspectral thermal infrared and dual-band UV cameras, a mini DOAS-Flyspec and a multigas sensor. A drone equipped with differential GPS was flown near the ash plumes with several sensors including SO2, CO2 and particle counter. We mainly focus on radar measurements of over 200 ash plumes and present some preliminary comparisons at three frequencies. The BASTA Doppler radar at 95 GHz, originally designed for atmospheric studies, was deployed at about 2.2 km in slant distance from the eruptive craters. It was configured to observe volumes above one of the active craters with a spatio-temporal resolution of 12.5 m and 1 s. From the same location, a 1.2 GHz volcano Doppler radar (VOLDORAD) was recording the signature of ballistics and small lapilli at 0.15 s in 60 m-deep volumes. In addition, a commercial 24 GHz micro rain Doppler radar (MRR) simultaneously recorded activity from the Rochette station, at 400 to 650 m from the active craters with a sampling rate of 10 s and a resolution of 25 m. The latter was pointing almost perpendicularly to the other radar beams. Reflectivity factors were measured inside the ash plume above the source vent by the BASTA radar (3 mm wavelength) spanning -9 to +21 dBZ. Fallout could sometimes be tracked during several minutes within

  11. On the Color of the Orinoco River Plume

    Science.gov (United States)

    Odriozola, A.; Muller-Karger, F.; Carder, K.; Hu, C.; Varela, R.

    2005-05-01

    In situ measurements were used to study the bio-optical properties of marine waters within the Gulf of Paria (GOP, Venezuela) and in the Southeastern Caribbean Sea (SEC) as they are affected by the seasonal discharge of the Orinoco River plume. The main purpose of this study was to determine the impact of colored dissolved organic matter (CDOM) (also known as Gelbstoff), phytoplankton, and total suspended matter (TSM) in the color of the Orinoco River plume. This information is essential for regional ocean color algorithms development. Salinity and silica values indicate that the GOP and SEC waters were under the influence of the Orinoco River plume during both seasons. This riverine influence resulted in high values of Gelbstoff absorption, ag(λ), which contributed to up to 90% of the total absorption at 440 nm in both the GOP and SEC regardless of the season. Phytoplankton absorption contributions were normally around 5%, but during the dry season these values reached 20% in the SEC. Ratios of ag(440) to ph(440) were extremely large, with most of the values ranging from 10 to 50. Due to the strong absorption by Gelbstoff, light at the blue wavelengths (412 nm, 440 nm and 490 nm) was attenuated to 1% of the subsurface irradiance in the first 5 m of the water column within the GOP, and in the first 10 m of the water column in the SEC. Furthermore, the absorption by Gelbstoff significantly decreased the water leaving radiance (Lw(λ)) in the blue wavelengths along the Orinoco River plume. As ag(λ) relatively decreased from the GOP to the SEC (mean ~1.6 m-1 and mean ~0.9 m-1, respectively), a shift in the maximum peak of Rrs(λ) spectra (Rrsmax(λ)), towards shorter wavelengths (from ~ 580 nm to ~500 nm) was observed. Similar to Gelbstoff, concentrations of TSM normally decreased from the stations near the Delta to the stations in the SEC. The impact of TSM on the color of the Orinoco plume was represented by a reduction in the magnitude of Rrsmax(λ) of ~50% going

  12. Enceladus Plume Morphology and Variability from UVIS Measurements

    Science.gov (United States)

    Hansen, Candice; Esposito, Larry; Colwell, Josh; Hendrix, Amanda; Portyankina, Ganna

    2017-10-01

    The Ultraviolet Imaging Spectrograph (UVIS) on the Cassini spacecraft has been observing Enceladus’ plume and its effect on the Saturnian environment since 2004. One solar and 7 stellar occultations have been observed between 2005 and 2017. On 27 March 2017 epsilon Canis Majoris (CMa) passed behind the plume of water vapor spewing from Enceladus’ tiger stripe fissures. With this occultation we have 6 cuts through the plume at a variety of orientations over 12 years. Following our standard procedure the column density along the line of sight from Enceladus to the star was determined and the water flux calculated [1]. The mean anomaly was 131, well away from the dust flux peak associated with Enceladus at an orbital longitude near apoapsis [2]. We find that the water vapor flux was ~160 kg/sec (this number will be refined when the final reconstructed trajectory is available). That puts it “in family” with the other occultations, with values that cluster around 200 kg/sec. It is at the low end, which may be consistent with the drop in particle output observed over the last decade [3]. UVIS results show that the supersonic collimated gas jets imbedded in the plume are the likely source of the variability in dust output [4], rather than overall flux from the tiger stripes. An occultation of epsilon Orionis was observed on 11 March 2016 when Enceladus was at a mean anomaly of 208. Although the bulk flux changed little the amount of water vapor coming from the Baghdad I supersonic jet increased by 25% relative to 2011. The Baghdad I jet was observed again in the 2017 epsilon CMa occultation, and the column density is half that of 2016, further bolstering the conclusion that the gas jets change output as a function of orbital longitude. UVIS results describing gas flux, jets, and general structure of the plume, the observables above the surface, are key to testing hypotheses for what is driving Enceladus’ eruptive activity below the surface. [1] Hansen, C. J. et

  13. Secondary organic aerosol formation in biomass-burning plumes: Theoretical analysis of lab studies and ambient plumes

    OpenAIRE

    Bian, Qijing; Jathar, Shantanu H.; Kodros, John K.; Barsanti, Kelley C.; Hatch, Lindsay E.; May, Andrew A.; Kreidenweis, Sonia M.; Pierce, Jeffrey R.

    2016-01-01

    Secondary organic aerosol (SOA) has been shown to form in biomass-burning emissions in laboratory and field studies. However, there is significant variability among studies in mass enhancement, which could be due to differences in fuels, fire conditions, dilution, and/or limitations of laboratory experiments and observations. This study focuses on understanding processes affecting biomass-burning SOA formation in laboratory smog-chamber experiments and in ambient plumes. Vapor wall losses hav...

  14. Charge structure in volcanic plumes: a comparison of plume properties predicted by an integral plume model to observations of volcanic lightning during the 2010 eruption of Eyjafjallajökull, Iceland.

    Science.gov (United States)

    Woodhouse, Mark J; Behnke, Sonja A

    Observations of volcanic lightning made using a lightning mapping array during the 2010 eruption of Eyjafjallajökull allow the trajectory and growth of the volcanic plume to be determined. The lightning observations are compared with predictions of an integral model of volcanic plumes that includes descriptions of the interaction with wind and the effects of moisture. We show that the trajectory predicted by the integral model closely matches the observational data and the model well describes the growth of the plume downwind of the vent. Analysis of the lightning signals reveals information on the dominant charge structure within the volcanic plume. During the Eyjafjallajökull eruption both monopole and dipole charge structures were observed in the plume. By using the integral plume model, we propose the varying charge structure is connected to the availability of condensed water and low temperatures at high altitudes in the plume, suggesting ice formation may have contributed to the generation of a dipole charge structure via thunderstorm-style ice-based charging mechanisms, though overall this charging mechanism is believed to have had only a weak influence on the production of lightning.

  15. Distinguishing Remobilized Ash From Erupted Volcanic Plumes Using Space-Borne Multiangle Imaging

    Science.gov (United States)

    Flower, Verity J. B.; Kahn, Ralph A.

    2017-10-01

    Volcanic systems are composed of a complex combination of ongoing eruptive activity and secondary hazards, such as remobilized ash plumes. Similarities in the visual characteristics of remobilized and erupted plumes, as imaged by satellite-based remote sensing, complicate the accurate classification of these events. The stereo imaging capabilities of the Multiangle Imaging Spectroradiometer (MISR) were used to determine the altitude and distribution of suspended particles. Remobilized ash shows distinct dispersion, with particles distributed within 1.5 km of the surface. Particle transport is consistently constrained by local topography, limiting dispersion pathways downwind. The MISR Research Aerosol retrieval algorithm was used to assess plume particle microphysical properties. Remobilized ash plumes displayed a dominance of large particles with consistent absorption and angularity properties, distinct from emitted plumes. The combination of vertical distribution, topographic control, and particle microphysical properties makes it possible to distinguish remobilized ash flows from eruptive plumes, globally.

  16. Plasma Plume Characterization of the HERMeS during a 1722-hr Wear Test Campaign

    Science.gov (United States)

    Huang, Wensheng; Williams, George J.; Peterson, Peter Y.; Kamhawi, Hani; Gilland, James H.; Herman, Daniel A.

    2017-01-01

    A 1722-hour wear test campaign of NASAs 12.5 kilowatt Hall Effect Rocket with Magnetic Shielding was completed. This wear test campaign, completed in 2016, was divided into four segments including an electrical configuration characterization test, two short duration tests, and one long wear test. During the electrical configuration characterization test, the plasma plume was examined to provide data to support the down select of the electrical configuration for further testing. During the long wear tests, the plasma plume was periodically examined for indications of changes in thruster behavior. Examination of the plasma plume data from the electrical configuration characterization test revealed a correlation between the plume properties and the presence of a conduction path through the front poles. Examination of the long wear test plasma plume data revealed that the plume characteristics remained unchanged during testing to within the measurement uncertainty.

  17. The role of a mantle plume in the formation of Yellowstone volcanism

    Science.gov (United States)

    Leonard, Tiffany; Liu, Lijun

    2016-02-01

    The origin of the Yellowstone volcanic province remains debated. Proposed hypotheses involve either a mantle plume or not. Recent tomographic images allow a quantitative evaluation of the plume hypothesis and its interaction with the Farallon slabs. Using 4-D geodynamic models with data assimilation, we find that the slab is always in the way of the initially rising plume and that the plume could reach the surface only through the broken slab hinge at ~15 Ma. For most of the time, the sinking slabs dominate the mantle flow and prohibit upwelling. We find that a plume that satisfies the present mantle image beneath Yellowstone fails to predict both voluminous hot materials at shallow depths beneath the western U.S. and the age migration of the hot spot tracks. We suggest that a plume is likely to have much less influence on the Yellowstone volcanism than previously thought.

  18. Parameterization of subgrid plume dilution for use in large-scale atmospheric simulations

    Directory of Open Access Journals (Sweden)

    A. D. Naiman

    2010-03-01

    Full Text Available A new model of plume dynamics has been developed for use as a subgrid model of plume dilution in a large-scale atmospheric simulation. The model uses mean wind, shear, and diffusion parameters derived from the local large-scale variables to advance the plume cross-sectional shape and area in time. Comparisons with a large eddy simulation of aircraft emission plume dynamics, with an analytical solution to the dynamics of a sheared Gaussian plume, and with measurements of aircraft exhaust plume dilution at cruise altitude show good agreement with these previous studies. We argue that the model also provides a reasonable approximation of line-shaped contrail dilution and give an example of how it can be applied in a global climate model.

  19. Laboratory-Scale Simulation of Spiral Plumes in Fluid with Hight Ptandtl Number

    CERN Document Server

    Sharifulin, A N

    2013-01-01

    We experimentally investigated the appearance of a plumes from local hot spot and study its interaction with cellular flow in closed cavity filled by silicon oil with Prandtl number Pr ~2*10^3 . Convective plume is generated by a local heat source, located on the top of the small rubber cylinder, which is located in the center of the bottom of the rectangular cell. Green laser has been used to simulate the hot-spot. Roll-type large-scale convective flow is generated by heating of the one vertical sides of cavity. Influence of power of hot point on the shape of plume has been investigated. It is shown that the presence of cellular convective motion may lead to the formation of a strange spiral convective plume. This plume looks like Archimedes spiral replaced on vertical plane. Physical mechanism of the formation of strange spiral plume and application of obtained results for mantle convection problems are discussed.

  20. Mineral Formation and Trace Element Uptake in Rising Hydrothermal Plumes of the Lau Basin

    Science.gov (United States)

    Breier, J. A.; Osicki, O.; Jiang, H.; Anantharaman, K.; Dick, G.; Wendt, K.; Sorensen, J. V.; Toner, B.

    2011-12-01

    Hydrothermal plumes are enriched in a variety of trace elements (e.g., V, As, and the rare earths) and micronutrients (e.g., Fe, Mn, Cu, Zn, and P) that are (i) extracted from the lithosphere and (ii) scavenged from seawater. Mineral particles are the transport vector for these trace elements. The relative importance of these sources and their net effect on sedimentary and marine element cycles depends on the mechanisms of trace element sequestration within plume mineral particles, the stability of the mineral phases that sequester them, and potentially the modification of plume chemistry by microbial processes. Lau Basin vents span a range of endmember chemistries and temperatures and are thus a useful setting for investigating the relationship between plume trace element composition and mineralogy. Our investigation of the rising plume chemistry of Lau Basin vents addresses these questions by comparing particulate trace element covariations through the rising plume with measured and modeled mineral formation for samples collected from three distinct hydrothermal fields: Kilo Moana, ABE, and Mariner. These rising plume samples span the initial particle formation process through sulfide formation to initial oxide formation, in addition to spanning a range of endmember vent chemistries. The trends between trace elements and Fe are nonlinear, for several elements (e.g., P, V) this contrasts with previous findings of linear trends in the neutrally buoyant plume. These trends are explained in the context of the transition from rising plume mineral mixtures dominated by sulfides to those with an increasing oxide component, upon which geochemical differences related to inter-field variations in endmember vent chemistry are superimposed. These results indicate that the sources and mechanisms of trace element enrichment vary significantly over the plume mixing path and suggest the apparent mechanisms that control plume trace element composition in neutrally buoyant plumes

  1. Natural attenuation: A feasible approach to remediation of landfill leachate plumes?

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Kjeldsen, Peter; Bjerg, Poul Løgstrup

    2000-01-01

    Natural attenuation has been implemented for petroleum hydrocarbons plumes and recently also for chlorinated solvent plumes, primarily in the USA, but natural attenuation has not yet gained a foothold with respect to leachate plumes. Based on the experiences gained from ten years of research on two...... Danish landfills, it is suggested that natural attenuation is a feasible approach, but much more complicated and demanding than in the case of petroleum hydrocarbons and chlorinated solvent....

  2. Ship plume dispersion rates in convective boundary layers for chemistry models

    OpenAIRE

    Chosson, F.; Paoli, R.; B. Cuenot

    2008-01-01

    International audience; Detailed ship plume simulations in various convective boundary layer situations have been performed using a Lagrangian Dispersion Model driven by a Large Eddy Simulation Model. The simulations focus on early stage (1–2 h) of plume dispersion regime and take into account the effects of plume rise on dispersion. Results are presented in an attempt to provide to chemical modellers community a realistic description of the impact of characteristic dispersion on exhaust ship...

  3. Insights into the formation and dynamics of coignimbrite plumes from one-dimensional models

    Science.gov (United States)

    Engwell, S. L.; de'Michieli Vitturi, M.; Esposti Ongaro, T.; Neri, A.

    2016-06-01

    Coignimbrite plumes provide a common and effective mechanism by which large volumes of fine-grained ash are injected into the atmosphere. Nevertheless, controls on formation of these plumes as a function of eruptive conditions are still poorly constrained. Herein, two 1-D axysymmetric steady state models were coupled, the first describing the parent pyroclastic density current and the second describing plume rise. Global sensitivity analysis is applied to investigate controls on coignimbrite plume formation and describe coignimbrite source and the maximum plume height attained. For a range of initial mass flow rates between 108 and 1010 kg/s, modeled liftoff distance (the distance at which neutral buoyancy is attained), assuming radial supercritical flow, is controlled by the initial flow radius, gas mass fraction, flow thickness, and temperature. The predicted decrease in median grain size between flow initiation and plume liftoff is negligible. Calculated initial plume vertical velocities, assuming uniform liftoff velocity over the pyroclastic density current invasion area, are much greater (several tens of m/s) than those previously used in modeling coignimbrite plumes (1 m/s). Such velocities are inconsistent with the fine grain size of particles lofted into coignimbrite plumes, highlighting an unavailability of large clasts, possibly due to particle segregation within the flow, prior to plume formation. Source radius and initial vertical velocity have the largest effect on maximum plume height, closely followed by initial temperature. Modeled plume heights are between 25 and 47 km, comparable with Plinian eruption columns, highlighting the potential of such events for distributing fine-grained ash over significant areas.

  4. Impact of personal factors and furniture arrangement on the thermal plume above a sitting occupant

    DEFF Research Database (Denmark)

    Zukowska, Daria; Melikov, Arsen Krikor; Popiolek, Zbigniew

    2012-01-01

    The impact of thermal insulation and the design of clothing and chair, the blocking effect of a table and breathing on the thermal plume above a sitting thermal manikin was studied in a climate chamber. Air speed and temperature in the plume cross-section 0.7 m above the manikin head were measured...... distributions in the plume and increases volume flux by almost 50%. Exhaling through the mouth expands the plume, resulting in the integral characteristics being 40% greater and therefore should be considered in numerical simulations or experiments with thermal manikins, while exhaling through the nose can...

  5. Large-eddy simulation of bubble-driven plume in stably stratified flow.

    Science.gov (United States)

    Yang, Di; Chen, Bicheng; Socolofsky, Scott; Chamecki, Marcelo; Meneveau, Charles

    2015-11-01

    The interaction between a bubble-driven plume and stratified water column plays a vital role in many environmental and engineering applications. As the bubbles are released from a localized source, they induce a positive buoyancy flux that generates an upward plume. As the plume rises, it entrains ambient water, and when the plume rises to a higher elevation where the stratification-induced negative buoyancy is sufficient, a considerable fraction of the entrained fluid detrains, or peels, to form a downward outer plume and a lateral intrusion layer. In the case of multiphase plumes, the intrusion layer may also trap weakly buoyant particles (e.g., oil droplets in the case of a subsea accidental blowout). In this study, the complex plume dynamics is studied using large-eddy simulation (LES), with the flow field simulated by hybrid pseudospectral/finite-difference scheme, and the bubble and dye concentration fields simulated by finite-volume scheme. The spatial and temporal characteristics of the buoyant plume are studied, with a focus on the effects of different bubble buoyancy levels. The LES data provide useful mean plume statistics for evaluating the accuracy of 1-D engineering models for entrainment and peeling fluxes. Based on the insights learned from the LES, a new continuous peeling model is developed and tested. Study supported by the Gulf of Mexico Research Initiative (GoMRI).

  6. Are there signatures of active Europa plumes in Galileo in-situ data?

    Science.gov (United States)

    Huybrighs, H. L. F.; Roussos, E.; Krupp, N.; Fraenz, M.; Futaana, Y.; Barabash, S.; Glassmeier, K.-H.

    2017-09-01

    Hubble Space Telescope observations made during recent years suggest that recurring water vapour plumes originating from Europa's surface exist, though they do not conclusively prove their existence. Indisputable (in-situ) observations of these plumes have not been reported yet. However, it may be possible that the NASA Galileo mission encountered these plumes in the past. We present an overview of in-situ data obtained by the Galileo spacecraft during the Europa flybys. The data is compared in the context of the search for signs of active plumes.

  7. Plume and surface feature structure and compositional effects on Europa's global exosphere: Preliminary Europa mission predictions

    Science.gov (United States)

    Teolis, B. D.; Wyrick, D. Y.; Bouquet, A.; Magee, B. A.; Waite, J. H.

    2017-03-01

    A Europa plume source, if present, may produce a global exosphere with complex spatial structure and temporal variability in its density and composition. To investigate this interaction we have integrated a water plume source containing multiple organic and nitrile species into a Europan Monte Carlo exosphere model, considering the effect of Europa's gravity in returning plume ejecta to the surface, and the subsequent spreading of adsorbed and exospheric material by thermal desorption and re-sputtering across the entire body. We consider sputtered, radiolytic and potential plume sources, together with surface adsorption, regolith diffusion, polar cold trapping, and re-sputtering of adsorbed materials, and examine the spatial distribution and temporal evolution of the exospheric density and composition. These models provide a predictive basis for telescopic observations (e.g. HST, JWST) and planned missions to the Jovian system by NASA and ESA. We apply spacecraft trajectories to our model to explore possible exospheric compositions which may be encountered along proposed flybys of Europa to inform the spatial and temporal relationship of spacecraft measurements to surface and plume source compositions. For the present preliminary study, we have considered four cases: Case A: an equatorial flyby through a sputtered only exosphere (no plumes), Case B: a flyby over a localized sputtered 'macula' terrain enriched in non-ice species, Case C: a south polar plume with an Enceladus-like composition, equatorial flyby, and Case D: a south polar plume, flyby directly through the plume.

  8. Automatic Estimation of Volcanic Ash Plume Height using WorldView-2 Imagery

    Science.gov (United States)

    McLaren, David; Thompson, David R.; Davies, Ashley G.; Gudmundsson, Magnus T.; Chien, Steve

    2012-01-01

    We explore the use of machine learning, computer vision, and pattern recognition techniques to automatically identify volcanic ash plumes and plume shadows, in WorldView-2 imagery. Using information of the relative position of the sun and spacecraft and terrain information in the form of a digital elevation map, classification, the height of the ash plume can also be inferred. We present the results from applying this approach to six scenes acquired on two separate days in April and May of 2010 of the Eyjafjallajokull eruption in Iceland. These results show rough agreement with ash plume height estimates from visual and radar based measurements.

  9. Flowfield and Radiation Analysis of Missile Exhaust Plumes Using a Turbulent-Chemistry Interaction Model

    National Research Council Canada - National Science Library

    Calhoon, W. H; Kenzakowski, D. C

    2000-01-01

    ... components and missile defense systems. Current engineering level models neglect turbulent-chemistry interactions and typically underpredict the intensity of plume afterburning and afterburning burnout...

  10. Assessment of Turbulence-Chemistry Interactions in Missile Exhaust Plume Signature Analysis

    National Research Council Canada - National Science Library

    Calhoon, W

    2002-01-01

    ... components and missile defense systems. Current engineering level models neglect turbulence chemistry interactions and typically underpredict the intensity of plume afterburning and afterburning burnout...

  11. Characterization of ultrafast laser-ablation plasma plumes at various Ar ambient pressures

    Science.gov (United States)

    Diwakar, P. K.; Harilal, S. S.; Phillips, M. C.; Hassanein, A.

    2015-07-01

    Recently, we reported morphological changes in ultrafast laser ablation plumes in varying ambient pressures [Diwakar et al., J. Appl. Phys. 116, 133301 (2014)]. In this paper, we report the emission features of fs laser ablated brass plasma plumes at various Ar background pressure levels ranging from vacuum to atmospheric conditions and correlated to changes in plume morphology. Spatially resolved wavelength dispersed images of the plume were recorded for characterizing the spectral features at various pressure levels and also used for obtaining spatial distribution of Cu I and Zn I species in the plume, signal-to-noise ratios, and fundamental parameters of the plasma, specifically temperature and density. The spatial evolution of plasma temperature and density showed significant changes at various ambient pressure levels; these results were correlated to morphological changes seen in the plume images. Optical time-of-flight profiles were used to study time evolution of various species in the plume and indicated oscillations of ablation plumes at intermediate pressure levels. Possible mechanisms for observed changes in plume shape, optical emission intensity, and dual peak structures in time-of-flight profiles are discussed.

  12. The Thermal Evolution of the Galapagos Mantle Plume: Insights from Al-in-Olivine Thermometry

    Science.gov (United States)

    Trela, J.; Gazel, E.; Sobolev, A. V.; Class, C.; Bizimis, M.; Jicha, B. R.; Batanova, V. G.; Denyer, P.

    2016-12-01

    The mantle plume hypothesis is widely accepted for the formation of large igneous provinces (LIP) and many ocean island basalts (OIB). Petrologic models support a mantle plume origin by indicating high mantle temperatures (>1500 °C) for some plume-melts relative to melts generated at ambient mid ocean ridge conditions (1350 °C). Mantle plumes forming LIPs and OIBs provide our primary source of information on the geochemical and lithological heterogeneity of the lower mantle. The Galapagos hotspot represents one of the most thermally and geochemically heterogeneous plumes on the planet, sustaining long-lived isotopic and lithological heterogeneity over its 90 Ma evolution. Previous petrologic studies showed that the Galapagos plume secularly cooled over time and that the decrease in the plume's temperature correlates with an increase in a recycled (pyroxenite) component. We used Al-in-olivine thermometry to show that maximum olivine crystallization temperatures confirm secular cooling of the Galapagos plume. Olivines from the early melting stages of the plume at 90 Ma (Caribbean LIP) record the highest crystallization temperatures (1600 °C). Olivines from the current archipelago record the lowest temperatures of only 1300 °C. The largest decrease in temperature occurred between 90 and 70 Ma ( 200 °C decrease) and coincides with the plume head-tail transition. Olivines from the 60-90 Ma-old accreted Galapagos-tracks in Costa Rica and Panama record higher Ni, Fe/Mn, and lower Ca contents than those from the present-day archipelago, indicating a higher abundance of pyroxenite (recycled oceanic crust) entrained in parts of the plume head that melted to form the Caribbean LIP. However, the Galapagos plume was pyroxenite-rich for 40 Ma thus pyroxenite-entrainment goes beyond the plume-tail transition. Our results suggest that hotter regions of the Galapagos plume entrained larger amounts of dense, recycled components due to their greater buoyancy; however, this

  13. CO2 plume management in saline reservoir sequestration

    Science.gov (United States)

    Frailey, S.M.; Finley, R.J.

    2011-01-01

    A significant difference between injecting CO2 into saline aquifers for sequestration and injecting fluids into oil reservoirs or natural gas into aquifer storage reservoirs is the availability and use of other production and injection wells surrounding the primary injection well(s). Of major concern for CO2 sequestration using a single well is the distribution of pressure and CO2 saturation within the injection zone. Pressure is of concern with regards to caprock integrity and potential migration of brine or CO2 outside of the injection zone, while CO2 saturation is of interest for storage rights and displacement efficiency. For oil reservoirs, the presence of additional wells is intended to maximize oil recovery by injecting CO2 into the same hydraulic flow units from which the producing wells are withdrawing fluids. Completing injectors and producers in the same flow unit increases CO2 throughput, maximizes oil displacement efficiency, and controls pressure buildup. Additional injectors may surround the CO2 injection well and oil production wells in order to provide external pressure to these wells to prevent the injected CO2 from migrating from the pattern between two of the producing wells. Natural gas storage practices are similar in that to reduce the amount of "cushion" gas and increase the amount of cycled or working gas, edge wells may be used for withdrawal of gas and center wells used for gas injection. This reduces loss of gas to the formation via residual trapping far from the injection well. Moreover, this maximizes the natural gas storage efficiency between the injection and production wells and reduces the areal extent of the natural gas plume. Proposed U.S. EPA regulations include monitoring pressure and suggest the "plume" may be defined by pressure in addition to the CO2 saturated area. For pressure monitoring, it seems that this can only be accomplished by injection zone monitoring wells. For pressure, these wells would not need to be very

  14. Lidar detection of carbon dioxide in volcanic plumes

    Science.gov (United States)

    Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Maio, Giovanni; Del Franco, Mario; Aiuppa, Alessandro

    2015-06-01

    Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidar has been undertaken at the Diagnostics and Metrology Laboratory (UTAPRAD-DIM) of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high spatial and temporal resolution. Two differential absorption lidar instruments will be presented in this paper: BILLI (BrIdge voLcanic LIdar), based on injection seeded Nd:YAG laser, double grating dye laser, difference frequency mixing (DFM) and optical parametric amplifier (OPA), and VULLI (VULcamed Lidar), based on injection seeded Nd:YAG laser and optical parametric oscillator (OPO). The first one is funded by the ERC (European Research Council) project BRIDGE and the second one by the ERDF (European Regional Development Fund) project VULCAMED. While VULLI has not yet been tested in a volcanic site, BILLI scanned the gas emitted by Pozzuoli Solfatara (Campi Flegrei volcanic area, Naples, Italy) during a field campaign carried out from 13 to 17 October 2014. Carbon dioxide concentration maps were retrieved remotely in few minutes in the crater area. Lidar measurements were in good agreement with well-established techniques, based on different operating principles. To our knowledge, it is the first time that carbon dioxide in a volcanic plume is retrieved by lidar, representing the first direct measurement of this kind ever performed on an active volcano and showing the high potential of laser remote sensing in geophysical research.

  15. Rocket plume temperature measurement by wire welded thermocouples

    Science.gov (United States)

    Xu, Qiang

    2006-05-01

    The plume of solid rocket motor is a high velocity flow with high temperature. Temperature distribution in the plume is of great interest for analyzing the compatibility of rocket weapon system. The high temperature exhausted flow field would cause damage on certain equipment and loading vehicles. An instantaneous temperature field with sharp step is established by the exhausted flow field of rocket motor. The increasing rate of the step depends on the flow velocity at cross section of nozzle exit. To perform an accurate measurement of temperature inside the flow field, a thermocouple must be sturdy enough to endure the flow impingement. In the meantime, the thermocouple must have a short time constant to trace the temperature fluctuation in flow field and a small size to avoid disturbing the flow field severely. The dynamic performance of the thermocouples used in exhausted flow temperature measurement must be evaluated before the experiment. The thermocouple which can be used in measuring the temperature distribution in rocket plume was presented in this paper. A NAMNAC (R) self-renew-erode thermocouples with a nominal time constant of 10 microseconds was used as a reference in a dynamic calibration test for this kind of thermocouple. The thermocouple could trace the temperature increase in the exhausted flow perfectly. This kind of thermocouples was used in several real tests of rocket motors, such as the temperature in free exhausted flow field of a stationary rocket motor test, the stagnate temperature in a shock flow field during the launching of a rocket, and the temperature in a launch tube.

  16. Plume-driven plumbing and crustal formation in Iceland

    Science.gov (United States)

    Allen, R.M.; Nolet, G.; Morgan, W.J.; Vogfjord, K.; Nettles, M.; Ekstrom, G.; Bergsson, B.H.; Erlendsson, P.; Foulger, G.R.; Jakobsdottir, S.; Julian, B.R.; Pritchard, M.; Ragnarsson, S.; Stefansson, R.

    2002-01-01

    Through combination of surface wave and body wave constraints we derive a three-dimensional (3-D) crustal S velocity model and Moho map for Iceland. It reveals a vast plumbing system feeding mantle plume melt into upper crustal magma chambers where crustal formation takes place. The method is based on the partitioned waveform inversion to which we add additional observations. Love waves from six local events recorded on the HOTSPOT-SIL networks are fitted, Sn travel times from the same events measured, previous observations of crustal thickness are added, and all three sets of constraints simultaneously inverted for our 3-D model. In the upper crust (0-15 km) an elongated low-velocity region extends along the length of the Northern, Eastern and Western Neovolcanic Zones. The lowest velocities (-7%) are found at 5-10 km below the two most active volcanic complexes: Hekla and Bardarbunga-Grimsvotn. In the lower crust (>15 km) the low-velocity region can be represented as a vertical cylinder beneath central Iceland. The low-velocity structure is interpreted as the thermal halo of pipe work which connects the region of melt generation in the uppermost mantle beneath central Iceland to active volcanoes along the neovolcanic zones. Crustal thickness in Iceland varies from 15-20 km beneath the Reykjanes Peninsula, Krafla and the extinct Snfellsnes rift zone, to 46 km beneath central Iceland. The average crustal thickness is 29 km. The variations in thickness can be explained in terms of the temporal variation in plume productivity over the last ~20 Myr, the Snfellsnes rift zone being active during a minimum in plume productivity. Variations in crustal thickness do not depart significantly from an isostatically predicted crustal thickness. The best fit linear isostatic relation implies an average density jump of 4% across the Moho. Rare earth element inversions of basalt compositions on Iceland suggest a melt thickness (i.e., crustal thickness) of 15-20 km, given passive

  17. Atmospheric ventilation corridors and coefficients for pollution plume ...

    African Journals Online (AJOL)

    Tuoyo Aghomotsegin

    for gaseous pollution plume released from an isolated industrial facility into the ambient air of the host ... from industrial facilities are required for assessment of ..... 1.17. 0.71. Year 2013. Year 2013. Sept. 14.6. 27.4. 26.4. 16.5. 8.0. 4.8. 2.2. 1.2. 5.2. 1.25. 0.63. Oct. 35.8. 20.7. 21.0. 14.8. 5.2. 1.9. 0.7. 0.9. 4.0. 0.91. 0.83. Nov.

  18. Behavioural response of silver eel to effluent plumes: Telemetry experiments

    OpenAIRE

    Winter, H.V.; Keeken, van, O.A.; Foekema, E.M.; Kleissen, F.; Friocourt, Y.; Beare, D.J.

    2011-01-01

    Fish migration may be hampered by a range of physical barriers. That non-physical barriers such as sudden changes in water quality may also serve as barriers is often stated, but only very few studies address this issue. This study focusses on linking the behavioural response of silver eel and river lamprey when encountering a waste water plume (effluent) in field situations. Individual fish movements were tracked by means of acoustic telemetry in 2D (in 2009) and in 3D (in 2010) at a locatio...

  19. Energetic plumes over the western Ross Sea continental slope

    OpenAIRE

    Gordon, A.; Zambianchi, E.; A. Orsi; Visbeck, Martin; Giulivi, C; Whitworth, T.; Spezie, G.

    2004-01-01

    Rapid descent of dense Drygalski Trough (western Ross Sea, Antarctica) shelf water over the continental slope, within 100 to 250 m thick benthic plumes, is described. Speeds of up to 1.0 m/s are recorded flowing at an average angle of 35° to the isobaths, entraining ambient Lower Circumpolar Deep Water en route. This process is predominant in determining the concentration and placement of the shelf water injected into the deep sea as a precursor Antarctic Bottom Water. Nonetheless, a 4-hour d...

  20. Les Plumes du Dragon, ou comment sont morts les chevaliers

    OpenAIRE

    Boulaire, Cécile

    1998-01-01

    Cet article a obtenu le Prix de la Critique (catégorie meilleur article inédit) de l’Institut International Charles Perrault en 1998.; International audience; Les Plumes du Dragon est un album pour enfants. Tout ce qui va suivre semble contredire cette première affirmation, pourtant ce livre, qui reprend un conte traditionnel dont les frères Grimm avaient donné une version , est toujours proposé dans les rayons “littérature enfantine” des librairies. Ses illustrateurs, Olga et Andrej Dugin, a...

  1. Plume Delineation in the BC Cribs and Trenches Area

    Energy Technology Data Exchange (ETDEWEB)

    Rucker, Dale F.; Sweeney, Mark D.

    2004-11-30

    HydroGEOPHYSICS, Inc. and Pacific Northwest National Laboratory (PNNL) were contracted by Fluor Hanford Group, Inc. to conduct a geophysical investigation in the area of the BC Cribs and Trenches (subject site) at the Hanford Site in Richland, Washington. The BC Cribs and Trenches are located south of the 200 East Area. This document provides the details of the investigation to identify existing infrastructure from legacy disposal activities and to delineate the edges of a groundwater plume that contains radiological and heavy metal constituents beneath the 216-B-26 and 216-B-52 Trenches, and the 216-B-14 through 216-B-19 Cribs.

  2. Estimation and Modeling of Enceladus Plume Jet Density Using Reaction Wheel Control Data

    Science.gov (United States)

    Lee, Allan Y.; Wang, Eric K.; Pilinski, Emily B.; Macala, Glenn A.; Feldman, Antonette

    2010-01-01

    The Cassini spacecraft was launched on October 15, 1997 by a Titan 4B launch vehicle. After an interplanetary cruise of almost seven years, it arrived at Saturn on June 30, 2004. In 2005, Cassini completed three flybys of Enceladus, a small, icy satellite of Saturn. Observations made during these flybys confirmed the existence of a water vapor plume in the south polar region of Enceladus. Five additional low-altitude flybys of Enceladus were successfully executed in 2008-9 to better characterize these watery plumes. The first of these flybys was the 50-km Enceladus-3 (E3) flyby executed on March 12, 2008. During the E3 flyby, the spacecraft attitude was controlled by a set of three reaction wheels. During the flyby, multiple plume jets imparted disturbance torque on the spacecraft resulting in small but visible attitude control errors. Using the known and unique transfer function between the disturbance torque and the attitude control error, the collected attitude control error telemetry could be used to estimate the disturbance torque. The effectiveness of this methodology is confirmed using the E3 telemetry data. Given good estimates of spacecraft's projected area, center of pressure location, and spacecraft velocity, the time history of the Enceladus plume density is reconstructed accordingly. The 1-sigma uncertainty of the estimated density is 7.7%. Next, we modeled the density due to each plume jet as a function of both the radial and angular distances of the spacecraft from the plume source. We also conjecture that the total plume density experienced by the spacecraft is the sum of the component plume densities. By comparing the time history of the reconstructed E3 plume density with that predicted by the plume model, values of the plume model parameters are determined. Results obtained are compared with those determined by other Cassini science instruments.

  3. Thermally-Driven Mantle Plumes Reconcile Hot-spot Observations

    Science.gov (United States)

    Davies, D.; Davies, J.

    2008-12-01

    Hot-spots are anomalous regions of magmatism that cannot be directly associated with plate tectonic processes (e.g. Morgan, 1972). They are widely regarded as the surface expression of upwelling mantle plumes. Hot-spots exhibit variable life-spans, magmatic productivity and fixity (e.g. Ito and van Keken, 2007). This suggests that a wide-range of upwelling structures coexist within Earth's mantle, a view supported by geochemical and seismic evidence, but, thus far, not reproduced by numerical models. Here, results from a new, global, 3-D spherical, mantle convection model are presented, which better reconcile hot-spot observations, the key modification from previous models being increased convective vigor. Model upwellings show broad-ranging dynamics; some drift slowly, while others are more mobile, displaying variable life-spans, intensities and migration velocities. Such behavior is consistent with hot-spot observations, indicating that the mantle must be simulated at the correct vigor and in the appropriate geometry to reproduce Earth-like dynamics. Thermally-driven mantle plumes can explain the principal features of hot-spot volcanism on Earth.

  4. Thermal radiation from large bolides and impact plumes

    Science.gov (United States)

    Svetsov, V.; Shuvalov, V.

    2017-09-01

    Numerical simulations of the impacts of asteroids and comets from 20 m to 3 km in diameter have been carried out and thermal radiation fluxes on the ground and luminous efficiencies of the impacts have been calculated. It was assumed that the cosmic objects have no strength, deform, fragment, and vaporize in the atmosphere. After the impact on the ground, formation of craters and plumes was simulated taking into account internal friction of destroyed rocks and a wake formed in the atmosphere. The equations of radiative transfer, added to the equations of gas dynamics, were used in the approximation of radiative heat diffusion or, if the Rosseland optical depth of a radiating volume of gas and vapor was less than unity, in the approximation of volume emission. Radiation fluxes on the Earth's surface were calculated by integrating the equation of radiative transfer along rays passing through a luminous area. Direct thermal radiation from fireballs and impact plumes produced by asteroids and comets larger than 50 m in diameter is dangerous for people, animals, plants, economic objects. Forest fires can be ignited on the ground within a radius of roughly 1000 times the body's diameter (for diameters of the order or smaller than 1 km), 50-m-diameter bodies can ignite forest fires within a radius of up to 40 km and 3-km asteroids - within 1700 km.

  5. An extremely high altitude plume seen at Mars morning terminator

    Science.gov (United States)

    Sanchez-Lavega, Agustin; Garcia-Muñoz, Antonio; Garcia-Melendo, Enrique; Perez-Hoyos, Santiago; Gomez-Forrellad, Josep M.; Pellier, Christophe; Delcroix, Marc; Lopez-Valverde, Miguel Angel; Gonzalez-Galindo, Francisco; Jaeschke, Wayne; Parker, Donald C.; Phillips, James H.; Peach, Damian

    2014-11-01

    We report the occurrence in March and April 2012 of two bright very high altitude plumes at the Martian terminator at 250 km or more above the surface, thus well into the ionosphere and bordering on the exosphere. They were located at about 195 deg West longitude and -45 deg latitude (at Terra Cimmeria) and lasted for about 10 days. The features showed day-to-day variability, and were seen at the morning terminator but not at the evening limb, which indicates rapid evolution in less than 10 hours and a cyclic behavior. Photometric measurements are used to explore two possible scenarios to explain their nature. If the phenomenon is due to suspended particles (dust, CO2 or H2O ice clouds) reflecting solar radiation, the mean size is about 0.1 microns with a nadir optical depth > 0.06. Alternatively, the plume could be auroral emission above a region with a strong magnetic anomaly and where aurora has previously been detected. Importantly, both explanations defy our current understanding of the Mars upper atmosphere.AcknowledgementsThis work was supported by the Spanish MINECO projects AYA2012-36666 with FEDER support, CONSOLIDER program ASTROMOL CSD2009-00038 and AYA2011-30613-CO2-1. Grupos Gobierno Vasco IT765-13 and UPV/EHU UFI11/55.

  6. Pockmark morphology and turbulent buoyant plumes at a submarine spring

    Science.gov (United States)

    Buongiorno Nardelli, B.; Budillon, F.; Watteaux, R.; Ciccone, F.; Conforti, A.; De Falco, G.; Di Martino, G.; Innangi, S.; Tonielli, R.; Iudicone, D.

    2017-09-01

    The input flow of groundwater from the seabed to the coastal ocean, known as Submarine Groundwater Discharge (SGD), has been only recently recognized as an important component of continental margin systems. It potentially impacts physical, chemical and biological marine dynamics. Independently of its specific nature (seepage, submarine springs, etc.) or fluid chemical composition, a SGD is generally characterized by low flow rates, hence making its detection and quantification very difficult, and explaining why it has been somewhat neglected by the scientific community for a long time. Along with the growing interest for SGDs emerged the need for in-situ observations in order to characterize in details how these SGDs behave. In this work, we describe the morphology of a pockmark field, detected in the Southern Tyrrhenian Sea (Mediterranean Sea), and provide observational evidences of the presence of active submarine springs over the coastal shelf area. We describe the effect of the fluid seeps on the water column stratification close to the main plumes and in the neighbouring areas, providing quantitative estimates of the intensity of the turbulent mixing and discussing their potential impact on the seabed morphology and pockmark formation in the context of turbulent buoyant plumes analytical modelling.

  7. Unveiling CO2 heterogeneous freezing plumes during champagne cork popping.

    Science.gov (United States)

    Liger-Belair, Gérard; Cordier, Daniel; Honvault, Jacques; Cilindre, Clara

    2017-09-14

    Cork popping from clear transparent bottles of champagne stored at different temperatures (namely, 6, 12, and 20 °C) was filmed through high-speed video imaging in the visible light spectrum. During the cork popping process, a plume mainly composed of gaseous CO2 with traces of water vapour freely expands out of the bottleneck through ambient air. Most interestingly, for the bottles stored at 20 °C, the characteristic grey-white cloud of fog classically observed above the bottlenecks of champagne stored at lower temperatures simply disappeared. It is replaced by a more evanescent plume, surprisingly blue, starting from the bottleneck. We suggest that heterogeneous freezing of CO2 occurs on ice water clusters homogeneously nucleated in the bottlenecks, depending on the saturation ratio experienced by gas-phase CO2 after adiabatic expansion (indeed highly bottle temperature dependent). Moreover, and as observed for the bottles stored at 20 °C, we show that the freezing of only a small portion of all the available CO2 is able to pump the energy released through adiabatic expansion, thus completely inhibiting the condensation of water vapour found in air packages adjacent to the gas volume gushing out of the bottleneck.

  8. Wet Cold Plumes as Revealed by One Billion Tracers

    Science.gov (United States)

    Gerya, T.; Yuen, D. A.; Rudolph, M.; Capel, A.; Sevre, E. O.

    2004-05-01

    We have modeled the dynamics of plume development above subducting slabs. Our 2-D model incorporates the effects of thermal-chemical buoyancy as well as the combined effects of both hydration and melting. We have used up to ONE BILLION tracers to delineate the evolution of the lithological, rheological and deformation structure of subduction zone with resolution down to between 10 and 50 meters. In contrast to common thinking that hot rising mantle flows prevail in the mantle wedge above the subducting slab our results suggest that partially molten hydrated upwellings (WET COLD PLUMES) in the mantle wedge are characterized by a colder thermal anomaly of 300 to 400 degrees! The process is propelled by the subduction of buoyant crustal rocks and infiltration of aqueous fluids releasing from the slab, particularly due to decomposition of serpentine at depths >100 km. Low viscosity of these silicate bearing fluids under subsolidus conditions results in a rapid upward transport of water from the slab toward the melting front that forms within the mantle wedge. This melting front lies nearly parallel to the slab and is located just a few kilometers atop the slab. Higher viscosity and slower infiltration of hydrous basaltic melts formed above the melting front produces a slab-parallel layer of partially molten peridotite which is the source layer for the unmixed cold plumes transporting magmas of peridotitic origin. Mixed cold plumes responsible for transportation of crustal and mixed magmas starts directly from the slab and consist of hydrated, partially molten both mantle and subducted crustal rocks mixed on hundreds to tens of meter scale. Unmixed and mixed wave-like structures were also observed and they propagate upward along descending slabs. Both cold plumes and cold waves may have an upward velocity >1 m/year rapidly transporting thousands of cubic kilometers of rocks and magmas. Visualizing one billion tracers is a daunting task, as there is no single display

  9. Biological Ocean Margins Program. Active Microbes Responding to Inputs from the Orinoco River Plume. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Jorge E. Corredor

    2013-01-28

    The overall goal of the proposed work is to identify the active members of the heterotrophic community involved in C and N cycling in the perimeter of the Orinoco River Plume (ORP), assess their spatial distribution, quantify their metabolic activity, and correlate these parameters to plume properties such as salinity, organic matter content and phytoplankton biomass.

  10. Eyjafjallajokull Volcano Plume Particle-Type Characterization from Space-Based Multi-angle Imaging

    Science.gov (United States)

    Kahn, Ralph A.; Limbacher, James

    2012-01-01

    The Multi-angle Imaging SpectroRadiometer (MISR) Research Aerosol algorithm makes it possible to study individual aerosol plumes in considerable detail. From the MISR data for two optically thick, near-source plumes from the spring 2010 eruption of the Eyjafjallaj kull volcano, we map aerosol optical depth (AOD) gradients and changing aerosol particle types with this algorithm; several days downwind, we identify the occurrence of volcanic ash particles and retrieve AOD, demonstrating the extent and the limits of ash detection and mapping capability with the multi-angle, multi-spectral imaging data. Retrieved volcanic plume AOD and particle microphysical properties are distinct from background values near-source, as well as for overwater cases several days downwind. The results also provide some indication that as they evolve, plume particles brighten, and average particle size decreases. Such detailed mapping offers context for suborbital plume observations having much more limited sampling. The MISR Standard aerosol product identified similar trends in plume properties as the Research algorithm, though with much smaller differences compared to background, and it does not resolve plume structure. Better optical analogs of non-spherical volcanic ash, and coincident suborbital data to validate the satellite retrieval results, are the factors most important for further advancing the remote sensing of volcanic ash plumes from space.

  11. Surface fire effects on conifer and hardwood crowns--applications of an integral plume model

    Science.gov (United States)

    Matthew Dickinson; Anthony Bova; Kathleen Kavanagh; Antoine Randolph; Lawrence Band

    2009-01-01

    An integral plume model was applied to the problems of tree death from canopy injury in dormant-season hardwoods and branch embolism in Douglas fir (Pseudotsuga menziesii) crowns. Our purpose was to generate testable hypotheses. We used the integral plume models to relate crown injury to bole injury and to explore the effects of variation in fire...

  12. USING DIRECT-PUSH TOOLS TO MAP HYDROSTRATIGRAPHY AND PREDICT MTBE PLUME DIVING

    Science.gov (United States)

    MTBE plumes have been documented to dive beneath screened intervals of conventional monitoring well networks at a number of LUST sites. This behavior makes these plumes difficult both to detect and remediate. Electrical conductivity logging and pneumatic slug testing performed in...

  13. A CATALOG OF GROUND WATER FLOW SOLUTIONS FOR PLUME DIVING CALCULATIONS

    Science.gov (United States)

    This report focuses on the problem of diving plumes, a term which generally refers to plumes that go deeper into aquifers with distances from their sources. This document presents the mathematical basis of software for real-time development and refinement of site conceptual model...

  14. Impact of boundary conditions on the development of the thermal plume above a sitting human body

    DEFF Research Database (Denmark)

    Zukowska, Daria; Popiolek, Zbigniew J.; Melikov, Arsen Krikor

    2010-01-01

    The phenomenon of the thermal plume above a heat source has been reported in the literature as being influenced by a large number of factors. The objective of the present study is to identify the impact of the boundary conditions on the characteristics and development of the thermal plume above...

  15. Remote Sensing and Underwater Glider Observations of a Springtime Plume in Western Lake Superior

    Science.gov (United States)

    Plumes are commonly observed in satellite imagery of western Lake Superior following storm events, and represent a significant cross-shelf pathway for sediment and other constituents. However, their subsurface extent is poorly understood. This study reports results from plume ob...

  16. Expansion of a laser-produced silver plume in light background gases

    DEFF Research Database (Denmark)

    Amoruso, S.; Toftmann, B.; Schou, Jørgen

    2004-01-01

    The expansion of a silver ablation plume in a helium and an argon background gas has been studied over the pressure range 10(-6) to 1 mbar. The angular distribution of silver atoms deposited on an array of quartz-crystal microbalances as well as time-of-flight signals of the plume ions in both...

  17. Ship plume dispersion rates in convective boundary layers for chemistry models

    Directory of Open Access Journals (Sweden)

    F. Chosson

    2008-08-01

    Full Text Available Detailed ship plume simulations in various convective boundary layer situations have been performed using a Lagrangian Dispersion Model driven by a Large Eddy Simulation Model. The simulations focus on the early stage (1–2 h of plume dispersion regime and take into account the effects of plume rise on dispersion. Results are presented in an attempt to provide to atmospheric chemistry modellers a realistic description of characteristic dispersion impact on exhaust ship plume chemistry. Plume dispersion simulations are used to derive analytical dilution rate functions. Even though results exhibit striking effects of plume rise parameter on dispersion patterns, it is shown that initial buoyancy fluxes at ship stack have a minor effect on plume dilution rate. After initial high dispersion regimes a simple characteristic dilution time scale can be used to parameterize the subgrid plume dilution effect in large-scale chemistry models. The results show that this parameter is directly related to the typical turn-over time scale of the convective boundary layer.

  18. Hydrodynamics in the mid-field plume region of the Rhine ROFI

    NARCIS (Netherlands)

    Rijnsburger, S.; Audibert, R.F.; Souza, Alejandro J.; Horner-Devine, Alexander R.; Pietrzak, J.D.

    2016-01-01

    River plumes, also regions of freshwater influence , are important features to understand because of their impact on the current structure, stratification and the transport of fine sediments, nutrients and contaminants. One important river plume is the Rhine ROFI. Prior studies have sought to

  19. Cross shore transport by wind-driven turbidity plumes in western Lake Superior

    Science.gov (United States)

    Turbidity plumes frequently occur in the western arm of Lake Superior and may represent a significant cross shelf transport mechanism for sediment, nutrient and organisms. We characterize a plume that formed in late April 2016 using observations from a suite of in situ sensors an...

  20. Long-distance impact of Iceland plume on Norway’s rifted margin

    National Research Council Canada - National Science Library

    Alexander Koptev; Sierd Cloetingh; Evgueni Burov; Thomas François; Taras Gerya

    2017-01-01

    ... from the Iceland mantle plume has been the norm in the geological past. In the Northern Atlantic the Iceland plume has a strong long-distance impact on intraplate deformation affecting both onshore and offshore parts of Norway’s rifted margin...

  1. The EUV Spectrum of Sunspot Plumes Observed by SUMER on SOHO

    Indian Academy of Sciences (India)

    In sunspot plumes the EUV spectrum differs from the quiet Sun; continua are observed with different slopes and intensities; emission lines from molecular hydrogen and many unidentified species indicate unique plasma conditions above sunspots. Sunspot plumes are sites of systematic downflow. We also discuss the ...

  2. Low Density Supersonic Decelerator (LDSD) Supersonic Flight Dynamics Test (SFDT) Plume Induced Environment Modelling

    Science.gov (United States)

    Mobley, B. L.; Smith, S. D.; Van Norman, J. W.; Muppidi, S.; Clark, I

    2016-01-01

    Provide plume induced heating (radiation & convection) predictions in support of the LDSD thermal design (pre-flight SFDT-1) Predict plume induced aerodynamics in support of flight dynamics, to achieve targeted freestream conditions to test supersonic deceleration technologies (post-flight SFDT-1, pre-flight SFDT-2)

  3. Natural attenuation processes in landfill leachate plumes at three Danish sites

    DEFF Research Database (Denmark)

    Bjerg, Poul Løgstrup; Tuxen, Nina; Reitzel, Lotte

    2011-01-01

    . The research performed serves as good case studies to conceptualize natural attenuation processes in landfill leachate plumes and also supports the notion that monitored natural attenuation (MNA) may be a possible remediation strategy at landfills. However, landfill leachate plumes challenge traditional...

  4. Radiation from Rocket Exhaust Plumes. Part 1; Inhomogeneous Radiant Heat Transfer from Saturn Type Rocket Exhaust Plumes

    Science.gov (United States)

    Huffaker, Robert M.; Carlson, Donald J.

    1966-01-01

    A radiant heat transfer computer program has been developed by R-AERO-A to calculate radiation from inhomogeneous gases prevalent in Saturn-type exhaust plumes. The radiating species considered in this computer program are water vapor, carbon dioxide, carbon monoxide and carbon particles. The infrared spectral absorption characteristics of these species have been determined under NASA contract. Band model parameters have been used to represent the infrared spectral absorption coefficients over 25 cm-I increments. A modified Curtis-Goodson approximation is used in the inhomogeneous heat transfer calculation. This has been shown to give satisfactory results over the temperature and pressure range of interest in Saturn exhaust plumes. Results are shown for the Saturn-type engines for specific flow field assumptions. Some comparison with experimental spectroscopic data will also be presented. The effect of wavelength increment, field of view, and distance increment along the line of sight on the heat transfer will be discussed. Computer techniques for minimum computer time in calculating radiation from a three-dimensional flow field will also be outlined.

  5. The source location of mantle plumes from 3D spherical models of mantle convection

    Science.gov (United States)

    Li, Mingming; Zhong, Shijie

    2017-11-01

    Mantle plumes are thought to originate from thermal boundary layers such as Earth's core-mantle boundary (CMB), and may cause intraplate volcanism such as large igneous provinces (LIPs) on the Earth's surface. Previous studies showed that the original eruption sites of deep-sourced LIPs for the last 200 Myrs occur mostly above the margins of the seismically-observed large low shear velocity provinces (LLSVPs) in the lowermost mantle. However, the mechanism that leads to the distribution of the LIPs is not clear. The location of the LIPs is largely determined by the source location of mantle plumes, but the question is under what conditions mantle plumes form outside, at the edges, or above the middle of LLSVPs. Here, we perform 3D geodynamic calculations and theoretical analyses to study the plume source location in the lowermost mantle. We find that a factor of five decrease of thermal expansivity and a factor of two increase of thermal diffusivity from the surface to the CMB, which are consistent with mineral physics studies, significantly reduce the number of mantle plumes forming far outside of thermochemical piles (i.e., LLSVPs). An increase of mantle viscosity in the lowermost mantle also reduces number of plumes far outside of piles. In addition, we find that strong plumes preferentially form at/near the edges of piles and are generally hotter than that forming on top of piles, which may explain the observations that most LIPs occur above LLSVP margins. However, some plumes originated at pile edges can later appear above the middle of piles due to lateral movement of the plumes and piles and morphologic changes of the piles. ∼65-70% strong plumes are found within 10 degrees from pile edges in our models. Although plate motion exerts significant controls over the large-scale mantle convection in the lower mantle, mantle plume formation at the CMB remains largely controlled by thermal boundary layer instability which makes it difficult to predict geographic

  6. A Critical study on Fire-induced Aerodynamics of Balcony Spill Plumes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Balcony spill plume is one of the main plume forms in an atrium fh'e, its thermal behavior which is important to the designers for the smoke control system design is still not well understood now. The fire-induced aerodynamics of balcony spill plume would be studied by the numerical method in this paper. Some uncertainties relating to the available calculation methods for the smoke production rate would be reexamined. Numerical results indicated that using an entrainment coefficient 0.11 would be better than 0.16 in describing the entrainment behavior, end effect should not be ignored for the plume being not two-dimensional (2-D). Suitable empirical spill plume equations would be recommended for the smoke management system design.

  7. A critical study on fire-induced aerodynamics of balcony spill plumes

    Science.gov (United States)

    Li, Junmei; Li, Yanfeng; Liu, Yun; Xue, Suduo

    2008-09-01

    Balcony spill plume is one of the main plume forms in an atrium fire, its thermal behavior which is important to the designers for the smoke control system design is still not well understood now. The fire-induced aerodynamics of balcony spill plume would be studied by the numerical method in this paper. Some uncertainties relating to the available calculation methods for the smoke production rate would be reexamined. Numerical results indicated that using an entrainment coefficient 0.11 would be better than 0.16 in describing the entrainment behavior, end effect should not be ignored for the plume being not two-dimensional (2-D). Suitable empirical spill plume equations would be recommended for the smoke management system design.

  8. A preliminary experiment to collect gas from a submarine gas plume

    Science.gov (United States)

    Aoyama, C.; Fukuoka, H.

    2016-12-01

    Thousands of gas plumes have been found on the sea floors around Japan. Most of them are associated with methane hydrates on seafloor surface and/or shallow subsurface, and those bubbles are consisting largely of methane. Concerns are emerging about large scale plumes may provide the highly efficient greenhouse gas to the atmosphere. A novel methodology is proposed in this study, to collect those gas bubbles in the plumes using membrane-made dome to reduce global greenhouse effect and to develop new energy resources. Experiment field is northeast offshore of the Sado Island, Niigata prefecture of Japan, where more than 40 gas plumes had been found, gushing out from rather shallower sea floor of 150 - 400 m depth. Authors will present the achievement obtained in the preliminary gas collection experiment which was performed in a gas plume in this sea area in March 2016.

  9. The LIP-OIB transitional phase in the Galapagos mantle plume

    Science.gov (United States)

    Trela, J.; Gazel, E.; Vidito, C. A.; Class, C.; Jicha, B. R.; Bizimis, M.; Herzberg, C. T.; Alvarado-Induni, G.

    2014-12-01

    Although significant work has been done on LIPS and OIB, no complete record of the evolution of a mantle plume is available at this point. Galapagos-related lavas provide a complete record of the evolution of a mantle plume since the plume's initial stages in the Cretaceous. Our petrological models (PRIMELT2) suggest that the Galapagos plume head that formed the Caribbean Large Igneous Province (CLIP) at ~95 Ma melted at hotter temperatures than the ocean island basalt (OIB) equivalents of the modern archipelago. While this work suggests a significant decrease in mantle potential temperatures (Tp) over time, the exact mechanism responsible for secular cooling of the Galapagos plume remains unclear. One viable explanation is that plumes entraining recycled oceanic crust (pyroxenite) will be cooler than purely peridotite plumes, due to the effect of dense pyroxenite on the plume's buoyancy. High-precision electron microprobe analyses on olivine cores from the ~70 Ma Galapagos-related Quepos terrane in Costa Rica indicate a mixed peridotite-pyroxenite source lithology, not evident during the LIP stage. The appearance of this pyroxenitic component correlates with the first record of an EMII isotopic signature (Northern Galapagos Domain), and significant high-field strength enrichments in the Galapagos plume related lavas. This dense pyroxenite component may explain the marked decrease in Tp observed at ~70 Ma due to its effect on the plume's buoyancy. Otherwise, the pyroxenite component may have been diluted during voluminous basalt production of the CLIP by high peridotite melt fractions. Future research will incorporate further petrological modeling, olivine chemistry, and radiogenic isotope work of accreted Galapagos terranes in Central America to test whether or not a decrease in Tp correlates with increasing pyroxenite content in source melts.

  10. Tracking stormwater discharge plumes and water quality of the Tijuana River with multispectral aerial imagery

    Science.gov (United States)

    Svejkovsky, Jan; Nezlin, Nikolay P.; Mustain, Neomi M.; Kum, Jamie B.

    2010-04-01

    Spatial-temporal characteristics and environmental factors regulating the behavior of stormwater runoff from the Tijuana River in southern California were analyzed utilizing very high resolution aerial imagery, and time-coincident environmental and bacterial sampling data. Thirty nine multispectral aerial images with 2.1-m spatial resolution were collected after major rainstorms during 2003-2008. Utilizing differences in color reflectance characteristics, the ocean surface was classified into non-plume waters and three components of the runoff plume reflecting differences in age and suspended sediment concentrations. Tijuana River discharge rate was the primary factor regulating the size of the freshest plume component and its shorelong extensions to the north and south. Wave direction was found to affect the shorelong distribution of the shoreline-connected fresh plume components much more strongly than wind direction. Wave-driven sediment resuspension also significantly contributed to the size of the oldest plume component. Surf zone bacterial samples collected near the time of each image acquisition were used to evaluate the contamination characteristics of each plume component. The bacterial contamination of the freshest plume waters was very high (100% of surf zone samples exceeded California standards), but the oldest plume areas were heterogeneous, including both polluted and clean waters. The aerial imagery archive allowed study of river runoff characteristics on a plume component level, not previously done with coarser satellite images. Our findings suggest that high resolution imaging can quickly identify the spatial extents of the most polluted runoff but cannot be relied upon to always identify the entire polluted area. Our results also indicate that wave-driven transport is important in distributing the most contaminated plume areas along the shoreline.

  11. Modeling the effect of plume-rise on the transport of carbon monoxide over Africa with NCAR CAM

    OpenAIRE

    H. Guan; Chatfield, R. B.; S. R. Freitas; Bergstrom, R. W.; Longo, K. M.

    2008-01-01

    We investigated the effects of fire-induced plume-rise on the simulation of carbon monoxide (CO) over Africa and its export during SAFARI 2000 using the NCAR Community Atmosphere Model (CAM) with a CO tracer and a plume-rise parameterization scheme. The plume-rise parameterization scheme simulates the consequences of strong buoyancy of hot gases emitted from biomass burning, including both dry and cloud-associated (pyro-cumulus) lofting. The current implementation of the plume-rise parameteri...

  12. A multidisciplinary system for monitoring and forecasting Etna volcanic plumes

    Science.gov (United States)

    Coltelli, Mauro; Prestifilippo, Michele; Spata, Gaetano; Scollo, Simona; Andronico, Daniele

    2010-05-01

    One of the most active volcanoes in the world is Mt. Etna, in Italy, characterized by frequent explosive activity from the central craters and from fractures opened along the volcano flanks which, during the last years, caused several damages to aviation and forced the closure of the Catania International Airport. To give precise warning to the aviation authorities and air traffic controller and to assist the work of VAACs, a novel system for monitoring and forecasting Etna volcanic plumes, was developed at the Istituto Nazionale di Geofisica e Vulcanologia, sezione di Catania, the managing institution for the surveillance of Etna volcano. Monitoring is carried out using multispectral infrared measurements from the Spin Enhanced Visible and Infrared Imager (SEVIRI) on board the Meteosat Second Generation geosynchronous satellite able to track the volcanic plume with a high time resolution, visual and thermal cameras used to monitor the explosive activity, three continuous wave X-band disdrometers which detect ash dispersal and fallout, sounding balloons used to evaluate the atmospheric fields, and finally field data collected after the end of the eruptive event needed to extrapolate important features of explosive activity. Forecasting is carried out daily using automatic procedures which download weather forecast data obtained by meteorological mesoscale models from the Italian Air Force national Meteorological Office and from the hydrometeorological service of ARPA-SIM; run four different tephra dispersal models using input parameters obtained by the analysis of the deposits collected after few hours since the eruptive event similar to 22 July 1998, 21-24 July 2001 and 2002-03 Etna eruptions; plot hazard maps on ground and in air and finally publish them on a web-site dedicated to the Italian Civil Protection. The system has been already tested successfully during several explosive events occurring at Etna in 2006, 2007 and 2008. These events produced eruption

  13. Ash production by attrition in volcanic conduits and plumes.

    Science.gov (United States)

    Jones, T J; Russell, J K

    2017-07-17

    Tephra deposits result from explosive volcanic eruption and serve as indirect probes into fragmentation processes operating in subsurface volcanic conduits. Primary magmatic fragmentation creates a population of pyroclasts through volatile-driven decompression during conduit ascent. In this study, we explore the role that secondary fragmentation, specifically attrition, has in transforming primary pyroclasts upon transport in volcanic conduits and plumes. We utilize total grain size distributions from a suite of natural and experimentally produced tephra to show that attrition is likely to occur in all explosive volcanic eruptions. Our experimental results indicate that fine ash production and surface area generation is fast (eruption column stability, tephra dispersal, aggregation, volcanic lightening generation, and has concomitant effects on aviation safety and Earth's climate.

  14. Schlieren image velocimetry measurements in a rocket engine exhaust plume

    Science.gov (United States)

    Morales, Rudy; Peguero, Julio; Hargather, Michael

    2017-11-01

    Schlieren image velocimetry (SIV) measures velocity fields by tracking the motion of naturally-occurring turbulent flow features in a compressible flow. Here the technique is applied to measuring the exhaust velocity profile of a liquid rocket engine. The SIV measurements presented include discussion of visibility of structures, image pre-processing for structure visibility, and ability to process resulting images using commercial particle image velocimetry (PIV) codes. The small-scale liquid bipropellant rocket engine operates on nitrous oxide and ethanol as propellants. Predictions of the exhaust velocity are obtained through NASA CEA calculations and simple compressible flow relationships, which are compared against the measured SIV profiles. Analysis of shear layer turbulence along the exhaust plume edge is also presented.

  15. AUV-Based Plume Tracking: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Awantha Jayasiri

    2016-01-01

    Full Text Available This paper presents a simulation study of an autonomous underwater vehicle (AUV navigation system operating in a GPS-denied environment. The AUV navigation method makes use of underwater transponder positioning and requires only one transponder. A multirate unscented Kalman filter is used to determine the AUV orientation and position by fusing high-rate sensor data and low-rate information. The paper also proposes a gradient-based, efficient, and adaptive novel algorithm for plume boundary tracking missions. The algorithm follows a centralized approach and it includes path optimization features based on gradient information. The proposed algorithm is implemented in simulation on the AUV-based navigation system and successful boundary tracking results are obtained.

  16. Comparing plume characteristics inferred from cross-borehole geophysical data

    DEFF Research Database (Denmark)

    Haarder, Eline Bojsen; Binley, Andrew; Zibar, Majken Caroline Looms

    2012-01-01

    Three cross-borehole geophysical methods are used to image water migration in the unsaturated zone after a point injection of water. Mass balance calculations and moment analysis highlight the differences in resolution between the methods. The choice of moisture content threshold value...... significantly influences results of the moment analysis. We compare results of three cross-borehole geophysical approaches for imaging tracer migration arising from a point injection of water in the unsaturated zone: three-dimensional electrical resistivity tomography (ERT), two-dimensional ground......-penetrating radar (GPR) tomography and quasi-three-dimensional GPR tomography. In the studied field experiment, a tracer was injected for a period of 5 d and was monitored both during injection and for 5 d during the subsequent redistribution. The three methods show similar characteristics of the plume development...

  17. Space-based Observational Constraints for 1-D Plume Rise Models

    Science.gov (United States)

    Martin, Maria Val; Kahn, Ralph A.; Logan, Jennifer A.; Paguam, Ronan; Wooster, Martin; Ichoku, Charles

    2012-01-01

    We use a space-based plume height climatology derived from observations made by the Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard the NASA Terra satellite to evaluate the ability of a plume-rise model currently embedded in several atmospheric chemical transport models (CTMs) to produce accurate smoke injection heights. We initialize the plume-rise model with assimilated meteorological fields from the NASA Goddard Earth Observing System and estimated fuel moisture content at the location and time of the MISR measurements. Fire properties that drive the plume-rise model are difficult to estimate and we test the model with four estimates for active fire area and four for total heat flux, obtained using empirical data and Moderate Resolution Imaging Spectroradiometer (MODIS) re radiative power (FRP) thermal anomalies available for each MISR plume. We show that the model is not able to reproduce the plume heights observed by MISR over the range of conditions studied (maximum r2 obtained in all configurations is 0.3). The model also fails to determine which plumes are in the free troposphere (according to MISR), key information needed for atmospheric models to simulate properly smoke dispersion. We conclude that embedding a plume-rise model using currently available re constraints in large-scale atmospheric studies remains a difficult proposition. However, we demonstrate the degree to which the fire dynamical heat flux (related to active fire area and sensible heat flux), and atmospheric stability structure influence plume rise, although other factors less well constrained (e.g., entrainment) may also be significant. Using atmospheric stability conditions, MODIS FRP, and MISR plume heights, we offer some constraints on the main physical factors that drive smoke plume rise. We find that smoke plumes reaching high altitudes are characterized by higher FRP and weaker atmospheric stability conditions than those at low altitude, which tend to remain confined

  18. An idealized study of near equatorial river plumes

    Science.gov (United States)

    Palma, Elbio D.; Matano, Ricardo P.

    2017-05-01

    The dynamics of near equatorial river plumes (NERPs) are investigated using a highly idealized model. The spreading of a NERP from an eastern boundary is characterized by a continuous shedding of westward propagating eddies. This process transfers the bulk of the freshwater discharge to the deep ocean, thus distinguishing NERPs from their midlatitude counterparts. In the long-term limit, a NERP can be rationalized as a β-plume emanating from a coastal source. The evolution of NERPs in an unstratified basin is quite different from that in a stratified one. The spin-up in an unstratified basin is characterized by the formation of an anticyclonic bulge, which spreads westward thus creating a density stratification that favors the subsequent development of smaller and faster moving secondary eddies. The collision of the secondary eddies with the leading bulge arrests the effects of mixing thus allowing the further spreading of the buoyancy anomaly. In a stratified basin, the generation of anticyclonic eddies is accompanied by a concurrent generation of cyclones, which pump saltier waters to the surface hence leading to smaller sea surface salinity (SSS) anomalies. NERPs are sensitive to variations of the freshwater flux (Qfw) and the geomorphological setting. Larger Qfw generates bigger eddies, which spread at a rate proportional to the square root of the normalized flux. Wide shelves allow the interaction of the eddies with the bottom, thus promoting a cyclonic shift of the axis of the eddy train. The inclination of the coast affects the dynamical balance controlling the near-field behavior of NERPs.

  19. Satellite Remote Sensing Detection of Wastewater Plumes in Southern California

    Science.gov (United States)

    Trinh, R. C.; Holt, B.; Pan, B. J.; Rains, C.; Gierach, M. M.

    2014-12-01

    Wastewater discharged through ocean outfalls can surface near coastlines and beaches, posing a threat to the marine environment and human health. Coastal waters of the Southern California Bight (SCB) are an ecologically important marine habitat and a valuable resource in terms of commercial fishing and recreation. Two of the largest wastewater treatment plants along the U.S. West Coast discharge into the SCB, including the Hyperion Wastewater Treatment Plant (HWTP) and the Orange County Sanitation District (OCSD). In 2006, HWTP conducted an internal inspection of its primary 8 km outfall pipe (60 m depth), diverting treated effluent to a shorter 1.2 km pipe (18 m depth) from Nov. 28 to Nov. 30. From Sep. 11 - Oct. 4, 2012, OCSD conducted a similar diversion, diverting effluent from their 7 km outfall pipe to a shallower 2.2 km pipe, both with similar depths to HWTP. Prevailing oceanographic conditions in the SCB, such as temporally reduced stratification and surface circulation patterns, increased the risk of effluent being discharged from these shorter and shallower pipes surfacing and moving onshore. The aim of this study was to evaluate the capabilities of satellite remote sensing data (i.e., sea surface roughness from SAR, sea surface temperature from MODIS-Aqua and ASTER-Terra, chlorophyll-a and water leaving radiance from MODIS-Aqua) in the identification and tracking of wastewater plumes during the 2006 HWTP and 2012 OCSD diversion events. Satellite observations were combined with in situ, wind, and current data taken during the diversion events, to validate remote sensing techniques and gain surface to subsurface context of the nearshore diversion events. Overall, it was found that satellite remote sensing data were able to detect surfaced wastewater plumes along the coast, providing key spatial information that could inform in situ field sampling during future diversion events, such as the planned 2015 HWTP diversion, and thereby constrain costs.

  20. Sampling and analysis of particles from buoyant hydrothermal plumes

    Science.gov (United States)

    Mottl, Michael J.

    The objective of our studies has been to identify the chemical processes that occur in the buoyant part of hydrothermal plumes and to evaluate their role in determining the ultimate fate of the hydrothermal input to the oceans. Our first such effort is described by Mottl and McConachy [1990]. Because the buoyant plume is a small feature that contains very large physical and chemical gradients, we have sampled it from manned submersibles. We have used two different samplers, both manufactured by General Oceanics in Miami: the Go-Flo bottle and the Chopstick sampler. Four Go-Flo bottles of 1.7 L capacity can readily be mounted on most submersibles, vertically and in a forward position in sight of the pilot's viewport and video cameras, without interfering with other operations on a dive. On Alvin they have typically been mounted on the outside starboard edge of the basket. On Turtle they were mounted on the outside edge of the port manipulator. We chose Go-Flo rather than Niskin bottles because the latter are prone to spillage when the rods attached to the end caps are bumped against an object such as the seafloor, as often happens on a submersible dive. Go-Flo bottles are also more easily rigged for pressure filtration than are Niskins. The main disadvantage of Go-Flo bottles vs. Niskins for this application is the internal silicone rubber ring that holds the ball valves in place on each end of the Go-Flo. This ring tends to trap large particles that are then difficult to dislodge and collect. The rings are also difficult to clean between dives.

  1. Guided episodic sampling for capturing and characterizing industrial plumes

    Science.gov (United States)

    Ou-Yang, Chang-Feng; Liao, Wei-Cheng; Chang, Chih-Chung; Hsieh, Hsin-Cheng; Wang, Jia-Lin

    2018-02-01

    An integrated sampling technique, dubbed trigger sampling, was developed to capture characteristic industrial emissions or plumes. In the field experiment, a hydrogen sulfide (H2S) analyzer was used as the triggering instrument at the boundary of a refinery plant due to frequent complaints of foul smell from local residents. Ten episodic samples were captured when the H2S level surpassed the prescribed trigger level of 8.5 ppbv over a three-day period. Three non-episodic (blank) samples and 23 road-side samples were also collected for comparison. All the 36 flask samples were analyzed by gas chromatography-mass spectrometry/flame ionization detection (GC-MS/FID) for 108 volatile organic compounds (VOCs). The total VOC abundance of the event samples was exceedingly higher than the non-episodic samples by over 80 times in the extreme case. Alkanes were found to be the dominant constituents in the event samples, amounting to over 90% of the total VOC concentrations vs. only 30-40% for the blank and metropolitan samples. In addition, light alkanes in the event samples were highly correlated with the trigger species H2S (R2 = 0.82), implying their common origin. The matrix of chemical composition vs. sample types permitted easy visualization of the dominance of light alkanes for the event samples compared to other types of samples. Principle component analysis (PCA) identified two major contributors to cover 93% of the total variance arising from the 36 samples, further quantifying the distinction of the triggered episodic samples from the contrast samples. The proposed trigger sampling is a coupling of fast-and-slow measurement techniques. In this example, the fast-response H2S analyzer served to "guide" sampling to capture industrial plumes which were then characterized by a relatively slow method of GC-MS/FID for detailed chemical composition representative of the prominent sources.

  2. Experimental and observational evidence for plume-induced subduction on Venus

    Science.gov (United States)

    Davaille, A.; Smrekar, S. E.; Tomlinson, S.

    2017-04-01

    Why Venus lacks plate tectonics remains an unanswered question in terrestrial planet evolution. There is observational evidence for subduction--a requirement for plate tectonics--on Venus, but it is unclear why the features have characteristics of both mantle plumes and subduction zones. One explanation is that mantle plumes trigger subduction. Here we compare laboratory experiments of plume-induced subduction in a colloidal solution of nanoparticles to observations of proposed subduction sites on Venus. The experimental fluids are heated from below to produce upwelling plumes, which in turn produce tensile fractures in the lithosphere-like skin that forms on the upper surface. Plume material upwells through the fractures and spreads above the skin, analogous to volcanic flooding, and leads to bending and eventual subduction of the skin along arcuate segments. The segments are analogous to the semi-circular trenches seen at two proposed sites of plume-triggered subduction at Quetzalpetlatl and Artemis coronae. Other experimental deformation structures and subsurface density variations are also consistent with topography, radar and gravity data for Venus. Scaling analysis suggests that this regime with limited, plume-induced subduction is favoured by a hot lithosphere, such as that found on early Earth or present-day Venus.

  3. Numerical Study of Dual-Plume Interference in a Turbulent Boundary Layer

    Science.gov (United States)

    Oskouie, Shahin N.; Wang, Bing-Chen; Yee, Eugene

    2017-09-01

    Direct numerical simulation is used to investigate the interference arising from the dispersion of passive scalar plumes released from a pair of point sources in a fully-developed wall-bounded shear flow. Four different lateral separations of the two sources for both near ground-level and elevated releases are considered. The downwind evolution of the correlation between the plume concentrations along the centreline between the two sources and the behaviour of the lateral profiles of the correlation at various locations downwind of the two sources are examined in detail. Differences in the exceedance probability over a high concentration level for a single plume and the total plume are highlighted and studied, and the effects of destructive and constructive interferences on the exceedance probabilities for the total plume are used to explain these differences. One significant result is that all higher-order (third-order and above) moments of the total concentration can be inferred from the application of a clipped-gamma distribution using the information embodied in only the first- and second-order concentration moments of each single plume, and in the cross-correlation coefficient of the instantaneous concentration of the two plumes.

  4. The role of viscosity contrast on plume structure in laboratory modeling of mantle convection

    CERN Document Server

    Prakash, Vivek N; Arakeri, Jaywant H

    2016-01-01

    We have conducted laboratory experiments to model important aspects of plumes in mantle convection. We focus on the role of the viscosity ratio U (between the ambient fluid and the plume fluid) in determining the plume structure and dynamics. In our experiments, we are able to capture geophysical convection regimes relevant to mantle convection both for hot spots (when U > 1) and plate-subduction (when U < 1) regimes. The planar laser induced fluorescence (PLIF) technique is used for flow visualization and characterizing the plume structures. The convection is driven by compositional buoyancy generated by the perfusion of lighter fluid across a permeable mesh and the viscosity ratio U is systematically varied over a range from 1/300 to 2500. The planform, near the bottom boundary for U=1, exhibits a well-known dendritic line plume structure. As the value of U is increased, a progressive morphological transition is observed from the dendritic-plume structure to discrete spherical plumes, accompanied with th...

  5. Applicability of an integrated plume rise model for the dispersion from wild-land fires

    Science.gov (United States)

    Kukkonen, J.; Nikmo, J.; Sofiev, M.; Riikonen, K.; Petäjä, T.; Virkkula, A.; Levula, J.; Schobesberger, S.; Webber, D. M.

    2014-11-01

    We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model predictions with the data of two prescribed wild-land fire experiments. For the SCAR-C experiment in Quinault (US) in 1994, the predicted vertical extents of the plume at maximum plume rise were between 500 and 800 m and between 200 and 700 m, using two alternative meteorological data sets. The corresponding observed injection heights of the aerosol particles measured using an airborne lidar (light detection and ranging) ranged from 250 to 600 m. For the prescribed burning experiment in Hyytiälä (Finland) in 2009, the model predictions were compared with plume elevations and diameters, determined based on particulate matter number concentration measurements onboard an aeroplane. However, the agreement between modelled and measured results substantially depends on how the properties of the source term are evaluated, especially regarding the convective heat fluxes from the fire. The results demonstrate that in field experiments on wild-land fires, there are substantial uncertainties in estimating both (i) the source terms for the atmospheric dispersion computations and (ii) the relevant vertical meteorological profiles.

  6. Self-consistent modeling of laminar electrohydrodynamic plumes from ultra-sharp needles in cyclohexane

    Science.gov (United States)

    Becerra, Marley; Frid, Henrik; Vázquez, Pedro A.

    2017-12-01

    This paper presents a self-consistent model of electrohydrodynamic (EHD) laminar plumes produced by electron injection from ultra-sharp needle tips in cyclohexane. Since the density of electrons injected into the liquid is well described by the Fowler-Nordheim field emission theory, the injection law is not assumed. Furthermore, the generation of electrons in cyclohexane and their conversion into negative ions is included in the analysis. Detailed steady-state characteristics of EHD plumes under weak injection and space-charge limited injection are studied. It is found that the plume characteristics far from both electrodes and under weak injection can be accurately described with an asymptotic simplified solution proposed by Vazquez et al. ["Dynamics of electrohydrodynamic laminar plumes: Scaling analysis and integral model," Phys. Fluids 12, 2809 (2000)] when the correct longitudinal electric field distribution and liquid velocity radial profile are used as input. However, this asymptotic solution deviates from the self-consistently calculated plume parameters under space-charge limited injection since it neglects the radial variations of the electric field produced by a high-density charged core. In addition, no significant differences in the model estimates of the plume are found when the simulations are obtained either with the finite element method or with a diffusion-free particle method. It is shown that the model also enables the calculation of the current-voltage characteristic of EHD laminar plumes produced by electron field emission, with good agreement with measured values reported in the literature.

  7. Impact of wind on the dynamics of explosive volcanic plumes inferred from analog experiments

    Science.gov (United States)

    Carazzo, G.; Girault, F.; Aubry, T. J.; Bouquerel, H.; Kaminski, E. C.

    2014-12-01

    Volcanic plumes produced by explosive eruptions commonly interact with atmospheric wind causing plume bending and a reduction of its maximum height. Strength of the wind field and intensity of the eruption control the behavior of the column in the atmosphere, which may form either a strong plume that is little affected by the presence of wind or a weak plume that is bent-over in the wind field. To better understand the transition between weak and strong plumes, we present a series of new laboratory reproducing a buoyant jet rising in a stratified environment with a uniform cross-flow. The experiments consist in injecting downward fresh water in a tank containing an aqueous NaCl solution with linear density stratification. The jet source is towed at a constant speed through the stationary fluid in order to produce a cross-flow. We show that depending on the environmental and source conditions, the buoyant jet may form either a strong, distorted, or weak plume. The transition from one dynamical regime to another is governed by the strength of the horizontal wind velocity compared to the vertical buoyant rise of the plume. A review of field data on historical eruptions confirms that the experimentally-determined transition curves capture the behavior of volcanic columns. We quantify the impact of wind on the maximum height reached by the column, and we propose a universal scaling relationship to link the mass discharge rate feeding an eruption to its observed maximum height in the presence of wind.

  8. Uncertainty analysis of a model of wind-blown volcanic plumes.

    Science.gov (United States)

    Woodhouse, Mark J; Hogg, Andrew J; Phillips, Jeremy C; Rougier, Jonathan C

    Mathematical models of natural processes can be used as inversion tools to predict unobserved properties from measured quantities. Uncertainty in observations and model formulation impact on the efficacy of inverse modelling. We present a general methodology, history matching, that can be used to investigate the effect of observational and model uncertainty on inverse modelling studies. We demonstrate history matching on an integral model of volcanic plumes that is used to estimate source conditions from observations of the rise height of plumes during the eruptions of Eyjafjallajökull, Iceland, in 2010 and Grímsvötn, Iceland, in 2011. Sources of uncertainty are identified and quantified, and propagated through the integral plume model. A preliminary sensitivity analysis is performed to identify the uncertain model parameters that strongly influence model predictions. Model predictions are assessed against observations through an implausibility measure that rules out model inputs that are considered implausible given the quantified uncertainty. We demonstrate that the source mass flux at the volcano can be estimated from plume height observations, but the magmatic temperature, exit velocity and exsolved gas mass fraction cannot be accurately determined. Uncertainty in plume height observations and entrainment coefficients results in a large range of plausible values of the source mass flux. Our analysis shows that better constraints on entrainment coefficients for volcanic plumes and more precise observations of plume height are required to obtain tightly constrained estimates of the source mass flux.

  9. Development and experimental verification of a model for an air jet penetrated by plumes

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2015-03-01

    Full Text Available This article presents the fluid mechanics of a ventilation system formed by a momentum source and buoyancy sources. We investigate the interaction between plumes and a non-isothermal air jet for separate sources of buoyancy produced by the plume and the momentum of the air jet. The mathematical model represents the situation in which a plume rises from two heat sources causing buoyancy. The model is used to discuss the interactions involved. The effects of parameters such as the power of the source and the air-flow volume used in the mathematical-physical model are also discussed. An expression is deduced for the trajectory of the non-isothermal air jet penetrated by plumes. Experiments were also carried out to illustrate the effect on the flow of the air jet and to validate the theoretical work. The results show that the buoyancy source’s efforts to baffle the descent of the cold air have even been effective in reversing the direction of the trajectory. However, increasing the distance between the plumes can reduce the effect of the plumes on the jet curve. And it is apparent that when the velocity of the air supply increases, the interference caused by the plumes can be reduced.

  10. Beyond the vent: New perspectives on hydrothermal plumes and pelagic biology

    Science.gov (United States)

    Phillips, Brennan T.

    2017-03-01

    Submarine hydrothermal vent fields introduce buoyant plumes of chemically altered seawater to the deep-sea water column. Chemoautotrophic microbes exploit this energy source, facilitating seafloor-based primary production that evidence suggests may transfer to pelagic consumers. While most hydrothermal plumes have relatively small volumes, there are recent examples of large-scale plume events associated with periods of eruptive activity, which have had a pronounced effect on water-column biology. This correlation suggests that hydrothermal plumes may have influenced basin-scale ocean chemistry during periods of increased submarine volcanism during the Phanerozoic eon. This paper synthesizes a growing body of scientific evidence supporting the hypothesis that hydrothermal plumes are the energetic basis of unique deep-sea pelagic food webs. While many important questions remain concerning the biology of hydrothermal plumes, this discussion is not present in ongoing management efforts related to seafloor massive sulfide (SMS) mining. Increased research efforts, focused on high-resolution surveys of midwater biology relative to plume structures, are recommended to establish baseline conditions and monitor the impact of future mining-based disturbances to the pelagic biosphere.

  11. Automated recognition and tracking of aerosol threat plumes with an IR camera pod

    Science.gov (United States)

    Fauth, Ryan; Powell, Christopher; Gruber, Thomas; Clapp, Dan

    2012-06-01

    Protection of fixed sites from chemical, biological, or radiological aerosol plume attacks depends on early warning so that there is time to take mitigating actions. Early warning requires continuous, autonomous, and rapid coverage of large surrounding areas; however, this must be done at an affordable cost. Once a potential threat plume is detected though, a different type of sensor (e.g., a more expensive, slower sensor) may be cued for identification purposes, but the problem is to quickly identify all of the potential threats around the fixed site of interest. To address this problem of low cost, persistent, wide area surveillance, an IR camera pod and multi-image stitching and processing algorithms have been developed for automatic recognition and tracking of aerosol plumes. A rugged, modular, static pod design, which accommodates as many as four micro-bolometer IR cameras for 45deg to 180deg of azimuth coverage, is presented. Various OpenCV1 based image-processing algorithms, including stitching of multiple adjacent FOVs, recognition of aerosol plume objects, and the tracking of aerosol plumes, are presented using process block diagrams and sample field test results, including chemical and biological simulant plumes. Methods for dealing with the background removal, brightness equalization between images, and focus quality for optimal plume tracking are also discussed.

  12. Space Shuttle main engine OPAD: The search for a hardware enhanced plume

    Science.gov (United States)

    Powers, W. T.; Cooper, A. E.; Wallace, Tim L.; Buntine, W. L.; Whitaker, K. W.

    1993-01-01

    The process of applying spectroscopy to the Space Shuttle Main Engine (SSME) for plume diagnostics, as it exists today, originated at Marshall Space Flight Center in Huntsville, Alabama, and its implementation was assured largely through the efforts of Sverdrup AEDC, in Tullahoma, Tennessee. This team continues to lead and guide efforts in the plume diagnostics arena. The process, Optical Plume Anomaly Detection (OPAD), formed the basis for various activities in the development of ground-based systems as well as the development of in-flight plume spectroscopy. OPAD currently provides and will continue to provide valuable information relative to future systems definitions, instrumentation development, code validation, and data diagnostic processing. OPAD is based on the detection of anomalous atomic and molecular species in the SSME plume using two complete, stand-alone optical spectrometers. To-date OPAD has acquired data on 44 test firings of the SSME at the Technology Test Bed (TTB) at MSFC. The purpose of this paper will be to provide an introduction to the OPAD system by discussing the process of obtaining data as well as the methods of examining and interpreting the data. It will encompass such issues as selection of instrumentation correlation of data to nominal engine operation, investigation of SSME component erosion via OPAD spectral data, necessity and benefits of plume seeding, application of artificial intelligence (AI) techniques to data analysis, and the present status of efforts to quantify specie erosion utilizing standard plume and chemistry codes as well as radiative models currently under development.

  13. Shock Wave Mediated Plume Chemistry for Molecular Formation in Laser Ablation Plasmas.

    Science.gov (United States)

    Harilal, Sivanandan S; Brumfield, Brian E; Cannon, Bret D; Phillips, Mark C

    2016-02-16

    Although it is relatively straightforward to measure the ionic, atomic, molecular, and particle emission features from laser ablation plumes, the associated kinetic and thermodynamic development leading to molecular and nanocluster formation remain one of the most important topics of analytical chemistry and material science. Very little is known, for instance, about the evolutionary paths of molecular and nanocluster formation and its relation to laser plume hydrodynamics. This is, to a large extent; due to the complexity of numerous physical processes that coexist in a transient laser-plasma system. Here, we report the formation mechanisms of molecules during complex interactions of a laser-produced plasma plume expanding from a high purity aluminum metal target into ambient air. It is found that the plume hydrodynamics plays a great role in redefining the plasma thermodynamics and molecular formation. Early in the plasma expansion, the generated shock wave at the plume edge acts as a barrier for the combustion process and molecular formation is prevalent after the shock wave collapse. The temporally and spatially resolved contour mapping of atoms and molecules in laser ablation plumes highlight the formation routes and persistence of species in the plasma and their relation to plume hydrodynamics.

  14. Experimental and computational study of complex shockwave dynamics in laser ablation plumes in argon atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, S. S.; Miloshevsky, G. V.; Diwakar, P. K.; LaHaye, N. L.; Hassanein, A. [Center for Materials under Extreme Environment, and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2012-08-15

    We investigated spatio-temporal evolution of ns laser ablation plumes at atmospheric pressure, a favored condition for laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass-spectrometry. The 1064 nm, 6 ns pulses from a Nd:YAG laser were focused on to an Al target and the generated plasma was allowed to expand in 1 atm Ar. The hydrodynamic expansion features were studied using focused shadowgraphy and gated 2 ns self-emission visible imaging. Shadowgram images showed material ejection and generation of shock fronts. A secondary shock is observed behind the primary shock during the time window of 100-500 ns with instabilities near the laser cone angle. By comparing the self-emission images obtained using fast photography, it is concluded that the secondary shocks observed in the shadowgraphy were generated by fast moving target material. The plume front estimates using fast photography exhibited reasonable agreement with data obtained from shadowgraphy at early times {<=}400 ns. However, at later times, fast photography images showed plume confinement while the shadowgraphic images showed propagation of the plume front even at greater times. The structure and dynamics of the plume obtained from optical diagnostic tools were compared to numerical simulations. We have shown that the main features of plume expansion in ambient Ar observed in the experiments can be reproduced using a continuum hydrodynamics model which provided valuable insight into the expansion dynamics and shock structure of the plasma plume.

  15. Experimental and computational study of complex shockwave dynamics in laser ablation plumes in argon atmosphere

    Science.gov (United States)

    Harilal, S. S.; Miloshevsky, G. V.; Diwakar, P. K.; LaHaye, N. L.; Hassanein, A.

    2012-08-01

    We investigated spatio-temporal evolution of ns laser ablation plumes at atmospheric pressure, a favored condition for laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass-spectrometry. The 1064 nm, 6 ns pulses from a Nd:YAG laser were focused on to an Al target and the generated plasma was allowed to expand in 1 atm Ar. The hydrodynamic expansion features were studied using focused shadowgraphy and gated 2 ns self-emission visible imaging. Shadowgram images showed material ejection and generation of shock fronts. A secondary shock is observed behind the primary shock during the time window of 100-500 ns with instabilities near the laser cone angle. By comparing the self-emission images obtained using fast photography, it is concluded that the secondary shocks observed in the shadowgraphy were generated by fast moving target material. The plume front estimates using fast photography exhibited reasonable agreement with data obtained from shadowgraphy at early times ≤400 ns. However, at later times, fast photography images showed plume confinement while the shadowgraphic images showed propagation of the plume front even at greater times. The structure and dynamics of the plume obtained from optical diagnostic tools were compared to numerical simulations. We have shown that the main features of plume expansion in ambient Ar observed in the experiments can be reproduced using a continuum hydrodynamics model which provided valuable insight into the expansion dynamics and shock structure of the plasma plume.

  16. The importance of plume rise on the concentrations and atmospheric impacts of biomass burning aerosol

    Directory of Open Access Journals (Sweden)

    C. Walter

    2016-07-01

    Full Text Available We quantified the effects of the plume rise of biomass burning aerosol and gases for the forest fires that occurred in Saskatchewan, Canada, in July 2010. For this purpose, simulations with different assumptions regarding the plume rise and the vertical distribution of the emissions were conducted. Based on comparisons with observations, applying a one-dimensional plume rise model to predict the injection layer in combination with a parametrization of the vertical distribution of the emissions outperforms approaches in which the plume heights are initially predefined. Approximately 30 % of the fires exceed the height of 2 km with a maximum height of 8.6 km. Using this plume rise model, comparisons with satellite images in the visible spectral range show a very good agreement between the simulated and observed spatial distributions of the biomass burning plume. The simulated aerosol optical depth (AOD with data of an AERONET station is in good agreement with respect to the absolute values and the timing of the maximum. Comparison of the vertical distribution of the biomass burning aerosol with CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation retrievals also showed the best agreement when the plume rise model was applied. We found that downwelling surface short-wave radiation below the forest fire plume is reduced by up to 50 % and that the 2 m temperature is decreased by up to 6 K. In addition, we simulated a strong change in atmospheric stability within the biomass burning plume.

  17. Dynamics and Significance of Plume-Induced Subduction Initiation: Numerical Modeling

    Science.gov (United States)

    Gerya, T.; Stern, R. J.; Baes, M.; Sobolev, S. V.; Whattam, S. A.

    2014-12-01

    How did the first subduction zone form? Most present-day subduction initiation mechanisms require acting plate forces and/or preexisting zones of lithospheric weakness, which are themselves the consequence of plate tectonics (Stern 2004). In contrast, spontaneous plume-induced subduction initiation - suggested on the basis of numerical thermo-mechanical experiments (Ueda et al., 2008) and supported by data re-interpretation of how subduction started in Late Cretaceous time around the Caribbean LIP (Whattam and Stern, 2014) - does not require pre-existing lithospheric fabric, such as are created by active plate tectonics and is viable for both stagnant lid and mobile/deformable lid conditions. Here, we present first results of high-resolution 3D numerical thermo-mechanical modeling of plume-induced subduction resulting from mechanical-magmatic interaction of an ascending thermal mantle plume with old, cold, dense oceanic lithosphere. We demonstrate that weakening of the strong lithosphere by plume-induced magmatism is the key factor enabling subduction initiation around the plume head. A large plume head is required to overcome ring confinement, and subduction initiation is further favored when plume activity and lithospheric weakening continues for several tens of Ma. We further discuss possible implications of this scenario for modern plate tectonics as well as for plate tectonics initiation in Precambrian time. ReferencesStern, R.J., 2004. Subduction initiation: spontaneous and induced. EPSL 226, 275-292.Ueda, K., Gerya, T., Sobolev, S.V., 2008. Subduction initiation by thermal-chemical plumes. PEPI 171, 296-312.Whattam, S.A., Stern, R. 2014. Late Cretaceous plume-induced subduction initiation along the southern margin of the Caribbean and NW South America: The first documented example with implications for the onset of plate tectonics. Gondwana Research, (accepted).

  18. Mass discharge in a tracer plume: evaluation of the Theissen Polygon Method.

    Science.gov (United States)

    Mackay, Douglas M; Einarson, Murray D; Kaiser, Phil M; Nozawa-Inoue, Mamie; Goyal, Sham; Chakraborty, Irina; Rasa, Ehsan; Scow, Kate M

    2012-01-01

    A tracer plume was created within a thin aquifer by injection for 299 d of two adjacent "sub-plumes" to represent one type of plume heterogeneity encountered in practice. The plume was monitored by snapshot sampling of transects of fully screened wells. The mass injection rate and total mass injected were known. Using all wells in each transect (0.77 m well spacing, 1.4 points/m(2) sampling density), the Theissen Polygon Method (TPM) yielded apparently accurate mass discharge (M(d) ) estimates at three transects for 12 snapshots. When applied to hypothetical sparser transects using subsets of the wells with average spacing and sampling density from 1.55 to 5.39 m and 0.70 to 0.20 points/m(2) , respectively, the TPM accuracy depended on well spacing and location of the wells in the hypothesized transect with respect to the sub-plumes. Potential error was relatively low when the well spacing was less than the widths of the sub-plumes (>0.35 points/m(2) ). Potential error increased for well spacing similar to or greater than the sub-plume widths, or when less than 1% of the plume area was sampled. For low density sampling of laterally heterogeneous plumes, small changes in groundwater flow direction can lead to wide fluctuations in M(d) estimates by the TPM. However, sampling conducted when flow is known or likely to be in a preferred direction can potentially allow more useful comparisons of M(d) over multiyear time frames, such as required for performance evaluation of natural attenuation or engineered remediation systems. © 2012, The Author(s). Ground Water © 2012, National Ground Water Association.

  19. Influence of a West Antarctic mantle plume on ice sheet basal conditions

    Science.gov (United States)

    Seroussi, Helene; Ivins, Erik R.; Wiens, Douglas A.; Bondzio, Johannes

    2017-09-01

    The possibility that a deep mantle plume manifests Pliocene and Quaternary volcanism and potential elevated heat flux in West Antarctica has been studied for more than 30 years. Recent seismic images support the plume hypothesis as the cause of Marie Byrd Land (MBL) volcanism and geophysical structure. Mantle plumes may more than double the geothermal heat flux above nominal continental values. A dearth of in situ ice sheet basal data exists that samples the heat flux. Consequently, we examine a realistic distribution of heat flux associated with a possible late Cenozoic mantle plume in West Antarctica and explore its impact on thermal and melt conditions at the ice sheet base. We use a simple analytical mantle plume parameterization to produce geothermal heat flux at the base of the ice sheet. The three-dimensional ice flow model includes an enthalpy framework and full-Stokes stress balance. As both the putative plume location and extent are uncertain, we perform broadly scoped experiments to characterize the impact of the plume on geothermal heat flux and ice sheet basal conditions. The experiments show that mantle plumes have an important local impact on the ice sheet, with basal melting rates reaching several centimeters per year directly above the hotspot. In order to be consistent with observations of basal hydrology in MBL, the upper bound on the plume-derived geothermal heat flux is 150 mW/m2. In contrast, the active lake system of the lower part of Whillans Ice Stream suggests a widespread anomalous mantle heat flux, linked to a rift source.

  20. Determining volcanic SO2 plume heights in satellite observations using meteorological wind fields

    Science.gov (United States)

    Keicher, Viktoria; Hörmann, Christoph; Sihler, Holger; Platt, Ulrich; Wagner, Thomas

    2016-04-01

    Satellite observations nowadays provide the global monitoring of volcanic plumes via sulphur dioxide (SO2) that is injected into the Earth's atmosphere. In turn, SO2 may lead to the formation of sulphate aerosols that can influence climate via direct and indirect radiative effects. The retrieval of SO2 requires an accurate plume height estimate in order to constrain total amounts for such events. One of the main difficulties for the retrieval is the typically unknown atmospheric profile resulting from unknown initial conditions (individual explosions over an extended time period leading to different gas layer altitudes and influencing the atmospheric transport pattern). In recent years, satellite observations helped to improve global SO2 estimates, but still large uncertainties exist. Passive satellite remote sensing using measurements in the UV/vis spectral range for example offers the opportunity to observe the location of a plume in two dimensions, but information about the corresponding height is sparse. Furthermore, information about these plume profiles is not only interesting in itself (e.g. to assess the radiative effect of volcanic plumes). It is also important for the quantitative interpretation of satellite observations. Here, we present first results for a newly developed approach using the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) in combination with data for different volcanic SO2 plumes as observed by the second generation Global Ozone Monitoring Instrument (GOME-2). The main plume information that can be retrieved by the satellite (i.e. plume location and observation time) are used as initial input parameters in order to estimate the plume's profile at the time of the measurements. For selected case studies we use these trajectories to further estimate values the eruption time and height. The correspondingly modelled values can also be used to verify the results when they are compared to direct local observations and

  1. The Hainan Lone Plume Prompted By Encircling Subduction Zones around the South China Sea

    Science.gov (United States)

    Zhang, N.; Li, Z. X.

    2016-12-01

    The present of the late Mesozoic Hainan plume originated from the lower mantle of northern South China Sea has been documented by both seismic tomographic and geochemical-petrological work. The Hainan plume is one of the rare mantle plumes that are located away from the two large low shear velocity provinces (LLSVPs) in the lower mantle. Instead, it is within the broad global mantle downwelling zone, thus classified as a "lone plume". It had previously been proposed that this plume could have been triggered by subducting slabs into the lower mantle in the regions surrounding the South China Sea, a mechanism similar to what had been proposed for the formation of the LLSVPs. Here, we investigate the feasibility of such a plume-generation mechanism use a geodynamic modelling. Our geodynamic model has a high resolution regional domain embedded in a relatively low resolution global domain, which is set up in an adoptive-mesh-refined, 3D mantle convection code ASPECT. The top mechanic boundary condition of the global domain uses the latest plate motion reconstruction. In a series of experiments, we explore the effects of various important mantle parameters on mantle plume generation. The results so far suggest that the Indo-Australian cold slab acted like a cold wall from the southwest side in the present-day South China Sea mantle domain since 80 Ma ago. Fossil slabs from much older Tethyan subduction systems plays a moderate role in blocking the deep mantle hot materials from escaping to the north. The Western Pacific subduction systems started to promote the initiation of Hainan plume some 50 Ma ago from near the core-mantle boundary (CMB). As the plume head rises, it first moved to the west, and finally to beneath the South China Sea. Our model results are not sensitive to whether there is a chemical layer (possible D" layer) near the CMB.

  2. Hydrogen chloride heterogeneous chemistry on frozen water particles in subsonic aircraft plume. Laboratory studies and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Persiantseva, N.V.; Popovitcheva, O.B.; Rakhimova, T.V. [Moscow State Univ. (Russian Federation)

    1997-12-31

    Heterogeneous chemistry of HCl, as a main reservoir of chlorine content gases, has been considered after plume cooling and ice particle formation. The HCl, HNO{sub 3}, N{sub 2}O{sub 5} uptake efficiencies by frozen water were obtained in a Knudsen-cell flow reactor at the subsonic cruise conditions. The formation of ice particles in the plume of subsonic aircraft is simulated to describe the kinetics of gaseous HCl loss due to heterogeneous processes. It is shown that the HCl uptake by frozen water particles may play an important role in the gaseous HCl depletion in the aircraft plume. (author) 14 refs.

  3. Non-equilibrium radiation from viscous chemically reacting two-phase exhaust plumes

    Science.gov (United States)

    Penny, M. M.; Smith, S. D.; Mikatarian, R. R.; Ring, L. R.; Anderson, P. G.

    1976-01-01

    A knowledge of the structure of the rocket exhaust plumes is necessary to solve problems involving plume signatures, base heating, plume/surface interactions, etc. An algorithm is presented which treats the viscous flow of multiphase chemically reacting fluids in a two-dimensional or axisymmetric supersonic flow field. The gas-particle flow solution is fully coupled with the chemical kinetics calculated using an implicit scheme to calculate chemical production rates. Viscous effects include chemical species diffusion with the viscosity coefficient calculated using a two-equation turbulent kinetic energy model.

  4. Is papillomavirus detectable in the plume of laser-treated laryngeal papilloma

    Energy Technology Data Exchange (ETDEWEB)

    Abramson, A.L.; DiLorenzo, T.P.; Steinberg, B.M. (Long Island Jewish Medical Center, New Hyde Park, NY (USA))

    1990-05-01

    The carbon dioxide laser is widely used for the vaporization of lesions in patients with laryngeal papillomatosis. In this study, the smoke plume resulting from the laser treatment of laryngeal papillomas was analyzed for the presence of human papillomavirus DNA. Plumes were collected with a suction tip and trapped in phosphate-buffered saline. The aspirates were then analyzed for the presence of human papillomavirus DNA by Southern blot hybridization. Human papillomavirus DNA cannot be detected in the smoke plume from vaporization of laryngeal papillomas unless direct suction contact is made with the papilloma tissue during surgery. The implications of these findings are discussed.

  5. OPAD through 1991 - Status report no. 2. [Optical Plume Anomaly Detection

    Science.gov (United States)

    Powers, W. T.; Cooper, A. E.; Wallace, T. L.

    1991-01-01

    The Optical Plume Anomaly Detection (OPAD) experimental program has attempted to develop a rocket engine health monitor for the detection, and if possible the quantification, of anomalous atomic and molecular species in exhaust plumes. The test program has formulated instrument designs allowing both wide spectral range and high spectral resolution. Attention is presently given to OPAD data collected for the SSME at NASA-Marshall's technology test stand, with a view to spectral emissions at startup and variations in baseline plume emissions due to changes in rated power level.

  6. Characterization of Iberian turbid plumes by means of synoptic patterns obtained through MODIS imagery

    Science.gov (United States)

    Fernández-Nóvoa, D.; deCastro, M.; Des, M.; Costoya, X.; Mendes, R.; Gómez-Gesteira, M.

    2017-08-01

    Turbid plumes formed by the main Iberian rivers were analyzed and compared in order to determine similarities and differences among them. Five Atlantic rivers (Minho, Douro, Tagus, Guadiana and Guadalquivir) and one Mediterranean river (Ebro) were considered. Plume extension and turbidity were evaluated through synoptic patterns obtained by means of MODIS imagery over the period 2003-2014. River discharge showed to be the main forcing. In fact, the dependence of plume extension on runoff is moderate or high for all rivers, except for Ebro. In addition, most of river plumes adjust immediately to runoff fluctuations. Only the extension of Tagus and Guadalquivir plumes is lagged with respect to river runoff, due to the high residence time generated by their large estuaries. Wind is a secondary forcing, being only noticeable under high discharges. Actually, the dependence of plume extension on wind is moderate or high for all rivers, except Guadalquivir and Ebro. All the Atlantic rivers show the maximum (minimum) near- field plume extension under landward (oceanward) cross-shore winds. The opposite situation was observed for Ebro River. Tide is also a secondary forcing although less important than wind. Actually, the dependence of plume extension on tide is only high for Guadiana River. Nevertheless, all Atlantic river plumes still have some dependence on semidiurnal tidal cycle, they increase under low tides and decrease under high tides. In addition, Tagus River plume also depends on the fortnightly tidal cycle being larger during spring tides than during neap tides. This is due to particular shape of the estuary, where the river debouches into a semi-enclosed embayment connected to the Atlantic Ocean through a strait. Ebro River constitutes a particular case since it has a low dependence on runoff and wind and a negligible dependence on tide. In fact, its plume is mainly driven by the Liguro-Provençal coastal current. Guadalquivir River also shows some unique

  7. Modelling of transport and biogeochemical processes in pollution plumes: Vejen landfill, Denmark

    DEFF Research Database (Denmark)

    Brun, A.; Engesgaard, Peter Knudegaard; Christensen, Thomas Højlund

    2002-01-01

    A biogeochemical transport code is used to simulate leachate attenuation. biogeochemical processes. and development of redox zones in a pollution plume downstream of the Vejen landfill in Denmark. Calibration of the degradation parameters resulted in a good agreement with the observed distribution...... in the plume of a number of species. such as dissolved organic carbon (DOC), Fe2+, NO3-, HCO3-, SO42-, CH4, and pH. The simulated redox zones agree with observations confirming that the Fe-reducing zone played an important role in the attenuation of the DOC plume. Effective first-order rate constants for every...

  8. Modeling Multiple-Core Updraft Plume Rise for an Aerial Ignition Prescribed Burn by Coupling Daysmoke with a Cellular Automata Fire Model

    Science.gov (United States)

    G. L Achtemeier; S. L. Goodrick; Y. Liu

    2012-01-01

    Smoke plume rise is critically dependent on plume updraft structure. Smoke plumes from landscape burns (forest and agricultural burns) are typically structured into “sub-plumes” or multiple-core updrafts with the number of updraft cores depending on characteristics of the landscape, fire, fuels, and weather. The number of updraft cores determines the efficiency of...

  9. Relating plume spread to meteorology in urban areas

    Science.gov (United States)

    Venkatram, Akula; Isakov, Vlad; Pankratz, David; Yuan, Jing

    2005-01-01

    This paper examines relationships between dispersion and meteorology measured in a field study conducted in Barrio Logan, a suburb of San Diego, during 5 days of the period 21 August 2001-31 August 2001. The mean building height in Barrio Logan is about 4 m. The tracer, SF6, was released at a height of 5 m from a shipyard on the shoreline, and the concentrations of the tracer were sampled on 4 arcs at 200, 500, 1000, and 2000 m from the source during ten hours of the day starting at 10 am. The meteorological conditions that governed dispersion were measured using sonic anemometers and a SODAR with a range of 200 m in the vertical. It turned out that ground-level concentrations at the receptors used in this study were governed by the meteorological variables in the urban boundary layer above the urban roughness sublayer (RSL). In this region between 15 and 150 m above ground-level, the horizontal and vertical turbulent intensities were relatively uniform. This uniformity in turbulent intensities allowed the formulation of simple expressions for horizontal and vertical plume spreads that could be used in a Gaussian dispersion model. These expressions are similar to those proposed by Briggs (ERL, ARL USAEC Report ATDL-106, U.S. Atomic Energy Commission Oak Ridge, Tennessee, 1975) and Hanna et al. (Atmos. Environ. 37 (2003) 5069) to model dispersion in St. Louis and Salt Lake City, respectively. However, the application of these dispersion curves requires information on the meteorology of the boundary layer. It might be possible to use measurements above the average building height (4 m in our case) to infer these boundary layer properties. The dispersion model based on boundary layer meteorological information explained about 63% of the variance of the maximum observed concentrations on each sampling arc, and 60% of these concentrations was within a factor of two of the corresponding model estimates. It was necessary to account for initial plume spread caused by

  10. Plumes, Hotspot & Slabs Imaged by Global Adjoint Tomography

    Science.gov (United States)

    Bozdag, E.; Lefebvre, M. P.; Lei, W.; Peter, D. B.; Smith, J. A.; Komatitsch, D.; Tromp, J.

    2015-12-01

    We present the "first generation" global adjoint tomography model based on 3D wave simulations, which is the result of 15 conjugate-gradient iterations with confined transverse isotropy to the upper mantle. Our starting model is the 3D mantle and crustal models S362ANI (Kustowski et al. 2008) and Crust2.0 (Bassin et al. 2000), respectively. We take into account the full nonlinearity of wave propagation in numerical simulations including attenuation (both in forward and adjoint simulations), topography/bathymetry, etc., using the GPU version of the SPECFEM3D_GLOBE package. We invert for crust and mantle together without crustal corrections to avoid any bias in mantle structure. We started with an initial selection of 253 global CMT events within the magnitude range 5.8 ≤ Mw ≤ 7.0 with numerical simulations having resolution down to 27 s combining 30-s body and 60-s surface waves. After the 12th iteration we increased the resolution to 17 s, including higher-frequency body waves as well as going down to 45 s in surface-wave measurements. We run 180-min seismograms and assimilate all minor- and major-arc body and surface waves. Our 15th iteration model update shows a tantalisingly enhanced image of the Tahiti plume as well as various other plumes and hotspots, such as Caroline, Galapagos, Yellowstone, Erebus, etc. Furthermore, we see clear improvements in slab resolution along the Hellenic and Japan Arcs, as well as subduction along the East of Scotia Plate, which does not exist in the initial model. Point-spread function tests (Fichtner & Trampert 2011) suggest that we are close to the resolution of continental-scale studies in our global inversions and able to confidently map features, for instance, at the scale of the Yellowstone hotspot. This is a clear consequence of our multi-scale smoothing strategy, in which we define our smoothing operator as a function of the approximate Hessian kernel and smooth our gradients less wherever we have good ray coverage

  11. The EtnaPlumeLab (EPL research cluster: advance the understanding of Mt. Etna plume, from source characterisation to downwind impact

    Directory of Open Access Journals (Sweden)

    Pasquale Sellitto

    2017-01-01

    Full Text Available In 2013, a multidisciplinary research cluster named EtnaPlumeLab (EPL was established, gathering experts from volcanology and atmospheric science communities. Target of EPL is to advance the understanding of Mt. Etna's gas and aerosol emissions and the related processes, from source to its regional climatic impact in the Mediterranean area. Here, we present the cluster and its three interacting modules: EPL-RADIO (Radioactive Aerosols and other source parameters for better atmospheric Dispersion and Impact estimatiOns, SMED (Sulfur MEditerranean Dispersion and Med-SuV (MEDiterranean SUpersite Volcanoes Work Package 5. Preliminary results have for the first time highlighted the relevance of Mt. Etna's plume impact at the Mediterranean regional scale. These results underline that further efforts need to be made to get insight into a synoptic volcanogenic-atmospheric chemistry/climatic understanding of volcanic plumes impact.

  12. FOOTPRINT: A Screening Model for Estimating the Area of a Plume Produced From Gasoline Containing Ethanol

    Science.gov (United States)

    FOOTPRINT is a screening model used to estimate the length and surface area of benzene, toluene, ethylbenzene, and xylene (BTEX) plumes in groundwater, produced from a gasoline spill that contains ethanol.

  13. Transverse hydrodynamic dispersion effects on isotope signals in groundwater chlorinated solvents’ plumes.

    NARCIS (Netherlands)

    van Breukelen, B.M.; Rolle, M.

    2012-01-01

    The effects of transverse hydrodynamic dispersion on altering transformation-induced compound-specific isotope analysis (CSIA) signals within groundwater pollution plumes have been assessed with reactive transport modeling accommodating diffusion-induced isotope fractionation (DIF) and implementing

  14. Sub-microsecond vapor plume dynamics under different keyhole penetration regimes in deep penetration laser welding

    Science.gov (United States)

    Chen, Xin; Pang, Shengyong; Shao, Xinyu; Wang, Chunming; Zhang, Xiaosi; Jiang, Ping; Xiao, Jianzhong

    2017-05-01

    It is well-known that distinct vapor plume dynamics occur during deep penetration laser welding under different keyhole penetration states. However, there is little knowledge about the physical characteristics of vapor plumes (velocity, pressure, flow patterns, etc) located inside transient keyholes of varying penetration regimes in laser welding. This lack of knowledge is primarily because mesoscale vapor plumes are highly dynamic and generally invisible. Based on a well-tested three-dimensional multiphase laser welding model, we conducted a computational study on vapor plume dynamics inside transient keyholes during the fiber laser welding of 304 austenite stainless steel as a function of keyhole penetration regimes. We observed three keyhole regimes of penetration: full penetration, partial penetration and no penetration. We then physically analyzed the vapor plumes in these regimes. We determined that the vapor plume velocities and pressures in all three regimes were uneven and oscillated following the dynamic keyhole with a characteristic timescale in sub-microseconds. Only when the keyhole approached the full penetration regime did vapor plumes begin to violently eject from the bottom of the keyhole opening, whereas in the partial penetration regime, even when the bottom part of the keyhole was open, most of the vapor plume ejected from the upper keyhole opening. This latter observation was similar to that in the no penetration mode. We studied the physical mechanism of this behavior by analyzing the keyhole temperature and vapor plume velocity distributions. We determined that the upward ejection of the vapor plume from the upper keyhole opening was the result of an uneven micro-meter scale boiling phenomenon of the transient keyhole governed by Fresnel absorptions dependent on the local inclination angle of the keyhole wall. Similarly, we determined that the ejection of the vapor plume from the bottom of the keyhole opening resulted from pressure

  15. Plume fragmentation by bulk interactions in turbulent Rayleigh-Bénard convection.

    Science.gov (United States)

    Bosbach, Johannes; Weiss, Stephan; Ahlers, Guenter

    2012-02-03

    Using compressed gases with Prandtl numbers near 0.7, we obtained flow visualizations of turbulent Rayleigh-Bénard convection in a cylindrical sample with an aspect ratio Γ≡D/L≅10 (D is the diameter and L the height) by the shadowgraph method. Focusing on the plumes under the top plate, we found that their length had a log-normal distribution, suggesting a fragmentation process. Fragmentation events could be visually identified in the images and involved plume interactions with bulk fluctuations or upwelling domain walls. We found the mean spacing between plumes to vary with the Rayleigh number in proportion to the volume-averaged Kolmogorov length of the turbulent bulk fluctuations, providing further evidence for plume-bulk interactions.

  16. Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes.

    Science.gov (United States)

    Waite, J Hunter; Glein, Christopher R; Perryman, Rebecca S; Teolis, Ben D; Magee, Brian A; Miller, Greg; Grimes, Jacob; Perry, Mark E; Miller, Kelly E; Bouquet, Alexis; Lunine, Jonathan I; Brockwell, Tim; Bolton, Scott J

    2017-04-14

    Saturn's moon Enceladus has an ice-covered ocean; a plume of material erupts from cracks in the ice. The plume contains chemical signatures of water-rock interaction between the ocean and a rocky core. We used the Ion Neutral Mass Spectrometer onboard the Cassini spacecraft to detect molecular hydrogen in the plume. By using the instrument's open-source mode, background processes of hydrogen production in the instrument were minimized and quantified, enabling the identification of a statistically significant signal of hydrogen native to Enceladus. We find that the most plausible source of this hydrogen is ongoing hydrothermal reactions of rock containing reduced minerals and organic materials. The relatively high hydrogen abundance in the plume signals thermodynamic disequilibrium that favors the formation of methane from CO 2 in Enceladus' ocean. Copyright © 2017, American Association for the Advancement of Science.

  17. Rise and Collapse of Volcanic Plumes Produced By Explosive Basaltic Fissure Eruptions

    Science.gov (United States)

    Paillat, S.; Kaminski, E. C.

    2014-12-01

    Explosive basaltic fissure eruptions, which release large amounts of sulfur gases in the atmosphere, can have a big impact on climate. The effect on climate depends on the rate of gas injection above the tropopause. The key parameter is the height reached by the eruptive plume as a function of mass flux and entrainment rate. We propose a model of entrainment in 2D volcanic plumes based on lab scale experiments on turbulent jets and plumes. In this model, entrainment varies with the Richardson number and we predict that the height of the column critically depends on the source buoyancy flux determined by the eruptive temperature and the amount of gas in the volcanic mixture at the vent. We obtain that "hot" basaltic planar plumes form stable eruptive columns, even for large eruption rates. Only if fragmentation is not efficient enough, the column collapse will prevent the injection of gas in the stratosphere.

  18. Fractal analysis: A new tool in transient volcanic ash plume characterization.

    Science.gov (United States)

    Tournigand, Pierre-Yves; Peña Fernandez, Juan Jose; Taddeucci, Jacopo; Perugini, Diego; Sesterhenn, Jörn

    2017-04-01

    Transient volcanic plumes are time-dependent features generated by unstable eruptive sources. They represent a threat to human health and infrastructures, and a challenge to characterize due to their intrinsic instability. Plumes have been investigated through physical (e.g. visible, thermal, UV, radar imagery), experimental and numerical studies in order to provide new insights about their dynamics and better anticipate their behavior. It has been shown experimentally that plume dynamics is strongly dependent to source conditions and that plume shape evolution holds key to retrieve these conditions. In this study, a shape evolution analysis is performed on thermal high-speed videos of volcanic plumes from three different volcanoes Sakurajima (Japan), Stromboli (Italy) and Fuego (Guatemala), recorded with a FLIR SC655 thermal camera during several field campaigns between 2012 and 2016. To complete this dataset, three numerical gas-jet simulations at different Reynolds number (2000, 5000 and 10000) have been used in order to set reference values to the natural cases. Turbulent flow shapes are well known to feature scale-invariant structures and a high degree of complexity. For this reason we characterized the bi-dimensional shape of natural and synthetic plumes by using a fractal descriptor. Such method has been applied in other studies on experimental turbulent jets as well as on atmospheric clouds and have shown promising results. At each time-step plume contour has been manually outlined and measured using the box-counting method. This method consists in covering the image with squares of variable sizes and counting the number of squares containing the plume outline. The negative slope of the number of squares in function of their size in a log-log plot gives the fractal dimension of the plume at a given time. Preliminary results show an increase over time of the fractal dimension for natural volcanic plume as well as for the numerically simulated ones, but at

  19. Crude oil jets in crossflow: Effects of dispersant concentration on plume behavior

    National Research Council Canada - National Science Library

    Murphy, David W; Xue, Xinzhi; Sampath, Kaushik; Katz, Joseph

    2016-01-01

    This study investigates the effects of premixing oil with chemical dispersant at varying concentrations on the flow structure and droplet dynamics within a crude oil jet transitioning into a plume in a crossflow...

  20. Resonant holographic measurements of laser ablation plume expansion in vacuum and argon gas backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Lindley, Roger Alan [Michigan Univ., Ann Arbor, MI (United States)

    1993-01-01

    This thesis discusses the following on resonant holographic measurements of laser ablation plume expansion: Introduction to laser ablation; applications of laser ablation; The study of plume expansion; holographic interferometry; resonant holographic interferometry; accounting for finite laser bandwidth; The solution for doppler broadening and finite bandwidth; the main optical table; the lumonics laser spot shape; developing and reconstructing the holograms; plume expansion in RF/Plasma Environments; Determining λ°; resonant refraction effects; fringe shift interpretation; shot-to-shot consistency; laser ablation in vacuum and low pressure, inert, background gas; theoretically modeling plume expansion in vacuum and low pressure, inert, background gas; and laser ablation in higher pressure, inert, background gas.

  1. Microbial gene functions enriched in the Deepwater Horizon deep-sea oil plume

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Z.; Deng, Y.; Nostrand, J.D. Van; He, Z.; Voordeckers, J.; Zhou, A.; Lee, Y.-J.; Mason, O.U.; Dubinsky, E.; Chavarria, K.; Tom, L.; Fortney, J.; Lamendella, R.; Jansson, J.K.; D?haeseleer, P.; Hazen, T.C.; Zhou, J.

    2011-06-15

    The Deepwater Horizon oil spill in the Gulf of Mexico is the deepest and largest offshore spill in U.S. history and its impacts on marine ecosystems are largely unknown. Here, we showed that the microbial community functional composition and structure were dramatically altered in a deep-sea oil plume resulting from the spill. A variety of metabolic genes involved in both aerobic and anaerobic hydrocarbon degradation were highly enriched in the plume compared to outside the plume, indicating a great potential for intrinsic bioremediation or natural attenuation in the deep-sea. Various other microbial functional genes relevant to carbon, nitrogen, phosphorus, sulfur and iron cycling, metal resistance, and bacteriophage replication were also enriched in the plume. Together, these results suggest that the indigenous marine microbial communities could play a significant role in biodegradation of oil spills in deep-sea environments.

  2. Multiscale GasKinetics/Particle (MGP) Simulation for Rocket Plume/Lunar Dust Interactions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A Multiscale GasKinetic/Particle (MGP) computational method is proposed to simulate the plume-crater-interaction/dust-impingement(PCIDI) problem. The MGP method...

  3. Background gas collisional effects on expanding fs and ns laser ablation plumes

    Science.gov (United States)

    Harilal, S. S.; Farid, N.; Freeman, J. R.; Diwakar, P. K.; LaHaye, N. L.; Hassanein, A.

    2014-10-01

    The collisional effects of a background gas on expanding ultrafast and short pulse laser ablation plumes were investigated by varying background pressure from vacuum to atmospheric pressure levels. For producing Cu ablation plumes, either 40 fs, 800 nm pulses from a Ti: Sapphire laser or 6 ns, 1,064 nm pulses from a Nd:YAG laser were used. The role of background pressure on plume hydrodynamics, spectral emission features, absolute line intensities, signal to background ratios and ablation craters was studied. Though the signal intensities were found to be maximum near to atmospheric pressure levels, the optimum signal to background ratios are observed ~20-50 Torr for both ns and fs laser ablation plumes. The differences in laser-target and laser-plasma couplings between ns and fs lasers were found to be more engraved in the crater morphologies and plasma hydrodynamic expansion features.

  4. Tracking of Fluid-Advected Odor Plumes: Strategies Inspired by Insect Orientation to Pheromone

    National Research Council Canada - National Science Library

    Li, Wei

    2002-01-01

    .... These strategies are inspired by the maneuvers of moths flying upwind along a pheromone plume. Although moth maneuvers are well documented, the mechanisms underlying sensory perception and navigation are not fully understood...

  5. A parametric study of gaseous plume depletion by ground surface adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Markee, E.H. [ARFRO, Environmental Science Services Administration, Idaho Falls, Idaho (United States)

    1967-07-01

    Total plume depletion by ground surface adsorption was calculated via the one dimensional parabolic diffusion equation. Solutions of this differential equation were obtained by digital computer for sets of eddy diffusivity (K) and wind velocity (u) profiles representative of stable, neutral and unstable conditions. Calculations were made for perfect sink and typical partial sink boundary conditions at ground level to a distance of 10{sup 5}m from the source for various source heights. This method of estimating plume depletion was found to be extremely sensitive to K values in the lower levels and source height. The resultant vertical concentration profiles from a depleting plume show markedly non-gaussian distributions with the height of the maximum concentration increasing with travel distance. This departure from the gaussian distribution is most pronounced in stable conditions. It appears that this parabolic diffusion equation provides realistic vertical concentration profiles and, consequently, reasonable plume depletion estimates. (author)

  6. Formation of mantle "lone plumes" in the global downwelling zone - A multiscale modelling of subduction-controlled plume generation beneath the South China Sea

    Science.gov (United States)

    Zhang, Nan; Li, Zheng-Xiang

    2018-01-01

    It has been established that almost all known mantle plumes since the Mesozoic formed above the two lower mantle large low shear velocity provinces (LLSVPs). The Hainan plume is one of the rare exceptions in that instead of rising above the LLSVPs, it is located within the broad global mantle downwelling zone, therefore classified as a "lone plume". Here, we use the Hainan plume example to investigate the feasibility of such lone plumes being generated by subducting slabs in the mantle downwelling zone using 3D geodynamic modelling. Our geodynamic model has a high-resolution regional domain embedded in a relatively low resolution global domain, which is set up in an adaptive-mesh-refined, 3D mantle convection code ASPECT (Advanced Solver for Problems in Earth's ConvecTion). We use a recently published plate motion model to define the top mechanical boundary condition. Our modelling results suggest that cold slabs under the present-day Eurasia, formed from the Mesozoic subduction and closure of the Tethys oceans, have prevented deep mantle hot materials from moving to the South China Sea from regions north or west of the South China Sea. From the east side, the Western Pacific subduction systems started to promote the formation of a lower-mantle thermal-chemical pile in the vicinity of the future South China Sea region since 70 Ma ago. As the top of this lower-mantle thermal-chemical pile rises, it first moved to the west, and finally rested beneath the South China Sea. The presence of a thermochemical layer (possible the D″ layer) in the model helps stabilizing the plume root. Our modelling is the first implementation of multi-scale mesh in the regional model. It has been proved to be an effective way of modelling regional dynamics within a global plate motion and mantle dynamics background.

  7. FINAL TECHNICAL REPORT-THE ECOLOGY AND GENOMICS OF CO2 FIXATIION IN OCEANIC RIVER PLUMES

    Energy Technology Data Exchange (ETDEWEB)

    PAUL, JOHN H

    2013-06-21

    Oceanic river plumes represent some of the most productive environments on Earth. As major conduits for freshwater and nutrients into the coastal ocean, their impact on water column ecosystems extend for up to a thousand km into oligotrophic oceans. Upon entry into the oceans rivers are tremendous sources of CO2 and dissolved inorganic carbon (DIC). Yet owing to increased light transmissivity from sediment deposition coupled with the influx of nutrients, dramatic CO2 drawdown occurs, and plumes rapidly become sinks for CO2. Using state-of-the-art gene expression technology, we have examined the molecular biodiversity of CO2 fixation in the Mississippi River Plume (MRP; two research cruises) and the Orinoco River Plume (ORP; one cruise). When the MRP extends far into the Gulf because of entrainment with the Loop Current, MRP production (carbon fixation) can account for up to 41% of the surface production in the Gulf of Mexico. Nearer-shore plume stations (“high plume,” salinity< 32 ppt) had tremendous CO2 drawdown that was correlated to heterokont (principally diatom) carbon fixation gene expression. The principal form of nitrogen for this production based upon 15N studies was urea, believed to be from anthropogenic origin (fertilizer) from the MRP watershed. Intermediate plume environments (salinity 34 ppt) were characterized by high levels of Synechococcuus carbon fixation that was fueled by regenerated ammonium. Non-plume stations were characterized by high light Prochlorococcus carbon fixation gene expression that was positively correlated with dissolved CO2 concentrations. Although data from the ORP cruise is still being analyzed, some similarities and striking differences were found between the ORP and MRP. High levels of heterokont carbon fixation gene expression that correlated with CO2 drawdown were observed in the high plume, yet the magnitude of this phenomenon was far below that of the MRP, most likely due to the lower levels of anthropogenic

  8. Magnetotelluric Detection Thresholds as a Function of Leakage Plume Depth, TDS and Volume

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Buscheck, T. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mansoor, K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Carroll, S. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-04-21

    We conducted a synthetic magnetotelluric (MT) data analysis to establish a set of specific thresholds of plume depth, TDS concentration and volume for detection of brine and CO2 leakage from legacy wells into shallow aquifers in support of Strategic Monitoring Subtask 4.1 of the US DOE National Risk Assessment Partnership (NRAP Phase II), which is to develop geophysical forward modeling tools. 900 synthetic MT data sets span 9 plume depths, 10 TDS concentrations and 10 plume volumes. The monitoring protocol consisted of 10 MT stations in a 2×5 grid laid out along the flow direction. We model the MT response in the audio frequency range of 1 Hz to 10 kHz with a 50 Ωm baseline resistivity and the maximum depth up to 2000 m. Scatter plots show the MT detection thresholds for a trio of plume depth, TDS concentration and volume. Plumes with a large volume and high TDS located at a shallow depth produce a strong MT signal. We demonstrate that the MT method with surface based sensors can detect a brine and CO2 plume so long as the plume depth, TDS concentration and volume are above the thresholds. However, it is unlikely to detect a plume at a depth larger than 1000 m with the change of TDS concentration smaller than 10%. Simulated aquifer impact data based on the Kimberlina site provides a more realistic view of the leakage plume distribution than rectangular synthetic plumes in this sensitivity study, and it will be used to estimate MT responses over simulated brine and CO2 plumes and to evaluate the leakage detectability. Integration of the simulated aquifer impact data and the MT method into the NRAP DREAM tool may provide an optimized MT survey configuration for MT data collection. This study presents a viable approach for sensitivity study of geophysical monitoring methods for leakage detection. The results come in handy for rapid assessment of leakage detectability.

  9. Evaluation of a Chlorinated Compounds Plume in a Fractured Sandstone Aquifer in Mid- West, US

    Science.gov (United States)

    Miao, Z.; Aravena, R.; Parker, B. L.; Cherry, J. A.; Meyer, J. R.; Hunkeler, D.

    2009-05-01

    A study was carried out in the sedimentary fractured rock site located in Mid West, US, which was impacted by a DNAPL spill estimated to occur in the 1950's and 1960's. The majority of the DNAPL has accumulated in the upper portion of the Lone Rock Formation (referred to as Layer 5) and a VOC plume of more than 3km long has formed. The DNAPL is mainly composed of 1,1,1-TCA, PCE, TCE and BTEX, while large amounts of degradation products such as cis-DCE and 1,1-DCA have been found in the plume. Detailed geochemical and carbon isotope analysis in September 2007 showed that complete degradation of PCE and TCE to cis-DCE in Layer 5 had been achieved from the source to the middle of the plume and the dechlorination reaction stalled at cis-DCE, which is in agreement with the redox condition in this part of the plume. On the other hand, degradation of 1,1,1-TCA to 1,1-DCA was incomplete. The fringes of the plume are characterized by the presence of PCE and TCE in agreement with aerobic conditions in this part of the plume. A historical data review from 1992 to 2006 revealed two phases of degradation in Layer 5. The first phase corresponded with the period before 2001, when there was no significant degradation, while the second phase corresponded with the period after 2001, when significant degradation occurred. The occurrence of the second phase was related to a large scale DNAPL pumping in the source zone during 1999 to 2002, which caused a great increase of contaminant concentrations in the plume including large amounts of ketones and BTEX serving as electron donors and substrates for microbial dechlorination. Thus, subsequent degradation of chlorinated compounds occurred extensively in the plume. The contaminant concentration and the shape of the plume has been modified since 2003 by a hydraulic barrier system. This case study shows that the long term degradation pattern and contaminant distribution at the site has been controlled by plume management practices including

  10. Intracontinental mantle plume and its implications for the Cretaceous tectonic history of East Asia

    Science.gov (United States)

    Ryu, In-Chang; Lee, Changyeol

    2017-12-01

    A-type granitoids, high-Mg basalts (e.g., picrites), adakitic rocks, basin-and-range-type fault basins, thinning of the North China Craton (NCC), and southwest-to-northeast migration of the adakites and I-type granitoids in southern Korea and southwestern Japan during the Cretaceous are attributed to the passive upwelling of deep asthenospheric mantle or ridge subduction. However, the genesis of these features remains controversial. Furthermore, the lack of ridge subduction during the Cretaceous in recently suggested plate reconstruction models poses a problem because the Cretaceous adakites in southern Korea and southwestern Japan could not have been generated by the subduction of the old Izanagi oceanic plate. Here, we speculate that plume-continent (intracontinental plume-China continent) and subsequent plume-slab (intracontinental plume-subducted Izanagi oceanic plate) interactions generated the various intracontinental magmatic and tectonic activities in eastern China, Korea, and southwestern Japan. We support our proposal using three-dimensional numerical models: 1) An intracontinental mantle plume is dragged into the mantle wedge by corner flow of the mantle wedge, and 2) the resultant channel-like flow of the mantle plume in the mantle wedge apparently migrated from southwest to northeast because of the northeast-to-southwest migration of the East Asian continental blocks with respect to the Izanagi oceanic plate. Our model calculations show that adakites and I-type granitoids can be generated by increased slab-surface temperatures because of the channel-like flow of the mantle plume in the mantle wedge. We also show that the southwest-to-northeast migration of the adakites and I-type granitoids in southern Korea and southwestern Japan can be attributable to the opposite migration of the East Asian continental blocks with respect to the Izanagi oceanic plate. This correlation implies that an intracontinental mantle plume existed in eastern China during the

  11. Resolving the Mantle Heat Transfer Discrepancy by Reassessing Buoyancy Flux Estimates of Upwelling Plumes

    Science.gov (United States)

    Hoggard, Mark; Parnell-Turner, Ross; White, Nicky

    2017-04-01

    The size and relative importance of mantle plumes is a controversial topic within the geodynamics community. Numerical experiments of mantle convection suggest a wide range of possible behaviours, from minor plumelets through to large scale, whole-mantle upwellings. In terms of observations, recent seismic tomographic models have identified many large, broad plume-like features within the lower mantle. In contrast, existing estimates of buoyancy flux calculated from plume swells have suggested that these upwellings transfer a relatively minor amount of material and heat into the uppermost mantle. Here, we revisit these calculations of buoyancy flux using a global map of plume swells based upon new observations of dynamic topography. Usually, plume flux is calculated from the cross-sectional area of a swell multiplied by either plate velocity or spreading rate. A key assumption is that plume head material flows laterally at or below the velocity of the overriding plate. Published results are dominated by contributions from the Pacific Ocean and suggest that a total of ˜ 2 TW of heat is carried by plumes into the uppermost mantle. An alternative approach exploits swell volume scaled by a characteristic decay time, which removes the reliance on plate velocities. The main assumption of this method is that plumes are in quasi-steady state. In this study, we have applied this volumetric approach in a new global analysis. Our results indicate that the Icelandic plume has a buoyancy flux of ˜ 27 ± 4 Mg s-1 and the Hawaiian plume is ˜ 2.9 ± 0.6 Mg s-1. These revised values are consistent with independent geophysical constraints from the North Atlantic Ocean and Hawaii. All magmatic and amagmatic swells have been included, suggesting that the total heat flux carried to the base of the plates is ˜ 10 ± 2 TW. This revised value is a five-fold increase compared with previous estimates and provides an improved match to published predictions of basal heat flux across the

  12. Can lower mantle plumes be located using seismic tomography and transition zone topography?

    Science.gov (United States)

    Van Keken, P. E.; Bossmann, A. B.; Ritsema, J. E.; Hwang, Y.; Goes, S. D.

    2012-12-01

    Hotspot volcanism is well explained by fluid dynamical models of plumes rising from great depth in the Earth's mantle. Seismic imaging of these suggested plumes has been difficult and somewhat controversial, as imaged low velocity regions in tomographic models may be due to choices in the inversion techniques. Observations of transition zone topography may be a more robust indication of the presence of hotter-than-normal mantle, but in general the topography of the 670-km phase boundary appears flat, suggesting in part that hotspots have an upper mantle origin. We present new high-resolution finite element models of plumes rising from the core-mantle-boundary using compressible convection with phase changes. Plumes that have a buoyancy flux similar to that of the Hawaiian or Iceland hotspots show a broad high velocity conduit in the lower mantle with significant thinning and time-dependent behavior in the upper mantle. Seismic wave propagation modeling using SHAXI demonstrates that the presence of the low velocity plume causes a distinct later arrival of seismic waves that travel through the upper mantle, but wave front healing renders the strong velocity contrasts in the lower mantle invisible at the Earth's surface. The predicted 400-km phase boundary topography occurs over short wavelengths and is consistent with the observations at a significant number of hotspots. The broad plume anomaly in the uppermost lower mantle causes a slight and very broad uplift of the 670-km topography. This is consistent with the absence of significant topography of 670 as seen by the limited aperture seismic studies. Our modeling suggests that the absence of 670 km topography and difficulties of imaging plumes in tomographic models are inherently due to plume morphology and wave front healing.

  13. The Thermal Plume above a Standing Human Body Exposed to Different Air Distribution Strategies

    DEFF Research Database (Denmark)

    Liu, Li; Nielsen, Peter V.; Li, Yuguo

    2009-01-01

    This study compares the impact of air distribution on the thermal plume above a human body in indoor environment. Three sets of measurements are conducted in a full-scale test room with different ventilation conditions. One breathing thermal manikin standing in the room is used to simulate...... the human body. Long-time average air velocity profiles at locations closely above the manikin are taken to identify the wandering thermal plume....

  14. A multi-sensor plume height analysis of the 2009 Redoubt eruption

    Science.gov (United States)

    Ekstrand, Angela L.; Webley, Peter W.; Garay, Michael J.; Dehn, Jonathan; Prakash, Anupma; Nelson, David L.; Dean, Kenneson G.; Steensen, Torge

    2013-06-01

    During an explosive volcanic eruption, accurately determining the height of a volcanic plume or cloud is essential to accurately forecast its motion because volcanic ash transport and dispersion models require the initial plume height as an input parameter. The direct use of satellite infrared temperatures for height determination, one of the most commonly employed methods at the Alaska Volcano Observatory, often does not yield unique solutions for height. This result is documented here for the 2009 eruption of Redoubt Volcano. Satellite temperature heights consistently underestimated the height of ash plumes in comparison to other methods such as ground-based radar and Multi-angle Imaging SpectroRadiometer (MISR) stereo heights. For ash plumes below the tropopause, increasing transparency of a plume begins to affect the accuracy of simple temperature height retrievals soon after eruption. With decreasing opacity, plume temperature heights become increasingly inaccurate. Comparison with dispersion models and aircraft gas flight data confirms that radar and MISR stereo heights are more accurate than basic satellite temperature heights. Even in the cases in which satellite temperature results appeared to be relatively accurate (e.g., for plumes below the tropopause), a mixed signal of plume and ground radiation still presented an issue for almost every event studied. This was true regardless of the fact that a band differencing method was used to remove presumably translucent pixels. The data presented here make a strong case for the use of data fusion in volcano monitoring, as there is a need to confirm satellite temperature heights with other height data. If only basic satellite temperature heights are available for a given eruption, then these heights must be considered with a significant margin of error.

  15. Seasonal occurrence of unique sediment plume in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Sridhar, P.N.; Ali, M.M.; Vethamony, P.; Babu, M.T.; Ramana, I.V.; Jayakumar, S.

    , and intensity of this plume have both seasonal and interannual variations. In order to delineate this plume and the current pattern that controls its behavior, we superimposed the geostrophic currents (which are generated through a balance between... Drilling Program, MARGINS and InterMargins, RIDGE2000 and InterRIDGE, and now the NSF’s Ocean Observing Initia- tive. Specific discussions included (1) com- bining conductive marine heat flow data with new technologies for measuring the advective...

  16. Expansion of the laser ablation vapor plume into a background gas: Part A, Analysis

    OpenAIRE

    Wen, Sy-Bor; Mao, Xianglei; Greif, Ralph; Russo, Richard E.

    2006-01-01

    A study of the gas dynamics of the vapor plume generated during laser ablation was conducted including a counterpropagating internal shock wave. The density, pressure, and temperature distributions between the external shock wave front and the sample surface were determined by solving the integrated conservation equations of mass, momentum, and energy. The positions of the shock waves and the contact surface (boundary that separates the compressed ambient gas and the vapor plume) were ob...

  17. The review of the IR radiation characteristic of exhaust plume of the liquid rocket engine

    Science.gov (United States)

    Wu, Hanyang; Sheng, Weidong; An, Wei; Zeng, Jian; Yang, Yuanyuan

    2017-02-01

    At present, there are various methods to compute the infrared radiation characteristics of exhaust plume of the liquid rocket engine. Though they are different in computational complexity. Their ideas and methods are alike. This paper focuses on the computation methods of exhaust plume's flow field, spectral parameters and radiation transfer equation. Comparison, analysis and conclusion of these methods are presented. Furthermore, existing problems and improvements of them are proposed as well.

  18. Micro-physics of aircraft-generated aerosols and their potential impact on heterogeneous plume chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Kaercher, B.; Luo, B.P. [Muenchen Univ., Freising (Germany). Lehrstuhl fuer Bioklimatologie und Immissionsforschung

    1997-12-31

    Answers are attempted to give to open questions concerning physico-chemical processes in near-field aircraft plumes, with emphasis on their potential impact on subsequent heterogeneous chemistry. Research issues concerning the nucleation of aerosols and their interactions among themselves and with exhaust gases are summarized. Microphysical properties of contrail ice particles, formation of liquid ternary mixtures, and nucleation of nitric acid trihydrate particles in contrails are examined and possible implications for heterogeneous plume chemistry are discussed. (author) 19 refs.

  19. Development of an open-path gas analyser for plume detection in security applications

    Science.gov (United States)

    Hay, Kenneth G.; Norberg, Ola; Normand, Erwan; Önnerud, Hans; Black, Paul

    2017-04-01

    We present here an open-path analyser, initially intended for security applications, specifically for the detection of gas plumes from illicit improvised explosive device (IED) manufacturing. Subsequently, the analysers were adapted for methane measurement and used to investigate its applicability for leak detection in different scenarios (e.g. unconventional gas extraction sites). Preliminary results showed consistent measurements of gas plumes in the open path.

  20. Observations of The Dense Storfjord Plume Using A Ctd-mounted Adp

    Science.gov (United States)

    Fer, I.; Skogseth, R.; Haugan, P. M.

    Observations were made of the outflow of the dense bottom water plume from Stor- fjord (110 km long and 190 m deep at maximum depth) in the Svalbard Archipelago, using a CTD mounted ADP at densely spaced hydrographic stations during May 28 - June 2, 2001. Due to heavy ice inside the fjord, measurements were made from about 70 km downstream of a 115 m deep sill (7645 N) and onward. The dense bottom water generated by strong winter cooling, enhanced ice formation, and the consequent brine rejection drains into and fills the depressions of the fjord and cascades following the bathymetry. Data acquired by ADP allow for examination of the velocity structure associated with the plume as close as 1 m to the bottom with 1 m resolution in the vertical. The plume water was observed to have salinities within 34.9 - 35.1 psu with temperatures close to the freezing point temperature. The plume has a thickness of 51 +/- 20 m, and a density difference of 0.14 +/- 0.03 kg m-3 from the ambient wa- ters. The velocity profiles yield the most well-defined two-layered structure near the sloping sides with a mean plume speed of 0.15 +/- 0.04 m s-1, relative to the ambient waters. Mean overall Richardson number, estimated using these profiles, are within the range of 2 to 4. The plume is less distinct with respect to the velocity profile when it reaches the plane, Storfjordrenna, after cascading about 50 m in vertical. The width of the plume increases from about 8 km to 25 km along its path of 105 km leading to an entrainment rate of 5x10-4, when the plume thickness and speed are assumed constant. The values compare well with those obtained from moorings in the same region in the past, as well as those obtained from laboratory experiments of turbulent gravity currents flowing down a slope.

  1. The geomicrobiology of iron in deep-sea hydrothermal plumes (Invited)

    Science.gov (United States)

    Dick, G.; Li, M.; Toner, B. M.; Cron-Kamermans, B.; Baker, B. J.; Breier, J. A.; Sheik, C. S.

    2013-12-01

    Deep-sea hydrothermal vents are a significant source of iron and manganese to the oceans. Microorganisms in deep-sea hydrothermal plumes can influence the form and oceanic fate of vent-derived iron and manganese in several ways, including catalyzing the formation of iron and manganese oxides as well as binding and stabilizing iron with microbially-produced organic carbon. Although the potential role of organic ligands in dispersal of iron from vents is now well established, the nature and source of this organic matter is unknown. Here we present metagenomic, metatranscriptomic, and geochemical insights into the geomicrobiology of iron in deep-sea hydrothermal plumes of the Guaymas Basin (Gulf of California) and Mid-Cayman Rise (Caribbean). In the Guaymas Basin, genes involved in cellular iron uptake pathways, especially those involving siderophores, are among the most highly expressed genes in the plume microbial community. The nature of these microbial iron transporters, taken together with the low concentration of dissolved iron and abundance of particulate iron (mainly maghemite, lepidocrocite, and hematite) in the plume, indicates that iron minerals are the target for this microbial scavenging and uptake. All major Guaymas plume populations, including widespread methanotrophs, lithotrophs, and a particle-associated heterotroph, participate in iron uptake. At the Mid-Cayman Rise, an abundant plume population of Methylophaga has a cluster of genes involved in siderophore production and uptake that are expressed in the plume. These genes are not present in the genomes of other closely-related Methylophaga. Our findings indicate that the mobilization and cellular uptake of iron is a major process in deep-sea hydrothermal plume microbial communities and suggest new mechanisms for generating Fe-C complexes. This 'microbial iron pump' could represent an important yet previously overlooked mode of converting hydrothermal iron into bioavailable forms that can be

  2. Plume-exit modeling to determine cloud condensation nuclei activity of aerosols from residential biofuel combustion

    Science.gov (United States)

    Mena, Francisco; Bond, Tami C.; Riemer, Nicole

    2017-08-01

    Residential biofuel combustion is an important source of aerosols and gases in the atmosphere. The change in cloud characteristics due to biofuel burning aerosols is uncertain, in part, due to the uncertainty in the added number of cloud condensation nuclei (CCN) from biofuel burning. We provide estimates of the CCN activity of biofuel burning aerosols by explicitly modeling plume dynamics (coagulation, condensation, chemical reactions, and dilution) in a young biofuel burning plume from emission until plume exit, defined here as the condition when the plume reaches ambient temperature and specific humidity through entrainment. We found that aerosol-scale dynamics affect CCN activity only during the first few seconds of evolution, after which the CCN efficiency reaches a constant value. Homogenizing factors in a plume are co-emission of semi-volatile organic compounds (SVOCs) or emission at small particle sizes; SVOC co-emission can be the main factor determining plume-exit CCN for hydrophobic or small particles. Coagulation limits emission of CCN to about 1016 per kilogram of fuel. Depending on emission factor, particle size, and composition, some of these particles may not activate at low supersaturation (ssat). Hygroscopic Aitken-mode particles can contribute to CCN through self-coagulation but have a small effect on the CCN activity of accumulation-mode particles, regardless of composition differences. Simple models (monodisperse coagulation and average hygroscopicity) can be used to estimate plume-exit CCN within about 20 % if particles are unimodal and have homogeneous composition, or when particles are emitted in the Aitken mode even if they are not homogeneous. On the other hand, if externally mixed particles are emitted in the accumulation mode without SVOCs, an average hygroscopicity overestimates emitted CCN by up to a factor of 2. This work has identified conditions under which particle populations become more homogeneous during plume processes. This

  3. Two Plumes Beneath the East African Rift System: a Geochemical Investigation into Possible Interactions in Ethiopia

    Science.gov (United States)

    Nelson, W. R.; Furman, T.; van Keken, P. E.; Lin, S.

    2007-12-01

    East African Rift System magmatism began over 40 my ago and has continued through the present. Numerical models have determined two plumes are necessary to create the spatial and temporal distribution of volcanism. Geochemical data support the presence of two chemically distinct plumes initially located beneath the Afar Depression (NE Ethiopia) and the Turkana Depression (SW Ethiopia/N Kenya). The timing and eruptive of the Afar and Kenya plumes are also distinct. While there is growing evidence to support the existence of two dynamically and chemically distinct plumes beneath the East African Rift System, the interactions between them remain unclear. Our study focuses on the geochemistry of mafic shield lavas from three locations on the eastern flank of the Ethiopian plateau. These lavas are spatially located between the surface manifestation of the Afar and Kenya plumes. The majority of the lava is alkaline and has experienced varying degrees of olivine and pyroxene fractionation. The northernmost lavas (9°10'N) are transitional and display the most fractionation. Primitive mantle melts were generated at depths near the fertile mantle garnet-spinel transition zone and deeper (80-100km) and are free of metasomatic influence. Minor HREE depletions also support derivation of melts from a garnet-bearing source. Lavas with lithospheric influence are generated from shallower depths and show minor amphibole influence. Overall, geochemical data show the lavas in this study closely resemble those from various episodes of Kenya plume magmatism with modifications attributed to lithospheric contamination. This interpretation is consistent with current numerical models suggesting episodic northward movement of Kenya plume magmas along the lithosphere-asthenosphere boundary. The data imply that the Kenya plume has a much larger spatial influence and therefore a larger geodynamic influence in the EARS than previously recognized.

  4. Plume-exit modeling to determine cloud condensation nuclei activity of aerosols from residential biofuel combustion

    Directory of Open Access Journals (Sweden)

    F. Mena

    2017-08-01

    Full Text Available Residential biofuel combustion is an important source of aerosols and gases in the atmosphere. The change in cloud characteristics due to biofuel burning aerosols is uncertain, in part, due to the uncertainty in the added number of cloud condensation nuclei (CCN from biofuel burning. We provide estimates of the CCN activity of biofuel burning aerosols by explicitly modeling plume dynamics (coagulation, condensation, chemical reactions, and dilution in a young biofuel burning plume from emission until plume exit, defined here as the condition when the plume reaches ambient temperature and specific humidity through entrainment. We found that aerosol-scale dynamics affect CCN activity only during the first few seconds of evolution, after which the CCN efficiency reaches a constant value. Homogenizing factors in a plume are co-emission of semi-volatile organic compounds (SVOCs or emission at small particle sizes; SVOC co-emission can be the main factor determining plume-exit CCN for hydrophobic or small particles. Coagulation limits emission of CCN to about 1016 per kilogram of fuel. Depending on emission factor, particle size, and composition, some of these particles may not activate at low supersaturation (ssat. Hygroscopic Aitken-mode particles can contribute to CCN through self-coagulation but have a small effect on the CCN activity of accumulation-mode particles, regardless of composition differences. Simple models (monodisperse coagulation and average hygroscopicity can be used to estimate plume-exit CCN within about 20 % if particles are unimodal and have homogeneous composition, or when particles are emitted in the Aitken mode even if they are not homogeneous. On the other hand, if externally mixed particles are emitted in the accumulation mode without SVOCs, an average hygroscopicity overestimates emitted CCN by up to a factor of 2. This work has identified conditions under which particle populations become more homogeneous during plume

  5. Plume and lithologic profiling with surface resistivity and seismic tomography

    Energy Technology Data Exchange (ETDEWEB)

    Watson, David B [ORNL; Doll, William E. [Battelle; Gamey, Jeff [Battelle; Sheehan, Jacob R [ORNL; Jardine, Philip M [ORNL

    2005-03-01

    Improved surface-based geophysical technologies that are commercially available provide a new level of detail that can be used to guide ground water remediation. Surface-based multielectrode resistivity methods and tomographic seismic refraction techniques were used to image to a depth of approximately 30 m below the surface at the Natural and Accelerated Bioremediation Research Field Research Center. The U.S. Department of Energy (DOE) established the research center on the DOE Oak Ridge Reservation in Oak Ridge, Tennessee, to conduct in situ field-scale studies on bioremediation of metals and radionuclides. Bioremediation studies are being conducted on the saprolite, shale bedrock, and ground water at the site that have been contaminated with nitrate, uranium, technetium, tetrachloroethylene, and other contaminants (U.S. DOE 1997). Geophysical methods were effective in imaging the high-ionic strength plume and in defining the transition zone between saprolite and bedrock zones that appears to have a significant influence on contaminant transport. The geophysical data were used to help select the location and depth of investigation for field research plots. Drilling, borehole geophysics, and ground water sampling were used to verify the surface geophysical studies.

  6. Hail formation triggers rapid ash aggregation in volcanic plumes.

    Science.gov (United States)

    Van Eaton, Alexa R; Mastin, Larry G; Herzog, Michael; Schwaiger, Hans F; Schneider, David J; Wallace, Kristi L; Clarke, Amanda B

    2015-08-03

    During explosive eruptions, airborne particles collide and stick together, accelerating the fallout of volcanic ash and climate-forcing aerosols. This aggregation process remains a major source of uncertainty both in ash dispersal forecasting and interpretation of eruptions from the geological record. Here we illuminate the mechanisms and timescales of particle aggregation from a well-characterized 'wet' eruption. The 2009 eruption of Redoubt Volcano, Alaska, incorporated water from the surface (in this case, a glacier), which is a common occurrence during explosive volcanism worldwide. Observations from C-band weather radar, fall deposits and numerical modelling demonstrate that hail-forming processes in the eruption plume triggered aggregation of ∼95% of the fine ash and stripped much of the erupted mass out of the atmosphere within 30 min. Based on these findings, we propose a mechanism of hail-like ash aggregation that contributes to the anomalously rapid fallout of fine ash and occurrence of concentrically layered aggregates in volcanic deposits.

  7. Modeling surf zone tracer plumes: 2. Transport and dispersion

    Science.gov (United States)

    Clark, David B.; Feddersen, Falk; Guza, R. T.

    2011-11-01

    Five surf zone dye tracer releases from the HB06 experiment are simulated with a tracer advection diffusion model coupled to a Boussinesq surf zone model (funwaveC). Model tracer is transported and stirred by currents and eddies and diffused with a breaking wave eddy diffusivity, set equal to the breaking wave eddy viscosity, and a small (0.01 m2 s-1) background diffusivity. Observed and modeled alongshore parallel tracer plumes, transported by the wave driven alongshore current, have qualitatively similar cross-shore structures. Although the model skill for mean tracer concentration is variable (from negative to 0.73) depending upon release, cross-shore integrated tracer moments (normalized by the cross-shore tracer integral) have consistently high skills (≈0.9). Modeled and observed bulk surf zone cross-shore diffusivity estimates are also similar, with 0.72 squared correlation and skill of 0.4. Similar to the observations, the model bulk (absolute) cross-shore diffusivity is consistent with a mixing length parameterization based on low-frequency (0.001-0.03 Hz) eddies. The model absolute cross-shore dispersion is dominated by stirring from surf zone eddies and does not depend upon the presence of the breaking wave eddy diffusivity. Given only the bathymetry and incident wave field, the coupled Boussinesq-tracer model qualitatively reproduces the observed cross-shore absolute tracer dispersion, suggesting that the model can be used to study surf zone tracer dispersion mechanisms.

  8. Plume-subduction interaction forms large auriferous provinces.

    Science.gov (United States)

    Tassara, Santiago; González-Jiménez, José M; Reich, Martin; Schilling, Manuel E; Morata, Diego; Begg, Graham; Saunders, Edward; Griffin, William L; O'Reilly, Suzanne Y; Grégoire, Michel; Barra, Fernando; Corgne, Alexandre

    2017-10-10

    Gold enrichment at the crustal or mantle source has been proposed as a key ingredient in the production of giant gold deposits and districts. However, the lithospheric-scale processes controlling gold endowment in a given metallogenic province remain unclear. Here we provide the first direct evidence of native gold in the mantle beneath the Deseado Massif in Patagonia that links an enriched mantle source to the occurrence of a large auriferous province in the overlying crust. A precursor stage of mantle refertilisation by plume-derived melts generated a gold-rich mantle source during the Early Jurassic. The interplay of this enriched mantle domain and subduction-related fluids released during the Middle-Late Jurassic resulted in optimal conditions to produce the ore-forming magmas that generated the gold deposits. Our study highlights that refertilisation of the subcontinental lithospheric mantle is a key factor in forming large metallogenic provinces in the Earth's crust, thus providing an alternative view to current crust-related enrichment models.The lithospheric controls on giant gold deposits remain unclear. Here, the authors show evidence for native gold in the mantle from the Deseado Massif in Patagonia demonstrating that refertilisation of the lithospheric mantle is key in forming metallogenic provinces.

  9. [Terminal electron acceptor process in landfill leachate pollution plume].

    Science.gov (United States)

    Dong, Jun; Zhao, Yong-Sheng; Zhang, Wei-Hong; Hong, Mei; Liu, Ying-Ying; Han, Rong

    2008-03-01

    A soil column filled with sandy soil was constructed to investigate changes of terminal electron acceptors (TEA) and TOC in redox zones of landfill leachate pollution plume, and their models were established, respectively. Results indicated that the time of peak-concentration appearance of different reducing products was related to the ability of terminal electron acceptors to compete for terminal electrons. The most competitive ones showed sharp concentration increased earlier. For example, the peak concentration of NO2(-) appeared earlier than that of Fe2+. The concentration of TOC increased in methanogenic zone, iron reduction zone, nitrate reduction zone and oxygen reduction zone, and its rate was 8.27, 8.56, 8.85, 9.06 and 9.11 mg/(L h), respectively. Degradation rate of contaminants by different microbes mainly depended on the amount and availability of terminal electron acceptors. The reaction rate was related to ability of terminal electron acceptors to compete for terminal electron, that is the stronger the ability of terminal electron acceptors to compete for terminal electrons, the easier could be used and consumed by microorganisms and the more sensitive to reflect on environmental pollution.

  10. Enceladus plume density from Cassini spacecraft attitude control data

    Science.gov (United States)

    Lorenz, Ralph D.; Burk, Thomas A.

    2018-01-01

    The plumes of Enceladus are of interest both as a geophysical phenomenon, and as an astrobiological opportunity for sampling internal material. Here we report measurements of the total mass density (gas plus dust, a combination not reported before except in the engineering literature) deduced from telemetry of Cassini's Attitude and Articulation Control System (AACS), as the spacecraft's thrusters or reaction wheels worked to maintain the desired attitude in the presence of drag torques during close flybys. The drag torque shows good agreement with the water vapor density measured by other instruments during the E5 encounter, but indicates a rather higher mass density on other passes (E3, E14), possibly indicating variations in gas composition and/or gas:dust ratio. The spacecraft appears to have intercepted about 0.2 g of material, on flyby E21 in October 2015 indicating a peak mass density of ∼5.5 × 10-11 kg m-3, the highest of all the flybys measured (E3, E5, E7, E9, E14, E21).

  11. A Balloon Sounding Technique for Measuring SO2 Plumes

    Science.gov (United States)

    Morris, Gary A.; Komhyr, Walter D.; Hirokawa, Jun; Lefer, Barry; Krotkov, Nicholay; Ngan, Fong

    2010-01-01

    This paper reports on the development of a new technique for inexpensive measurements of SO2 profiles using a modified dual-ozonesonde instrument payload. The presence of SO2 interferes with the standard electrochemical cell (ECC) ozonesonde measurement, resulting in -1 molecule of O3 reported for each molecule of SO2 present (provided [O3] > [SO2]). In laboratory tests, an SO2 filter made with Cr03 placed on the inlet side of the sonde removes nearly 100% of the SO2 present for concentrations up to 60 ppbv and remained effective after exposure to 2.8 X 10(exp 16) molecules of SO2 [equivalent to a column approximately 150 DU (1 DU = 2.69 X 10(exp 20) molecules m(exp -2))]. Flying two ECC instruments on the same payload with one filtered and the other unfiltered yields SO2 profiles, inferred by subtraction. Laboratory tests and field experience suggest an SO2 detection limit of approximately 3 pbb with profiles valid from the surface to the ozonopause [i.e., approximately (8-10 km)]. Two example profiles demonstrate the success of this technique for both volcanic and industrial plumes.

  12. Imaging trace gases in volcanic plumes with Fabry Perot Interferometers

    Science.gov (United States)

    Kuhn, Jonas; Platt, Ulrich; Bobrowski, Nicole; Lübcke, Peter; Wagner, Thomas

    2017-04-01

    Within the last decades, progress in remote sensing of atmospheric trace gases revealed many important insights into physical and chemical processes in volcanic plumes. In particular, their evolution could be studied in more detail than by traditional in-situ techniques. A major limitation of standard techniques for volcanic trace gas remote sensing (e.g. Differential Optical Absorption Spectroscopy, DOAS) is the constraint of the measurement to a single viewing direction since they use dispersive spectroscopy with a high spectral resolution. Imaging DOAS-type approaches can overcome this limitation, but become very time consuming (of the order of minutes to record a single image) and often cannot match the timescales of the processes of interest for volcanic gas measurements (occurring at the order of seconds). Spatially resolved imaging observations with high time resolution for volcanic sulfur dioxide (SO2) emissions became possible with the introduction of the SO2-Camera. Reducing the spectral resolution to two spectral channels (using interference filters) that are matched to the SO2 absorption spectrum, the SO2-Camera is able to record full frame SO2 slant column density distributions at a temporal resolution on the order of proof of concept studies and proposals for technical implementations are presented.

  13. Jet engine noise and infrared plume correlation field campaign

    Science.gov (United States)

    Cunio, Phillip M.; Weber, Reed A.; Knobel, Kimberly R.; Smith, Christine; Draudt, Andy

    2015-09-01

    Jet engine noise can be a health hazard and environmental pollutant, particularly affecting personnel working in close proximity to jet engines, such as airline mechanics. Mitigating noise could reduce the potential for hearing loss in runway workers; however, there exists a very complex relationship between jet engine design parameters, operating conditions, and resultant noise power levels, and understanding and characterizing this relationship is a key step in mitigating jet engine noise effects. We demonstrate initial results highlighting the utility of high-speed imaging (hypertemporal imaging) in correlating the infrared signatures of jet engines with acoustic noise. This paper builds on prior theoretical analysis of jet engine infrared signatures and their potential relationships to jet engine acoustic emissions. This previous work identified the region of the jet plume most likely to emit both in infrared and in acoustic domains, and it prompted the investigation of wave packets as a physical construct tying together acoustic and infrared energy emissions. As a means of verifying these assertions, a field campaign to collect relevant data was proposed, and data collection was carried out with a bank of infrared instruments imaging a T700 turboshaft engine undergoing routine operational testing. The detection of hypertemporal signatures in association with acoustic signatures of jet engines enables the use of a new domain in characterizing jet engine noise. This may in turn enable new methods of predicting or mitigating jet engine noise, which could lead to socioeconomic benefits for airlines and other operators of large numbers of jet engines.

  14. Tropical biomass burning smoke plume size, shape, reflectance, and age based on 2001–2009 MISR imagery of Borneo

    Directory of Open Access Journals (Sweden)

    C. S. Zender

    2012-04-01

    Full Text Available Land clearing for crops, plantations and grazing results in anthropogenic burning of tropical forests and peatlands in Indonesia, where images of fire-generated aerosol plumes have been captured by the Multi-angle Imaging SpectroRadiometer (MISR since 2001. Here we analyze the size, shape, optical properties, and age of distinct fire-generated plumes in Borneo from 2001–2009. The local MISR overpass at 10:30 a.m. misses the afternoon peak of Borneo fire emissions, and may preferentially sample longer plumes from persistent fires burning overnight. Typically the smoke flows with the prevailing southeasterly surface winds at 3–4 m s−1, and forms ovoid plumes whose mean length, height, and cross-plume width are 41 km, 708 m, and 27% of the plume length, respectively. 50% of these plumes have length between 24 and 50 km, height between 523 and 993 m and width between 18% and 30% of plume length. Length and cross-plume width are lognormally distributed, while height follows a normal distribution. Borneo smoke plume heights are similar to previously reported plume heights, yet Borneo plumes are on average nearly three times longer than previously studied plumes. This could be due to sampling or to more persistent fires and greater fuel loads in peatlands than in other tropical forests. Plume area (median 169 km2, with 25th and 75th percentiles at 99 km2 and 304 km2, respectively varies exponentially with length, though for most plumes a linear relation provides a good approximation. The MISR-estimated plume optical properties involve greater uncertainties than the geometric properties, and show patterns consistent with smoke aging. Optical depth increases by 15–25% in the down-plume direction, consistent with hygroscopic growth and nucleation overwhelming the effects of particle dispersion. Both particle single-scattering albedo and top-of-atmosphere reflectance peak about halfway down-plume, at

  15. Statistical and geometrical properties of thermal plumes in turbulent Rayleigh-B\\'{e}nard convection

    CERN Document Server

    Zhou, Quan

    2010-01-01

    We present a systematic experimental study of geometric and statistical properties of thermal plumes in turbulent Rayleigh-B\\'{e}nard convection using the thermochromic-liquid-crystal (TLC) technique. The experiments were performed in three water-filled cylindrical convection cells with aspect ratios 2, 1, and 0.5 and over the Rayleigh-number range $5\\times10^7 \\leq Ra \\leq 10^{11}$. TLC thermal images of horizontal plane cuts at various depths below the top plate were acquired. Three-dimensional images of thermal plumes were then reconstructed from the two-dimensional slices of the temperature field. The results show that the often-called sheetlike plumes are really one-dimensional structures and may be called rodlike plumes. We find that the number densities for both sheetlike/rodlike and mushroomlike plumes have power-law dependence on $Ra$ with scaling exponents of $\\sim 0.3$, which is close to that between the Nusselt number $Nu$ and $Ra$. This result suggests that it is the plume number that primarily d...

  16. Cart3D Analysis of Plume and Shock Interaction Effects on Sonic Boom

    Science.gov (United States)

    Castner, Raymond

    2015-01-01

    A plume and shock interaction study was developed to collect data and perform CFD on a configuration where a nozzle plume passed through the shock generated from the wing or tail of a supersonic vehicle. The wing or tail was simulated with a wedge-shaped shock generator. Three configurations were analyzed consisting of two strut mounted wedges and one propulsion pod with an aft deck from a low boom vehicle concept. Research efforts at NASA were intended to enable future supersonic flight over land in the United States. Two of these efforts provided data for regulatory change and enabled design of low boom aircraft. Research has determined that sonic boom is a function of aircraft lift and volume distribution. Through careful tailoring of these variables, the sonic boom of concept vehicles has been reduced. One aspect of vehicle tailoring involved how the aircraft engine exhaust interacted with aft surfaces on a supersonic aircraft, such as the tail and wing trailing edges. In this work, results from Euler CFD simulations are compared to experimental data collected on sub-scale components in a wind tunnel. Three configurations are studied to simulate the nozzle plume interaction with representative wing and tail surfaces. Results demonstrate how the plume and tail shock structure moves with increasing nozzle pressure ratio. The CFD captures the main features of the plume and shock interaction. Differences are observed in the plume and deck shock structure that warrant further research and investigation.

  17. Three-Dimensional Numerical Analysis of LOX/Kerosene Engine Exhaust Plume Flow Field Characteristics

    Directory of Open Access Journals (Sweden)

    Hong-hua Cai

    2017-01-01

    Full Text Available Aiming at calculating and studying the flow field characteristics of engine exhaust plume and comparative analyzing the effects of different chemical reaction mechanisms on the engine exhaust plume flow field characteristics, a method considering fully the combustion state influence is put forward, which is applied to exhaust plume flow field calculation of multinozzle engine. On this basis, a three-dimensional numerical analysis of the effects of different chemical reaction mechanisms on LOX/kerosene engine exhaust plume flow field characteristics was carried out. It is found that multistep chemical reaction can accurately describe the combustion process in the LOX/kerosene engine, the average chamber pressure from the calculation is 4.63% greater than that of the test, and the average chamber temperature from the calculation is 3.34% greater than that from the thermodynamic calculation. The exhaust plumes of single nozzle and double nozzle calculated using the global chemical reaction are longer than those using the multistep chemical reaction; the highest temperature and the highest velocity on the plume axis calculated using the former are greater than that using the latter. The important influence of chemical reaction mechanism must be considered in the study of the fixing structure of double nozzle engine on the rocket body.

  18. Exploring a Plume-Based Mass-Flux Scheme in the Boundary-Layer Gray Zone

    Science.gov (United States)

    Weismüller, M.; Heus, T.; Neggers, R.

    2015-12-01

    We investigate the behavior of plume-based mass flux parameterizations in the gray zone of boundary layer convection, to inform the development of scale-aware and scale-adaptive parameterizations. To this end, the Eddy Diffusivity Mass Flux scheme with multiple plumes, named ED(MF)n, is implemented in a Large-Eddy Simulation (LES) model. This way, the LES is used as a non-hydrostatic larger-scale model, providing a convenient platform for investigating the behavior of parameterizations across the boundary-layer gray zone. First, as a feasibility study, a single plume is launched in every column of the LES in an offline, diagnostic way, without affecting the simulation. We find that the plumes are sensitive to the LES columns in which they rise, feeling the presence of LES clouds. A plume budget analysis shows that the plume termination height is mostly determined by the mixing term, and not so much by the buoyancy term. Then, the ED(MF)n is made interactive with the resolved flow, replacing the LES-subgrid scheme. The work performed by the scheme reduces with increasing LES resolution, due to the size-filtering applied in the ED(MF)n framework. An encouraging result is that the total specific humidity flux is conserved across the investigated range of LES resolutions, covering the gray zone between 10m (large-eddy resolving) and 10km (regional-scale). The sensitivity of the results to various model parameters is assessed.

  19. Tectonic plates, D (double prime) thermal structure, and the nature of mantle plumes

    Science.gov (United States)

    Lenardic, A.; Kaula, W. M.

    1994-01-01

    It is proposed that subducting tectonic plates can affect the nature of thermal mantle plumes by determining the temperature drop across a plume source layer. The temperature drop affects source layer stability and the morphology of plumes emitted from it. Numerical models are presented to demonstrate how introduction of platelike behavior in a convecting temperature dependent medium, driven by a combination of internal and basal heating, can increase the temperature drop across the lower boundary layer. The temperature drop increases dramatically following introduction of platelike behavior due to formation of a cold temperature inversion above the lower boundary layer. This thermal inversion, induced by deposition of upper boundary layer material to the system base, decays in time, but the temperature drop across the lower boundary layer always remains considerably higher than in models lacking platelike behavior. On the basis of model-inferred boundary layer temperature drops and previous studies of plume dynamics, we argue that generally accepted notions as to the nature of mantle plumes on Earth may hinge on the presence of plates. The implication for Mars and Venus, planets apparently lacking plate tectonics, is that mantle plumes of these planets may differ morphologically from those of Earth. A corollary model-based argument is that as a result of slab-induced thermal inversions above the core mantle boundary the lower most mantle may be subadiabatic, on average (in space and time), if major plate reorganization timescales are less than those acquired to diffuse newly deposited slab material.

  20. Characterization of Ultrafast Laser-Ablation Plasma Plumes at Various Ar Ambient Pressures

    Energy Technology Data Exchange (ETDEWEB)

    Diwakar, P. K.; Harilal, S. S.; Phillips, Mark C.; Hassanein, A.

    2015-07-28

    Expansion dynamics and internal plume structures of fs laser ablated brass plasma in Ar at various pressure levels ranging from vacuum to atmospheric were studied using multitude of diagnostic tools including time resolved and time integrated 2-dimensional imaging, optical time of flight measurements and visible emission spectroscopy. Temporal evolution of excited Cu and Zn species in the plume were imaged using band pass interference filters and compared its hydrodynamic expansion features with spectrally integrated images of the plume. 2D imaging coupled with monochromatic line selection showed several interesting features at various pressure levels which include velocity differences among the plume species, emission intensity distribution, plasma temperature, electron density etc. Plume confinement, enhanced signal intensity, and dual peak structures in time-of-flight profiles were observed at intermediate pressure range of ~10 Torr. Optimum signal to background ratio was also observed in this pressure range. Possible mechanisms for observed changes in plume shape, optical emission intensity and dual peak structures in time-of-flight profiles were discussed.

  1. Chemical and Trajectory Analysis of an Air Mass Plume from Asia

    Science.gov (United States)

    Guo, J. J.; Marrero, J. E.; Blake, D. R.

    2014-12-01

    Tracking the source of pollution events is important in understanding the transport of pollution plumes and impact on areas far from the source. Previous studies have shown that the rising contribution of Asian air pollution to the US has increased the number of days that pollution events exceed National Ambient Air Quality Standards (NAAQS). Whole air samples collected over the Edwards Air Force Base during a June 2014 NASA Student Airborne Research Program (SARP) flight exhibited enhancements in the concentrations of several compounds between 23-32 thousand feet. Chemical tracer analysis of these high altitude samples reveal that the air does not correspond to California emitted air. Chemical signatures in the plume, including high levels of OCS, chloroform, and methyl chloride, and low levels of methyl bromide, indicate that the plume was most heavily influence by coal combustion with contributions from biomass burning events from Asia. Low concentrations of ethene at the high altitude despite enhanced concentrations of ethane and ethyne suggest that this plume was aged. Further analysis of the plume using meteorological wind trajectories reveal that the plume had originated in China approximately 4-5 days prior. This is faster than results from previous studies that had found a Spring transport time of approximately 6 days.

  2. Injection Heights from MISR of Grassland Fire Smoke Plumes in Australia, and Possible Role of Pyroconvection

    Science.gov (United States)

    Mims, S. R.; Kahn, R. A.; Moroney, C. M.; Gaitley, B. J.

    2009-12-01

    Atmospheric models use smoke plume injection heights from wildfires to forecast transport of aerosols and their consequent impact on atmospheric chemistry and climate. We used stereo-height algorithms from the Multi-angle Imaging SpectroRadiometer (MISR) to examine injection heights of grassland fires in the desert regions of western and central Australia. We found that, in about 10 to 30% of the cases studied, the plumes rose above the planetary boundary layer (PBL). These results were unexpected as many climate models assume that smoke from grassfires stays within the PBL. Smoke that gets above the PBL can travel farther and have a greater impact on human health and the climate. Subsequently, we observed smoke plumes in about 60 of nearly 400 MISR orbits above grassland regions in Australia searched during the austral summers in select years between 2000 and 2009. Pyrocumulus clouds were associated with plumes in about 15% of the MISR orbits where grassland fire smoke plumes were observed. In our analyses, we quantified the heights and size of the pyrocumuli and compared them to the heights of the adjacent smoke plumes. In a few instances, smoke alone appeared to rise above the PBL and sometimes as high as nearby pyrocumulus. Pyroconvection could play a role in pushing the smoke from grassfires above the PBL within the free troposphere, and could be an important consideration for climate modelers.

  3. Effects of Cr2O3 Activating Flux on the Plasma Plume in Pulsed Laser Welding

    Science.gov (United States)

    Yi, Luo; Yunfei, Du; Xiaojian, Xie; Rui, Wan; Liang, Zhu; Jingtao, Han

    2016-11-01

    The effects of Cr2O3 activating flux on pulsed YAG laser welding of stainless steel and, particularly, on the behavior of the plasma plume in the welding process were investigated. According to the acoustic emission (AE) signals detected in the welding process, the possible mechanism for the improvement in penetration depth was discussed. The results indicated that the AE signals detected in the welding process reflected the behavior of the plasma plume as pulsed laser energy affecting the molten pool. The root-mean-square (RMS) waveform, AE count, and power spectrum of AE signals were three effective means to characterize the behavior of the plasma plume, which indicated the characteristics of energy released by the plasma plume. The activating flux affected by the laser beam helped to increase the duration and intensity of energy released by the plasma plume, which improved the recoil force and thermal effect transferred from the plasma plume to the molten pool. These results were the main mechanism for Cr2O3 activating flux addition improving the penetration depth in pulsed YAG laser welding.

  4. Characterization and Comparison of Aluminum, Silicon, and Carbon Laser Ablation Plumes

    Science.gov (United States)

    Iratcabal, Jeremy; Swanson, Kyle; Covington, Aaron

    2017-10-01

    Laser ablation of solid targets produces plasma plumes with rapidly evolving temperature and density gradients. These gradients can be measured using laser interferometric techniques that allow for the study of the plasma as the plume expands from the target surface and the temperature and density decrease. A systematic study of the temperature and density of aluminum, silicon, and carbon plasma plumes produced with a 2 TW/cm2 laser using spectroscopic, interferometric, fast imaging, and charge diagnostics will be presented. Carbon, aluminum, and silicon plumes are of interest because they are closely grouped on the periodic table but have very different material characteristics. Temporally and spatially resolved data was collected to characterize the evolution of the plasma in the plume. To probe the plasmas produced from these materials, optical spectroscopy was employed to identify and measure the temperature of the coexisting neutral and ionized atomic and molecular species. A Mach-Zehnder interferometer was employed to measure electron density. ICCD imaging and shadowgraphy were used to image the plume dynamics. A comparison of plasma evolution for each element will also be presented and will provide data to benchmark plasma codes. This work was supported by the University of Nevada, Reno, the U.S. DOE /NNSA Cooperative Agreement No. DE-NA0002075, and National Securities Technologies, LLC under Contract No. DE-AC52-06NA25946/Subcontract No. 165819.

  5. Emission features and expansion dynamics of nanosecond laser ablation plumes at different ambient pressures

    Science.gov (United States)

    Farid, N.; Harilal, S. S.; Ding, H.; Hassanein, A.

    2014-01-01

    The influence of ambient pressure on the spectral emission features and expansion dynamics of a plasma plume generated on a metal target has been investigated. The plasma plumes were generated by irradiating Cu targets using 6 ns, 1064 nm pulses from a Q-switched Nd:YAG laser. The emission and expansion dynamics of the plasma plumes were studied by varying air ambient pressure levels ranging from vacuum to atmospheric pressure. The ambient pressure levels were found to affect both the line intensities and broadening along with the signal to background and signal to noise ratios and the optimum pressure conditions for analytical applications were evaluated. The characteristic plume parameters were estimated using emission spectroscopy means and noticed that the excitation temperature peaked ˜300 Torr, while the electron density showed a maximum ˜100 Torr. Fast-gated images showed a complex interaction between the plume and background air leading to changes in the plume geometry with pressure as well as time. Surface morphology of irradiated surface showed that the pressure of the ambient gas affects the laser-target coupling significantly.

  6. Emission features and expansion dynamics of nanosecond laser ablation plumes at different ambient pressures

    Energy Technology Data Exchange (ETDEWEB)

    Farid, N. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Key Laboratory of Materials Modification by Laser, Ion and electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China); Harilal, S. S., E-mail: hari@purdue.edu; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Ding, H. [Key Laboratory of Materials Modification by Laser, Ion and electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China)

    2014-01-21

    The influence of ambient pressure on the spectral emission features and expansion dynamics of a plasma plume generated on a metal target has been investigated. The plasma plumes were generated by irradiating Cu targets using 6 ns, 1064 nm pulses from a Q-switched Nd:YAG laser. The emission and expansion dynamics of the plasma plumes were studied by varying air ambient pressure levels ranging from vacuum to atmospheric pressure. The ambient pressure levels were found to affect both the line intensities and broadening along with the signal to background and signal to noise ratios and the optimum pressure conditions for analytical applications were evaluated. The characteristic plume parameters were estimated using emission spectroscopy means and noticed that the excitation temperature peaked ∼300 Torr, while the electron density showed a maximum ∼100 Torr. Fast-gated images showed a complex interaction between the plume and background air leading to changes in the plume geometry with pressure as well as time. Surface morphology of irradiated surface showed that the pressure of the ambient gas affects the laser-target coupling significantly.

  7. Velocity and magnetic field measurements of Taylor plumes in SSX under different boundary conditions

    Science.gov (United States)

    Kaur, Manjit; Brown, M. R.; Han, J.; Shrock, J. E.; Schaffner, D. A.

    2016-10-01

    The SSX device has been modified by the addition of a 1 m long glass extension for accommodating pulsed theta pinch coils. The Taylor plumes are launched from a magnetized plasma gun and flow to an expansion volume downstream. The time of flight (TOF) measurements of these plumes are carried out using a linear array of Ḃ probes (separated by 10cm). TOF of the plasma plumes from one probe location to the next is determined by direct comparison of the magnetic field structures as well as by carrying out a cross-correlation analysis. With the glass boundary, the typical velocity of the Taylor plumes is found to be 25km /s , accompanied by a fast plasma (>= 50km /s) at the leading edge. Magnetic field embedded in the Taylor plumes is measured in the expansion chamber using a three-dimensional array of Ḃ probes and is found to be 700G . Some flux conservation of the Taylor plumes is provided by using a resistive (soak time 3 μs) and a mesh (soak time 170 μs > discharge time) liner around the glass tube for improving the downstream Taylor state velocity as well as the magnetic field. The results from these different boundary conditions will be presented. Work supported by DOE OFES and ARPA-E ALPHA programs.

  8. An experimental study on the near-source region of lazy turbulent plumes

    Science.gov (United States)

    Ciriello, Francesco; Hunt, Gary R.

    2017-11-01

    The near-source region of a `lazy' turbulent buoyant plume issuing from a circular source is examined for source Richardson numbers in the range of 101 to 107. New data is acquired for the radial contraction and streamwise variation of volume flux through an experimental programme of dye visualisations and particle image velocimetry. This data reveals the limited applicability of traditional entrainment laws used in integral modelling approaches for the description of the near-source region for these source Richardson numbers. A revised entrainment function is proposed, based on which we introduce a classification of plume behaviour whereby the degree of `laziness' may be expressed in terms of the excess dilution that occurs compared to a `pure' constant Richardson number plume. The increased entrainment measured in lazy plumes is attributed to Rayleigh-Taylor instabilities developing along the contraction of the plume which promote the additional engulfment of ambient fluid into the plume. This work was funded by an EPSRC Industial Case Award sponsored by Dyson Technology Ltd. Special thanks go to the members of the Dyson Environmental Control Group that regularly visit us in Cambridge for discussions about our work.

  9. Modeling the effect of plume-rise on the transport of carbon monoxide over Africa with NCAR CAM

    Directory of Open Access Journals (Sweden)

    H. Guan

    2008-11-01

    Full Text Available We investigated the effects of fire-induced plume-rise on the simulation of carbon monoxide (CO over Africa and its export during SAFARI 2000 using the NCAR Community Atmosphere Model (CAM with a CO tracer and a plume-rise parameterization scheme. The plume-rise parameterization scheme simulates the consequences of strong buoyancy of hot gases emitted from biomass burning, including both dry and cloud-associated (pyro-cumulus lofting. The current implementation of the plume-rise parameterization scheme into the global model provides an opportunity to examine the effect of plume-rise on long-range transport. The CAM simulation with the plume-rise parameterization scheme seems to show a substantial improvement of the agreements between the modeled and aircraft-measured vertical distribution of CO over Southern Africa biomass-burning area. The plume-rise mechanism plays a crucial role in lofting biomass-burning pollutants to the middle troposphere. In the presence of deep convection we found that the plume-rise mechanism results in a decrease of CO concentration in the upper troposphere. The plume-rise depletes the boundary layer, and thus leaves lower concentrations of CO to be lofted by the deep convection process. The effect of the plume-rise on free troposphere CO concentration is more important for the source area (short-distance transport than for remote areas (long-distance transport. A budget analysis of CO burden over Southern Africa reveals the plume-rise process to have a similar impact as the chemical production of CO by OH and CH4. In addition, the plume-rise process has an minor impact on the regional export. These results further confirm and extend previous findings in a regional model study. Effective lofting of large concentration of CO by the plume-rise mechanism also has implications for local air quality forecasting in areas affected by other fire-related pollutants.

  10. Modeling Macro- and Micro-Scale Turbulent Mixing and Chemistry in Engine Exhaust Plumes

    Science.gov (United States)

    Menon, Suresh

    1998-01-01

    Simulation of turbulent mixing and chemical processes in the near-field plume and plume-vortex regimes has been successfully carried out recently using a reduced gas phase kinetics mechanism which substantially decreased the computational cost. A detailed mechanism including gas phase HOx, NOx, and SOx chemistry between the aircraft exhaust and the ambient air in near-field aircraft plumes is compiled. A reduced mechanism capturing the major chemical pathways is developed. Predictions by the reduced mechanism are found to be in good agreement with those by the detailed mechanism. With the reduced chemistry, the computer CPU time is saved by a factor of more than 3.5 for the near-field plume modeling. Distributions of major chemical species are obtained and analyzed. The computed sensitivities of major species with respect to reaction step are deduced for identification of the dominant gas phase kinetic reaction pathways in the jet plume. Both the near field plume and the plume-vortex regimes were investigated using advanced mixing models. In the near field, a stand-alone mixing model was used to investigate the impact of turbulent mixing on the micro- and macro-scale mixing processes using a reduced reaction kinetics model. The plume-vortex regime was simulated using a large-eddy simulation model. Vortex plume behind Boeing 737 and 747 aircraft was simulated along with relevant kinetics. Many features of the computed flow field show reasonable agreement with data. The entrainment of the engine plumes into the wing tip vortices and also the partial detrainment of the plume were numerically captured. The impact of fluid mechanics on the chemical processes was also studied. Results show that there are significant differences between spatial and temporal simulations especially in the predicted SO3 concentrations. This has important implications for the prediction of sulfuric acid aerosols in the wake and may partly explain the discrepancy between past numerical studies

  11. Area 2: Inexpensive Monitoring and Uncertainty Assessment of CO2 Plume Migration using Injection Data

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, Sanjay [Univ. of Texas, Austin, TX (United States)

    2014-09-30

    In-depth understanding of the long-term fate of CO₂ in the subsurface requires study and analysis of the reservoir formation, the overlaying caprock formation, and adjacent faults. Because there is significant uncertainty in predicting the location and extent of geologic heterogeneity that can impact the future migration of CO₂ in the subsurface, there is a need to develop algorithms that can reliably quantify this uncertainty in plume migration. This project is focused on the development of a model selection algorithm that refines an initial suite of subsurface models representing the prior uncertainty to create a posterior set of subsurface models that reflect injection performance consistent with that observed. Such posterior models can be used to represent uncertainty in the future migration of the CO₂ plume. Because only injection data is required, the method provides a very inexpensive method to map the migration of the plume and the associated uncertainty in migration paths. The model selection method developed as part of this project mainly consists of assessing the connectivity/dynamic characteristics of a large prior ensemble of models, grouping the models on the basis of their expected dynamic response, selecting the subgroup of models that most closely yield dynamic response closest to the observed dynamic data, and finally quantifying the uncertainty in plume migration using the selected subset of models. The main accomplishment of the project is the development of a software module within the SGEMS earth modeling software package that implements the model selection methodology. This software module was subsequently applied to analyze CO₂ plume migration in two field projects – the In Salah CO₂ Injection project in Algeria and CO₂ injection into the Utsira formation in Norway. These applications of the software revealed that the proxies developed in this project for quickly assessing the dynamic characteristics of the reservoir were

  12. On the statistical significance of correlations between synthetic mantle plumes and tomographic models

    Science.gov (United States)

    Boschi, L.; Becker, Thorsten W.; Steinberger, Bernhard

    2008-04-01

    In a recent article, [Boschi, L., Becker, T.W., Steinberger, B., 2007. Mantle plumes: dynamic models and seismic images. Geochem. Geophys. Geosyst. 8, Q10006. doi:10.1029/2007GC001733] (BBS07) have re-evaluated the degree to which slow seismic tomography anomalies correlate with the possible locations of plume-like mantle upwellings connected to surface hotspots. They showed that several, but not all, hotspots are likely to have a deep mantle origin. Importantly, they found that when advection of plume conduits in mantle flow is considered, such correlations are significantly higher than when conduits are assumed to be vertical under hotspots. The validity of these statements depends, however, on the definition of statistical significance. BBS07 evaluated the significance of correlation through simple Student's t tests. Anderson (personal communication, July 2007) questioned this approach, given that the true information content of published tomography models is generally unknown, and proposed, instead, to evaluate the significance of correlation by comparing tomographic results with Monte Carlo simulations of randomly located plumes. Following this approach, we show here that the correlation found by BBS07 between advected plumes and slow anomalies in S-velocity tomography is less significant than previously stated, but still significant (at the 99.7% confidence level). We also find an indication that the seismic/geodynamic correlation observed by BBS07 does not only reflect the natural tendency of plumes to cluster in slow/hot regions of the mantle: although realistically advected, and thereby biased towards such regions, our random plumes correlate with slow tomographic anomalies significantly less than the plume models of BBS07. A less significant correlation with plume models characterizes P-velocity tomography; the correlation is, however, enhanced, if flow is computed from tomographic models with amplified heterogeneity, possibly accounting for the known

  13. Vertical structure of the phytoplankton community associated with a coastal plume in the Gulf of Mexico

    Science.gov (United States)

    Wawrik, B.; Paul, J.H.; Campbell, L.; Griffin, D.; Houchin, L.; Fuentes-Ortega, A.; Muller-Karger, F.

    2003-01-01

    Low salinity plumes of coastal origin are occasionally found far offshore, where they display a distinct color signature detectable by satellites. The impact of such plumes on carbon fixation and phytoplankton community structure in vertical profiles and on basin wide scales is poorly understood. On a research cruise in June 1999, ocean-color satellite-images (Sea-viewing Wide Field-of-view Sensor, SeaWiFS) were used in locating a Mississippi River plume in the eastern Gulf of Mexico. Profiles sampled within and outside of the plume were analyzed using flow cytometry, HPLC pigment analysis and primary production using 14C incorporation. Additionally, RubisCO large subunit (rbcL) gene expression was measured by hybridization of extracted RNA using 3 full-length RNA gene probes specific for individual phytoplankton clades. We also used a combination of RT-PCR/PCR and TA cloning in order to generate cDNA and DNA rbcL clone libraries from samples taken in the plume. Primary productivity was greatest in the low salinity surface layer of the plume. The plume was also associated with high Synechococcus counts and a strong peak in Form IA rbcL expression. Form IB rbcL (green algal) mRNA was abundant at the subsurface chlorophyll maximum (SCM), whereas Form ID rbcL (chromophytic) expression showed little vertical structure. Phylogenetic analysis of cDNA libraries demonstrated the presence of Form IA rbcL Synechococcus phylotypes in the plume. Below the plume, 2 spatially separated and genetically distinct rbcL clades of Prochlorococcus were observed. This indicated the presence of the high- and low-light adapted clades of Prochlorococcus. A large and very diverse clade of Prymnesiophytes was distributed throughout the water column, whereas a clade of closely related prasinophytes may have dominated at the SCM. These data indicate that the Mississippi river plume may dramatically alter the surface picoplankton composition of the Gulf of Mexico, with Synechococcus displacing

  14. Tritium plume dynamics in the shallow unsaturated zone in an arid environment

    Science.gov (United States)

    Maples, S.R.; Andraski, B.J.; Stonestrom, D.A.; Cooper, C.A.; Pohll, G.; Michel, R.L.

    2014-01-01

    The spatiotemporal variability of a tritium plume in the shallow unsaturated zone and the mechanisms controlling its transport were evaluated during a 10-yr study. Plume movement was minimal and its mass declined by 68%. Upward-directed diffusive-vapor tritium fluxes and radioactive decay accounted for most of the observed plume-mass declines. Effective isolation of tritium (3H) and other contaminants at waste-burial facilities requires improved understanding of transport processes and pathways. Previous studies documented an anomalously widespread (i.e., theoretically unexpected) distribution of 3H (>400 m from burial trenches) in a dry, sub-root-zone gravelly layer (1–2-m depth) adjacent to a low-level radioactive waste (LLRW) burial facility in the Amargosa Desert, Nevada, that closed in 1992. The objectives of this study were to: (i) characterize long-term, spatiotemporal variability of 3H plumes; and (ii) quantify the processes controlling 3H behavior in the sub-root-zone gravelly layer beneath native vegetation adjacent to the facility. Geostatistical methods, spatial moment analyses, and mass flux calculations were applied to a spatiotemporally comprehensive, 10-yr data set (2001–2011). Results showed minimal bulk-plume advancement during the study period and limited Fickian spreading of mass. Observed spreading rates were generally consistent with theoretical vapor-phase dispersion. The plume mass diminished more rapidly than would be expected from radioactive decay alone, indicating net efflux from the plume. Estimates of upward 3H efflux via diffusive-vapor movement were >10× greater than by dispersive-vapor or total-liquid movement. Total vertical fluxes were >20× greater than lateral diffusive-vapor fluxes, highlighting the importance of upward migration toward the land surface. Mass-balance calculations showed that radioactive decay and upward diffusive-vapor fluxes contributed the majority of plume loss. Results indicate that plume losses

  15. Remote Sensing of Volcanic Clouds: Sulfur Gases and Plume Top Topography

    Science.gov (United States)

    Crisp, Joy A.

    1999-01-01

    New absorption line parameters for H2S were published and submitted to the Gestion et Etude des Informations Spectroscopiques Atmospheriques (GEISA) and high resolution transmission molecular absorption (HITRAN) databases. These new absorption line parameters will make it possible to use observations from the future Tropospheric Emission Spectrometer (TES) instrument [Earth Observing System (EOS) Chemistry Mission (CHEM) platform] to make more accurate H2S measurements if it observes an H2S-rich volcanic cloud. H2S is the second most abundant volcanic sulfur gas, and like SO2, it also converts to H2SO4 aerosols and can have a climate impact. A paper on the Moderate-resolution Imaging-Spectroradiometer (MODIS) SO2 alert is being revised. New aspects in the revision include verification of the SO2 alert during the EOS mission; factors affecting SO2 detection at thermal infrared, ultraviolet, and microwave wavelengths; radiative transfer tests; more description of satellite instruments; and thermal surface alert installed for MODIS. Her research involves the use of remote sensing to generate maps of plume top altitude. This parameter is important for models of volcanic eruption, aircraft hazards, and climate impact. The topographic shape of the top surface of a volcanic plume can provide information necessary to understand the physics controlling the injection and dispersal of a volcanic plume in the atmosphere. Glaze et al. describe the application of a photoclinometric technique to volcanic plumes. The software algorithm has been improved to account for more general plume and illumination geometries and for easily extracting position information directly from Advanced Very High-Resolution Radiometer (AVHRR) level 1B data. Testing of the algorithm has focused on acquiring AVHRR data for a variety of volcanic plumes in an effort to identify problems with the software as well as model sensitivities. The plumes chosen were erupted from volcanoes at a variety of

  16. OClO and BrO observations in the volcanic plume of Mt. Etna - implications on the chemistry of chlorine and bromine species in volcanic plumes

    Science.gov (United States)

    Gliß, J.; Bobrowski, N.; Vogel, L.; Platt, U.

    2014-10-01

    Spatial and temporal profiles of chlorine dioxide (OClO), bromine monoxide (BrO) and sulphur dioxide (SO2) were measured in the plume of Mt. Etna, Italy, in September 2012 using Multi-Axis-Differential-Optical-Absorption-Spectroscopy (MAX-DOAS). OClO (BrO) was detected in 119 (452) individual measurements covering plume ages up to 6 (23) minutes. The retrieved slant column densities (SCDs) reached values up to 2.0 × 1014 molecules cm-2 (OClO) and 1.1 × 1015 molecules cm-2 (BrO). In addition, the spectra were analysed for signatures of IO, OIO and OBrO, none of these species could be detected. The corresponding detection limits for IO / SO2, OIO / SO2 and OBrO / SO2 were 1.8 × 10-6, 2.0 × 10-5 and 1.1 × 10-5 respectively. The measurements were performed at plume ages (τ) from zero to 23 min downwind the emission source. The chemical variability of BrO and OClO in the plume was studied analysing the OClO / SO2 and BrO / SO2-ratio. A marked increase of both ratios was observed in the young plume (τ 3 min) with mean abundances of 3.17 × 10-5 (OClO / SO2), 1.55 × 10-4 (BrO / SO2) and 0.16 (OClO / BrO). Furthermore, enhanced BrO/SO2-ratios were found at the plume edges (by ~30-37%) and a strong indication of enhanced OClO / SO2-ratios as well (~10-250%). A measurement performed in the early morning (05:20-06:20 UTC, sunrise: 04:40 UTC) showed an BrO / SO2-ratio increasing with time until 05:35 UTC and a constant ratio afterwards. Observing this increase was only possible due to a correction for stratospheric BrO signals in the plume spectra. The corresponding OClO / SO2-ratio showed a similar trend stabilising around 06:13 UTC, approximately 40 min later than BrO. This is another strong indication for the photochemical nature of the reactions involved in the formation of oxidised halogens in volcanic plumes. In particular, these findings support the current understanding of the underlying chemistry, namely, that BrO is formed in an autocatalytic reaction

  17. Volcanic Plume Elevation Model Derived From Landsat 8: examples on Holuhraun (Iceland) and Mount Etna (Italy)

    Science.gov (United States)

    de Michele, Marcello; Raucoules, Daniel; Arason, Þórður; Spinetti, Claudia; Corradini, Stefano; Merucci, Luca

    2016-04-01

    The retrieval of both height and velocity of a volcanic plume is an important issue in volcanology. As an example, it is known that large volcanic eruptions can temporarily alter the climate, causing global cooling and shifting precipitation patterns; the ash/gas dispersion in the atmosphere, their impact and lifetime around the globe, greatly depends on the injection altitude. Plume height information is critical for ash dispersion modelling and air traffic security. Furthermore, plume height during explosive volcanism is the primary parameter for estimating mass eruption rate. Knowing the plume altitude is also important to get the correct amount of SO2 concentration from dedicated spaceborne spectrometers. Moreover, the distribution of ash deposits on ground greatly depends on the ash cloud altitude, which has an impact on risk assessment and crisis management. Furthermore, a spatially detailed plume height measure could be used as a hint for gas emission rate estimation and for ash plume volume researches, which both have an impact on climate research, air quality assessment for aviation and finally for the understanding of the volcanic system itself as ash/gas emission rates are related to the state of pressurization of the magmatic chamber. Today, the community mainly relies on ground based measurements but often they can be difficult to collect as by definition volcanic areas are dangerous areas (presence of toxic gases) and can be remotely situated and difficult to access. Satellite remote sensing offers a comprehensive and safe way to estimate plume height. Conventional photogrammetric restitution based on satellite imagery fails in precisely retrieving a plume elevation model as the plume own velocity induces an apparent parallax that adds up to the standard parallax given by the stereoscopic view. Therefore, measurements based on standard satellite photogrammeric restitution do not apply as there is an ambiguity in the measurement of the plume position

  18. Contaminant plume configuration and movement: an experimental model

    Science.gov (United States)

    Alencoao, A.; Reis, A.; Pereira, M. G.; Liberato, M. L. R.; Caramelo, L.; Amraoui, M.; Amorim, V.

    2009-04-01

    The relevance of Science and Technology in our daily routines makes it compulsory to educate citizens who have both scientific literacy and scientific knowledge. These will allow them to be intervening citizens in a constantly changing society. Thus, physical and natural sciences are included in school curricula, both in primary and secondary education, with the fundamental aim of developing in the students the skills, attitudes and knowledge needed for the understanding of the planet Earth and its real problems. On the other hand, teaching in Geosciences is more and more based on practical methodologies which use didactic material, sustaining teachers' pedagogical practices and facilitating students' learning tasks suggested on the syllabus defined for each school level. Themes related to exploring the different components of the Hydrological Cycle and themes related to natural environment protection and preservation, namely water resources and soil contamination by industrial and urban sewage are examples of subject matters included on the Portuguese syllabus. These topics motivated the conception and construction of experimental models for the study of the propagation of pollutants on a porous medium. The experimental models allow inducing a horizontal flux of water though different kinds of permeable substances (e.g. sand, silt), with contamination spots on its surface. These experimental activities facilitate the student to understand the flow path of contaminating substances on the saturated zone and to observe the contaminant plume configuration and movement. The activities are explored in a teaching and learning process perspective where the student builds its own knowledge through real question- problem based learning which relate Science, Technology and Society. These activities have been developed in the framework of project ‘Water in the Environment' (CV/PVI/0854) of the POCTI Program (Programa Operacional "Ciência, Tecnologia, Inovação") financed

  19. REMOTE DETECTION OF RADIOACTIVE PLUMES USING MILLIMETER WAVE TECHNOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Barnowski, R.; Chien; H.; Gopalsami, N.

    2009-01-01

    The reprocessing of spent nuclear fuel, a common method for manufacturing weapons-grade special nuclear materials, is accompanied by the release of fi ssion products trapped within the fuel. One of these fi ssion products is a radioactive isotope of Krypton (Kr-85); a pure β- emitter with a half-life of 10.72 years. Due to its chemical neutrality and relatively long half life, nearly all of the Kr-85 is released into the surrounding air during reprocessing, resulting in a concentration of Kr-85 near the source that is several orders of magnitude higher than the typical background (atmospheric) concentrations. This high concentration of Kr-85 is accompanied by a proportionately high increase in air ionization due to the release of beta radiation from Kr-85 decay. Millimeter wave (MMW) sensing technology can be used to detect the presence of Kr-85 induced plumes since a high concentration of ions in the air increases the radar cross section due to a combination of atmospheric phenomena. Possible applications for this technology include the remote sensing of reprocessing activities across national borders bolstering global anti-proliferation initiatives. The feasibility of using MMW radar technology to uniquely detect the presence of Kr-85 can be tested using commercial ion generators or sealed radioactive sources in the laboratory. In this paper we describe our work to derive an ion dispersion model that will describe the spatial distribution of ions from Kr-85 and other common lab sources. The types and energies of radiation emitted by isotopes Co-60 and Cs-137 were researched, and these parameters were incorporated into these dispersion models. Our results can be compared with the results of MMW detection experiments in order to quantify the relationship between radar cross section and air ionization as well as to further calibrate the MMW detection equipment.

  20. The effect of fine particles on ash cloud and plume dynamics

    Science.gov (United States)

    Jessop, D.; Jellinek, M.

    2013-12-01

    Powerful explosive volcanic eruptions produce turbulent, buoyant plumes that inject ash high into the atmosphere, which spread as gravity currents to form umbrella clouds. The transport, dispersion and sedimentation of ash within these flows are key physical processes influencing the dynamics, stability and longevity of umbrella clouds. Understanding the underlying mechanics at work is, consequently, crucial for assessing volcanic hazards as well as the nature of volcanic forcings on climate. State-of-the-art models applied to predict the evolution of the plumes and umbrella clouds must include effects related to both particle-particle and particle-fluid momentum exchanges, which are complex and poorly understood. Particles suspended in both the plume and umbrella cloud modify the intensity of the turbulence. This has a knock-on effect on the entrainment of fluid into the flows, and hence the mass and buoyancy fluxes that ultimately drive the spread of the cloud. Accordingly, we investigate the effect of polydisperse particle distributions on the plume and cloud dynamics. In particular, we look at how the presence of fine particles (ash, pumice or aerosol particles) affect the longevity of the umbrella cloud, and how re-entrainment of particles of all sizes leads to instability of the cloud. Our investigation involves laboratory experiments where a particle/water mixture is injected into a density-stratified environment. The results of our experiments are used to inform a simple axisymmetric forced-plume model. Despite its simplicity, the model is capable of predicting the onset of instability as a function of the source conditions. Early dynamics of umbrella cloud formation as the spreading of a particle-laden plume at it's neutrally buoyant level. Experimental plume showing turbulent structure and onset of sedimentation.

  1. Genome-resolved metagenomics reveals that sulfur metabolism dominates the microbial ecology of rising hydrothermal plumes

    Science.gov (United States)

    Anantharaman, K.; Breier, J. A., Jr.; Jain, S.; Reed, D. C.; Dick, G.

    2015-12-01

    Deep-sea hydrothermal plumes occur when hot fluids from hydrothermal vents replete with chemically reduced elements and compounds like sulfide, methane, hydrogen, ammonia, iron and manganese mix with cold, oxic seawater. Chemosynthetic microbes use these reduced chemicals to power primary production and are pervasive throughout the deep sea, even at sites far removed from hydrothermal vents. Although neutrally-buoyant hydrothermal plumes have been well-studied, rising hydrothermal plumes have received little attention even though they represent an important interface in the deep-sea where microbial metabolism and particle formation processes control the transformation of important elements and impact global biogeochemical cycles. In this study, we used genome-resolved metagenomic analyses and thermodynamic-bioenergetic modeling to study the microbial ecology of rising hydrothermal plumes at five different hydrothermal vents spanning a range of geochemical gradients at the Eastern Lau Spreading Center (ELSC) in the Western Pacific Ocean. Our analyses show that differences in the geochemistry of hydrothermal vents do not manifest in microbial diversity and community composition, both of which display only minor variance across ELSC hydrothermal plumes. Microbial metabolism is dominated by oxidation of reduced sulfur species and supports a diversity of bacteria, archaea and viruses that provide intriguing insights into metabolic plasticity and virus-mediated horizontal gene transfer in the microbial community. The manifestation of sulfur oxidation genes in hydrogen and methane oxidizing organisms hints at metabolic opportunism in deep-sea microbes that would enable them to respond to varying redox conditions in hydrothermal plumes. Finally, we infer that the abundance, diversity and metabolic versatility of microbes associated with sulfur oxidation impart functional redundancy that could allow it to persist in the dynamic settings of hydrothermal plumes.

  2. Modelling plume dispersion pattern from a point source using spatial auto-correlational analysis

    Science.gov (United States)

    Ujoh, F.; Kwabe, D.

    2014-02-01

    The main objective of the study is to estimate the rate and model the pattern of plume rise from Dangote Cement Plc. A handheld Garmin GPS was employed for collection of coordinates at a single kilometre graduation from the centre of the factory to 10 kilometres. Plume rate was estimated using the Gaussian model while Kriging, using ArcGIS, was adopted for modelling the pattern of plume dispersion over a 10 kilometre radius around the factory. ANOVA test was applied for statistical analysis of the plume coefficients. The results indicate that plume dispersion is generally high with highest values recorded for the atmospheric stability classes A and B, while the least values are recorded for the atmospheric stability classes F and E. The variograms derived from the Kriging reveal that the pattern of plume dispersion is outwardly radial and omni-directional. With the exception of 3 stability sub-classes (DH, EH and FH) out of a total of 12, the 24-hour average of particulate matters (PM10 and PM2.5) within the study area is outrageously higher (highest value at 21392.3) than the average safety limit of 150 ug/m3 - 230 ug/m3 prescribed by the 2006 WHO guidelines. This indicates the presence of respirable and non-respirable pollutants that create poor ambient air quality. The study concludes that the use of geospatial technology can be adopted in modelling dispersion of pollutants from a point source. The study recommends ameliorative measures to reduce the rate of plume emission at the factory.

  3. Review of quantitative surveys of the length and stability of MTBE, TBA, and benzene plumes in groundwater at UST sites.

    Science.gov (United States)

    Connor, John A; Kamath, Roopa; Walker, Kenneth L; McHugh, Thomas E

    2015-01-01

    Quantitative information regarding the length and stability condition of groundwater plumes of benzene, methyl tert-butyl ether (MTBE), and tert-butyl alcohol (TBA) has been compiled from thousands of underground storage tank (UST) sites in the United States where gasoline fuel releases have occurred. This paper presents a review and summary of 13 published scientific surveys, of which 10 address benzene and/or MTBE plumes only, and 3 address benzene, MTBE, and TBA plumes. These data show the observed lengths of benzene and MTBE plumes to be relatively consistent among various regions and hydrogeologic settings, with median lengths at a delineation limit of 10 µg/L falling into relatively narrow ranges from 101 to 185 feet for benzene and 110 to 178 feet for MTBE. The observed statistical distributions of MTBE and benzene plumes show the two plume types to be of comparable lengths, with 90th percentile MTBE plume lengths moderately exceeding benzene plume lengths by 16% at a 10-µg/L delineation limit (400 feet vs. 345 feet) and 25% at a 5-µg/L delineation limit (530 feet vs. 425 feet). Stability analyses for benzene and MTBE plumes found 94 and 93% of these plumes, respectively, to be in a nonexpanding condition, and over 91% of individual monitoring wells to exhibit nonincreasing concentration trends. Three published studies addressing TBA found TBA plumes to be of comparable length to MTBE and benzene plumes, with 86% of wells in one study showing nonincreasing concentration trends. © 2014 GSI Environmental Inc. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association.

  4. Investigation of the vapour-plasma plume in the welding of titanium by high-power ytterbium fibre laser radiation

    Science.gov (United States)

    Bykovskiy, D. P.; Petrovskii, V. N.; Uspenskiy, S. A.

    2015-03-01

    The vapour-plasma plume produced in the welding of 6-mm thick VT-23 titanium alloy plates by ytterbium fibre laser radiation of up to 10 kW power is studied in the protective Ar gas medium. High-speed video filming of the vapour-plasma plume is used to visualise the processes occurring during laser welding. The coefficient of inverse bremsstrahlung by the welding plasma plume is calculated from the data of the spectrometric study.

  5. Dynamics of a vertical turbulent plume in a stratification typical of Greenland fjords: an idealized model of subglacial discharge

    Science.gov (United States)

    Stenberg, Erik; Ezhova, Ekaterina; Cenedese, Claudia; Brandt, Luca

    2017-04-01

    We the report results of large eddy simulations of a turbulent buoyant plume in a configuration providing an idealized model of subglacial discharge from a submarine glacier in stratifications typical of Greenland Fjords. We neglect a horizontal momentum of the plume and assume that its influence on the plume dynamics is small and important only close to the source. Moreover, idealized models have considered the plume adjacent to the glacier as a half-conical plume (e.g., [1]). Thus, to compare the results for such plume with the classical plume theory, developed for free plumes entraining ambient fluid from all directions, it is convenient to add the second half-conical part and consider a free plume with double the total discharge as a model. Given the estimate of the total subglacial discharge for Helheim Glacier in Sermilik Fjord [2], we perform simulations with double the total discharge in order to investigate the dynamics of the flow in typical winter and summer stratifications in Greenland fjords [3]. The plume is discharged from a round source of various diameters. In winter, when the stratification is similar to an idealised two-layers case, turbulent entrainment and generation of internal waves by the plume top are in agreement with the theoretical and numerical results obtained for turbulent jets in a two-layer stratification. In summer, instead, the stratification is more complex and turbulent entrainment is significantly reduced. The subsurface layer in summer is characterized by a strong density gradient and the oscillating plume generates non-linear internal waves which are able to mix this layer even if the plume does not penetrate to the surface. The classical theory for the integral parameters of a turbulent plume in a homogeneous fluid gives accurate predictions of the plume parameters in the weakly stratified lower layer up to the pycnocline. [1] Mankoff, K. D., F. Straneo, C. Cenedese, S. B. Das, C. D. Richards, and H. Singh, 2016: Structure

  6. The LCROSS Ejecta Plume Revealed: First Characterization from Earth-based Imaging

    Science.gov (United States)

    Miller, C.; Chanover, N.; Hermalyn, B.; Strycker, P. D.; Hamilton, R. T.; Suggs, R. M.

    2012-12-01

    On October 9, 2009, the Lunar Crater Observation and Sensing Satellite (LCROSS) struck the floor of Cabeus crater. We observed the LCROSS impact site at 0.5-second intervals throughout the time of impact in the V-band (491 to 591 nm) using the Agile camera on the 3.5 m telescope at the Apache Point Observatory. Our initial analysis of these images showed that the ejecta plume could be no brighter than 9.5 magnitudes/arcsec^2. (Chanover et al. 2011, JGR). We subsequently applied a Principal Component Analysis (PCA) technique to filter out time-varying seeing distortions and image registration errors from an 8-minute sequence of images centered on the LCROSS impact time and unambiguously detected the evolving plume below the noise threshold. This is the first and only reported image detection of the LCROSS plume from ground-based instruments. Our detection is consistent with an ejecta plume that reaches peak brightness between 12 and 20 seconds after impact and fades to an undetectable level within 90 seconds after impact. This is consistent with in situ observations made by the LCROSS Shepherding Satellite (LCROSS S/SC) and the Lunar Reconnaissance Orbiter (LRO) that observed the impact from above (Colaprete et al., and Hayne et. al., 2010, Science). To test our detection method, we compared the brightness profiles derived from our impact image sequence to those extracted from a sequence with a simulated ejecta pattern. We performed 3-D ballistic simulations of trial impacts, starting with initial particle ejection angles and velocities derived from laboratory measurements made with the NASA Ames Vertical Gun of impacts of hollow test projectiles (Hermalyn et. al., 2012, Icarus). We extracted images from these simulations at 0.5-second intervals, combined them with a computer generated lunar landscape, and introduced image distortions due to time-varying seeing conditions and instrumental noise sources to produce a synthetic ejecta image sequence. We then re

  7. Active Plumes on Venus and Constraints on Mantle Viscosity and Volatile History

    Science.gov (United States)

    Smrekar, S. E.; Sotin, C.; Tom, H.; Bonaccorso, A.

    2011-12-01

    The interpretation of high emissivity anomalies in the Venus Express VIRTIS data set as indicating recent volcanism corroborates the presence of an active plumes inferred from gravity and topography. This study examines the number of plumes formed at the core-mantle boundary, their characteristics, and the predicted amount of partial melt using 3D spherical simulations with large viscosities variations and internal heating. We attempt to constrain the balance between internal heating (Hs), temperature difference across the mantle (ΔT), and mantle viscosity (ηs) needed to produce ~10 plumes globally. We have examined 16 cases with ΔT of 1140 to 2280°K, Hs of 0-10, and ηs of 10^20-10^21 Pa s. The equivalent activation energy is ~485 kJ/mole. Convective Rayleigh numbers range from 1e5 to 3e7. The case that produces the smallest number of hot plumes (21 globally) also predicts wet melting. This case has no internal heating, a mantle viscosity of 10^21 Pa s, and a ΔT of 1446°K. Although, cases without internal heating are not realistic, increasing internal heating increases the number of hot plumes. The limit occurs when the mantle temperature becomes so large that the temperature difference across the hot thermal boundary layer drops below the viscous temperature scale (Grasset and Parmentier, 1998), at which point there is insufficient buoyancy to give rise to plumes. Including a lower mantle viscosity value of 10^20 Pa s allows for larger values of internal heating with out shutting off hot plumes. This is consistent with a hotter mantle due to the presence of a stagnant lid. Alternatively, if the mantle is heating up due to the stagnant lid, the effect is equivalent to having lower rates of internal heating. In half of the cases, the hot plumes produce pressure release melting over several 100s km in the upper mantle, intersecting the wet solidus, but not the dry solidus. The only case that produces dry melting has a very high temperature difference of 2280

  8. Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic

    Directory of Open Access Journals (Sweden)

    E. Real

    2008-12-01

    Full Text Available The photochemical evolution of an anthropogenic plume from the New-York/Boston region during its transport at low altitudes over the North Atlantic to the European west coast has been studied using a Lagrangian framework. This plume, originally strongly polluted, was sampled by research aircraft just off the North American east coast on 3 successive days, and then 3 days downwind off the west coast of Ireland where another aircraft re-sampled a weakly polluted plume. Changes in trace gas concentrations during transport are reproduced using a photochemical trajectory model including deposition and mixing effects. Chemical and wet deposition processing dominated the evolution of all pollutants in the plume. The mean net photochemical O3 production is estimated to be −5 ppbv/day leading to low O3 by the time the plume reached Europe. Model runs with no wet deposition of HNO3 predicted much lower average net destruction of −1 ppbv/day O3, arising from increased levels of NOx via photolysis of HNO3. This indicates that wet deposition of HNO3 is indirectly responsible for 80% of the net destruction of ozone during plume transport. If the plume had not encountered precipitation, it would have reached Europe with O3 concentrations of up to 80 to 90 ppbv and CO between 120 and 140 ppbv. Photochemical destruction also played a more important role than mixing in the evolution of plume CO due to high levels of O3 and water vapour showing that CO cannot always be used as a tracer for polluted air masses, especially in plumes transported at low altitudes. The results also show that, in this case, an increase in O3/CO slopes can be attributed to photochemical destruction of CO and not to photochemical O3 production as is often assumed.

  9. Application of NIR Laser Spectroscopy to the Monitoring of Volcanic Plumes: Principles and Practicalities

    Science.gov (United States)

    Hamish, A.; Christenson, B. W.; Mazot, A.

    2014-12-01

    The major volatile species in volcanic plume emissions (i.e., H2O, CO2, SO2, HCl, HF) are all strongly infrared (IR)-active, and lend themselves to infrared spectroscopic analysis. However, physical/optical access to plume gases along pathways which include a suitable natural or active IR radiation source is often difficult or impossible to achieve, particularly for timeframes extending beyond short campaign periods. In this study, we present results from preliminary tests conducted on three volcanic CO2 plume emissions using a tunable diode NIR laser system (TDL, Boreal Laser Inc.). The approach is proving itself as a good candidate for continuous monitoring of volcanic plume CO2, and by default all other IR-active constituents for which lasers of appropriate wavelength are available. The CO2 system is configured with a TDL in a transceiver generating laser light which can be tuned to coincide with one of several absorption lines in the CO2 absorption band between 1575 nm and 1585 nm. This beam propagates through the atmosphere (and plume) to a retro-reflector, which returns the beam to a photodiode detector in the transceiver which processes the signal to report real time CO2 column densities. The CO2 absorption line at 1579.1 nm was used to good effect on Mt Ruapehu (NZ) where volcanic gases emanate through a 100 m deep crater lake, resulting in CO2 concentrations of > 78 ppm above background in the mixing zone varying from 4 to 30 m above the lake surface. Subsequent tests on the main plume at White Island, however, generated only poor results with indicated CO2 amounts being less than atmospheric. We concluded that this was the result of interference from a neighboring but comparatively minor H2O absorption band which in the proximal, higher temperature plume (estimated 50-70 °C), had H2O concentrations some 4-5 times greater than ambient. A change to a less sensitive absorption line further removed from potential H2O band interference (1567.9 nm) appears to

  10. Water quality, seasonality, and trajectory of an aquaculture-wastewater plume in the Red Sea

    KAUST Repository

    Hozumi, Aya

    2017-12-28

    As aquaculture activity increases globally, understanding water mass characteristics of the aquaculture-wastewater plume, its nutrients, and its organic matter load and spatial distribution in the coastal recipient, is critical to develop a more sustainable aquaculture operation and to improve coastal management. We examined wastewater (estimated 42-48 m3 s-1) discharged from the largest aquaculture facility in the Red Sea and surveyed the area around the aquaculture outfall to characterize the biogeochemical properties of the wastewater plume and its spatial distribution. In addition, we assessed its associated microbial community structure. The plume was characterized by elevated levels of salinity, density, and turbidity, and traveled along paths determined by the bathymetry to form a dense, 1-3 m thick layer above the seafloor. The effluent was observed at least 3.8 km from the outfall throughout the year, but up to 8 km in early autumn. The total nitrogen concentration in the plume was more than 4 times higher than in surface waters 1.4 km from the outfall. High-throughput sequencing data revealed that bacterial and cyanobacterial communities significantly differed, and flow cytometry results showed that total cell counts were significantly higher at the outfall. Arcobacter, a genus associated with opportunistic pathogenic species (e.g. A. butzleri), was more abundant, while Prochlorococcus sp. was significantly less abundant at the outfall. This dense, bottom-flowing plume may have a detrimental impact on benthic and demersal communities.

  11. Prediction of the volume flux of the thermal plume above a sitting person

    DEFF Research Database (Denmark)

    Zukowska, Daria; Popiolek, Zbigniew J.; Melikov, Arsen Krikor

    2009-01-01

    space. The plume volume flux, V, can be calculated based on the following equation: V = kv*Qexp(1/3)*(zt-zv)exp(5/3). In the equation zt is the distance from the measuring plane to the top of the heat source and Qc is the convective part of the heat loss. A value of the entrainment coefficient, kv......The paper presents a verification of a relatively simple method of volume flux calculation applied to the asymmetrical thermal plume generated by a sitting person in a condition of an upward piston flow. The method is based on a model of a thermal plume above a point heat source in an unbounded......, equal to 0.006 was used. The position of the virtual origin of the plume to the heat source top, zv, was optimized for seven different cases of thermal plumes above a sitting thermal manikin and the best agreement between the measured and calculated volume fluxes, not exceeding ±20%, was obtained for zv...

  12. Calculation of smoke plume mass from passive UV satellite measurements by GOME-2 polarization measurement devices

    Science.gov (United States)

    Penning de Vries, M. J. M.; Tuinder, O. N. E.; Wagner, T.; Fromm, M.

    2012-04-01

    The Wallow wildfire of 2011 was one of the most devastating fires ever in Arizona, burning over 2,000 km2 in the states of Arizona and New Mexico. The fire originated in the Bear Wallow Wilderness area in June, 2011, and raged for more than a month. The intense heat of the fire caused the formation of a pyro-convective cloud. The resulting smoke plume, partially located above low-lying clouds, was detected by several satellite instruments, including GOME-2 on June 2. The UV Aerosol Index, indicative of aerosol absorption, reached a maximum of 12 on that day, pointing to an elevated plume with moderately absorbing aerosols. We have performed extensive model calculations assuming different aerosol optical properties to determine the total aerosol optical depth of the plume. The plume altitude, needed to constrain the aerosol optical depth, was obtained from independent satellite measurements. The model results were compared with UV Aerosol Index and UV reflectances measured by the GOME-2 polarization measurement devices, which have a spatial resolution of roughly 10x40 km2. Although neither the exact aerosol optical properties nor optical depth can be obtained with this method, the range in aerosol optical depth values that we calculate, combined with the assumed specific extinction mass factor of 5 m2/kg lead us to a rough estimate of the smoke plume mass that cannot, at present, be assessed in another way.

  13. Velocity and Vorticity Fields of a Turbulent Plume under different experimental conditions

    Science.gov (United States)

    Matulka, A. M.; Gonzalez-Nieto, P. L.; Redondo, J. M.; Tarquis, A. M.

    2012-04-01

    The geophysical and practical importance and the applications of turbulent plumes as generators of strong dispersion processes are clearly recognized. In geophysics and astrophysics, it is usual to model as a jet or plume the generation mechanism of turbulent mixing as a part of a dispersion process [1-3]. An interesting geophysical problem is the study of volcanic plumes [2], which are columns of hot volcanic ash and gas emitted into the atmosphere during an explosive volcanic eruption. Another interesting like-plume phenomenon can be observed where a stream, usually a river, empties into a lake, sea or ocean, generating a river plume [3,4]. Turbulent plumes are fluid motions whose primary source of kinetic energy and momentum flux is due to body forces that arise from density inhomogeneities. The plume boundary acts as an interface across which ambient fluid is entrained, and the plume boundary moves at the velocity of the plume fluid. The difference between the plume-fluid radial velocity and the total fluid velocity quantifies in a natural way the purely horizontal entrainment flux of ambient fluid into the plume across the phase boundary at the plume edge [5,6]. We show some results of research on a single turbulent plume as well as on the structure of the interaction between different plumes and jets, We measure and compare velocity and vorticity fields occurring in different experimental configurations (Parametrized by the Atwood number and the initial potential energy as well as the Plume-Jet length scale). This work is based on experiments that have been performed in GFD laboratories (IPD and UPC) using visualizations methods (LIF,PIV) and advanced multiscaling techniques. We calculate velocity and vorticity PDFs and the evolution of the structure of stratified decaying, with DigFlow and Imacalc programs (Matulka 2010)[7], where video sequence processing provides a range of global and local descriptor features designed specifically for analysing fluid

  14. Ion trapping by dust grains: Simulation applications to the Enceladus plume

    Science.gov (United States)

    Farrell, W. M.; Wahlund, J.-E.; Morooka, M.; Kurth, W. S.; Gurnett, D. A.; MacDowall, R. J.

    2017-04-01

    Using a particle-in-cell electrostatic simulation, we examine the conditions that allow low-energy ions, like those produced in the Enceladus plume, to be attracted and trapped within the sheaths of negatively charged dust grains. The conventional wisdom is that all new ions produced in the Enceladus plume are free to get picked up (i.e., accelerated by the local E field to then undergo vB acceleration). However, we suggest herein that the presence of submicron-charged dust in the plume impedes this pickup process since the local grain electric field greatly exceeds the corotation E fields. The simulations demonstrate that cold ions will tend to accelerate toward the negatively charged grains and become part of the ion plasma sheath. These trapped ions will move with the grains, exiting the plume region at the dust speed. We suggest that Cassini's Langmuir probe is measuring the entire ion population (free and trapped ions), while the Cassini magnetometer detects the magnetic perturbations associated with pickup currents from the smaller population of free ions, with this distinction possibly reconciling the ongoing debate in the literature on the ion density in the plume.

  15. Plasma observations during the Mars atmospheric "plume" event of March-April 2012

    Science.gov (United States)

    Andrews, D. J.; Barabash, S.; Edberg, N. J. T.; Gurnett, D. A.; Hall, B. E. S.; Holmström, M.; Lester, M.; Morgan, D. D.; Opgenoorth, H. J.; Ramstad, R.; Sanchez-Cano, B.; Way, M.; Witasse, O.

    2016-04-01

    We present initial analyses and conclusions from plasma observations made during the reported "Mars plume event" of March-April 2012. During this period, multiple independent amateur observers detected a localized, high-altitude "plume" over the Martian dawn terminator, the cause of which remains to be explained. The estimated brightness of the plume exceeds that expected for auroral emissions, and its projected altitude greatly exceeds that at which clouds are expected to form. We report on in situ measurements of ionospheric plasma density and solar wind parameters throughout this interval made by Mars Express, obtained over the same surface region but at the opposing terminator. Measurements in the ionosphere at the corresponding location frequently show a disturbed structure, though this is not atypical for such regions with intense crustal magnetic fields. We tentatively conclude that the formation and/or transport of this plume to the altitudes where it was observed could be due in part to the result of a large interplanetary coronal mass ejection (ICME) encountering the Martian system. Interestingly, we note that the only similar plume detection in May 1997 may also have been associated with a large ICME impact at Mars.

  16. Instabilities of plumes driven by localized heating in a stably stratified ambient

    Science.gov (United States)

    Marques, Francisco; Lopez, Juan

    2014-11-01

    Plumes due to localized buoyancy sources are of wide interest due to their prevalence in many geophysical situations. This study investigates the transition from laminar to turbulent dynamics. Several experiments have reported that this transition is sensitive to external perturbations. As such, a well-controlled set-up has been chosen for our numerical study, consisting of a localized heat source at the bottom of an enclosed cylinder whose sidewall is maintained at a fixed temperature which varies linearly up the wall, and there is a localized heat source on the bottom. Restrincting the dynamics to the axisymmetric subspace, the first instability is to a puffing state. However, for smaller Grashof numbers, the plume becomes unstable to 3D perturbations and a swirling plume spontaneously appear. Further bifurcations observed in the rotating frame where the plume is stationary also exibits puffing, suggesting a connection between the unstable axisymmetric solution and the swirling plume. Further bifurcations result in quasiperiodic states with a very low frequency modulation, that eventually become turbulent. Spanish Ministry of Education and Science Grant (with FEDER funds) FIS2013-40880 and U.S. National Science Foundation Grant CBET-1336410

  17. Synthesizing Seismic Velocities of The Iceland Plume and Comparison With Observation

    Science.gov (United States)

    Schmeling, H.; Ruedas, T.; Marquart, G.

    Different seismological observations provide complementing views of the seismic anomalies beneath the Iceland Hotspot. While tomographic inversions seem to be able to identify the plume stem as a vertically elongated region of a few % shear wave velocity anomalies, surface wave inversions and receiver function methods sug- gest strong velocitiy decreases within the shallow parts of the plume. To explain such sets of observations 3D dynamical models of a plume rising beneath a spreading ridge have been carried out, including melt generation and extraction at certain critical melt porosities. The melt porosity and anomalous temperatures are used to determine syn- thetic seismic velocities, including anharmonic and anelastic effects for the temper- ature dependences. Relative to a reference profile of a normal oceanic lithosphere strong shear velocity reductions are predicted within the shallow partially molten re- gion beneath the ridge, while at greater depths (melt free plume stem) the effect of the excess plume temperature is only small. It is tested whether the velocity anomalies can be reconciled with the tomographic values, and what the consequences are for melt production rates.

  18. Microphysics and heterogeneous chemistry in aircraft plumes - high sensitivity on local meteorology and atmospheric composition

    Directory of Open Access Journals (Sweden)

    S. K. Meilinger

    2005-01-01

    Full Text Available An aircraft plume model has been developed on the basis of two coupled trajectory box models. Two boxes, one for plume and one for background conditions, are coupled by means of a mixing parameterization based on turbulence theory. The model considers comprehensive gas phase chemistry for the tropopause region including acetone, ethane and their oxidation products. Heterogeneous halogen, N2O5 and HOx chemistry on various types of background and aircraft-induced aerosols (liquid and ice is considered, using state-of-the-art solubility dependent uptake coefficients for liquid phase reactions. The microphysical scheme allows for coagulation, gas-diffusive particle growth and evaporation, so that the particle development from 1s after emission to several days can be simulated. Model results are shown, studying emissions into the upper troposphere as well as into the lowermost stratosphere for contrail and non-contrail conditions. We show the microphysical and chemical evolution of spreading plumes and use the concept of mean plume encounter time, tl, to define effective emission and perturbation indices (EEIs and EPIs for the North Atlantic Flight Corridor (NAFC showing EEI(NOy and EPI(O3 for various background conditions, such as relative humidity, local time of emission, and seasonal variations. Our results show a high sensitivity of EEI and EPIs on the exact conditions under which emissions take place. The difference of EEIs with and without considering plume processes indicates that these processes cannot be neglected.

  19. Lifting the lid on toilet plume aerosol: a literature review with suggestions for future research.

    Science.gov (United States)

    Johnson, David L; Mead, Kenneth R; Lynch, Robert A; Hirst, Deborah V L

    2013-03-01

    The potential risks associated with "toilet plume" aerosols produced by flush toilets is a subject of continuing study. This review examines the evidence regarding toilet plume bioaerosol generation and infectious disease transmission. The peer-reviewed scientific literature was searched to identify articles related to aerosol production during toilet flushing, as well as epidemiologic studies examining the potential role of toilets in infectious disease outbreaks. The studies demonstrate that potentially infectious aerosols may be produced in substantial quantities during flushing. Aerosolization can continue through multiple flushes to expose subsequent toilet users. Some of the aerosols desiccate to become droplet nuclei and remain adrift in the air currents. However, no studies have yet clearly demonstrated or refuted toilet plume-related disease transmission, and the significance of the risk remains largely uncharacterized. Research suggests that toilet plume could play a contributory role in the transmission of infectious diseases. Additional research in multiple areas is warranted to assess the risks posed by toilet plume, especially within health care facilities. Copyright © 2013 Association for Professionals in Infection Control and Epidemiology, Inc. All rights reserved.

  20. Radiatively-driven processes in forest fire and desert dust plumes

    Energy Technology Data Exchange (ETDEWEB)

    Weinzierl, Bernadett Barbara

    2008-07-01

    The absorption of solar radiation by atmospheric aerosol particles is important for the climate effects of aerosols. Absorption by aerosol particles heats atmospheric layers, even though the net effect for the entire atmospheric column may still be a cooling. Most experimental studies on absorbing aerosols so far focussed mainly on the aerosol properties and did not consider the influence of the aerosols on the thermodynamic structure of the atmosphere. In this study, data from two international aircraft field experiments, the Intercontinental Transport of Ozone and Precursors study (ITOP) 2004 and the Saharan Mineral Dust Experiment (SAMUM) 2006 are investigated. The ITOP data were collected before the work on this thesis started, while the logistics and the instrument preparation of the SAMUM campaign, the weather forecast during SAMUM and the in-situ aerosol measurements during SAMUM were done within this thesis. The experimental data are used to explore the impact of layers containing absorbing forest fire and desert dust aerosol particles on the atmospheric stability and the implications of a changed stability on the development of the aerosol microphysical and optical properties during long-range transport. For the first time, vertical profiles of the Richardson number Ri are used to assess the stability and mixing in forest fire and desert dust plumes. Also for the first time, the conclusions drawn from the observations of forest fire and desert dust aerosol, at first glance apparently quite different aerosol types, are discussed from a common perspective. Two mechanisms, the selfstabilising and the sealed ageing effect, acting in both forest fire and desert dust aerosol layers, are proposed to explain the characteristic temperature structure as well as the aerosol properties observed in lofted forest fire and desert dust plumes. The proposed effects impact on the ageing of particles within the plumes and reduce the plume dilution, therefore extending the

  1. Surface river plume in a large lake under wind forcing: Observations and laboratory experiments

    Science.gov (United States)

    Demchenko, Natalia; He, Cheng; Rao, Yerubandi R.; Valipour, Reza

    2017-10-01

    Observations of a small riverine plume (Grand River, ON) in the nearshore zones of Lake Erie were analyzed to describe its spatial variability and its thickness under different wind forcing conditions during late spring of 2012. Observational results reveal a well-marked frontal region in the vicinity of the river mouth, causing the plume to discharge into the lake in the surface layers (positive buoyant). Wind driven alongshore currents at the mid-depth had speeds of 2-9 cm/s, in comparison to those in the cross-shore 3-6 cm/s, which transported the plume along the shore during the measurement period. Series of laboratory experiments were conducted to obtain the propagation speed (U) of the buoyant plume in terms of buoyancy anomaly (Ba), Richardson number (Ri), dimensionless time (t‧), and aspect ratio (A). Based on our experiments, we developed two non-dimensional relationships describing the speed of propagation (U) as U/Ba1/2 = 8 Ri-1/2t‧1/3A and the plume thickness (h) as h/H = 0.8 Ri-1/4t‧1/2A in the water depth (H), which are in agreement with field observations.

  2. Observation of the volcanic plume of Eyjafjallajoekull over continental Europe by MAX-DOAS

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, S.; Bobrowski, N.; Friess, U.; Platt, U. [IUP, University of Heidelberg (Germany); Flentje, H. [DWD, Hohenpeissenberg (Germany); Hoermann, C.; Sihler, H. [IUP, University of Heidelberg (Germany); MPI, Mainz (Germany); Kern, C. [USGS, Vancouver (Canada); Wagner, T. [MPI, Mainz (Germany)

    2011-07-01

    The recent eruption of Eyjafjallajoekull Volcano (Iceland) and the emitted ash plume which disrupted commercial air traffic over Europe has led to an exhaustive debate on how to improve our ability to quantitatively determine the ash load in the atmosphere as a function of time and geographical location. Satellite instruments detecting ash and SO{sub 2} and ground-based LIDAR stations can help constrain atmospheric transport and meteorology models used to predict ash dispersion. However, MAX-DOAS represents an additional tool with considerable potential for the quantitative detection of elevated volcanic ash and SO{sub 2} plumes. It performs especially well during weather conditions in which satellites and LIDARs are impeded in their effectiveness, e.g. in the case of dense clouds above or below the plume, respectively. Here, the advantages and disadvantages of the DOAS technique are discussed, and its potential for monitoring of volcanic ash hazards explored. Results of ash and SO{sub 2} measurements of the Eyjafjallajoekull plume as it passed over Heidelberg are presented as an example of a positive detection of a highly diluted volcanic plume. Their low cost and complementary nature makes MAX-DOAS a promising technology in the field of aviation hazard detection and management.

  3. Particle Size Distributions Measured in the Stratospheric Plumes of Three Rockets During the ACCENT Missions

    Science.gov (United States)

    Wiedinmyer, C.; Brock, C. A.; Reeves, J. M.; Ross, M. N.; Schmid, O.; Toohey, D.; Wilson, J. C.

    2001-12-01

    The global impact of particles emitted by rocket engines on stratospheric ozone is not well understood, mainly due to the lack of comprehensive in situ measurements of the size distributions of these emitted particles. During the Atmospheric Chemistry of Combustion Emissions Near the Tropopause (ACCENT) missions in 1999, the NASA WB-57F aircraft carried the University of Denver N-MASS and FCAS instruments into the stratospheric plumes from three rockets. Size distributions of particles with diameters from 4 to approximately 2000 nm were calculated from the instrument measurements using numerical inversion techniques. The data have been averaged over 30-second intervals. The particle size distributions observed in all of the rocket plumes included a dominant mode near 60 nm diameter, probably composed of alumina particles. A smaller mode at approximately 25 nm, possibly composed of soot particles, was seen in only the plumes of rockets that used liquid oxygen and kerosene as a propellant. Aircraft exhaust emitted by the WB-57F was also sampled; the size distributions within these plumes are consistent with prior measurements in aircraft plumes. The size distributions for all rocket intercepts have been fitted to bimodal, lognormal distributions to provide input for global models of the stratosphere. Our data suggest that previous estimates of the solid rocket motor alumina size distributions may underestimate the alumina surface area emission index, and so underestimate the particle surface area available for heterogeneous chlorine activation reactions in the global stratosphere.

  4. Seasonal variability of Martian ion escape through the plume and tail from MAVEN observations

    Science.gov (United States)

    Dong, Y.; Fang, X.; Brain, D. A.; McFadden, J. P.; Halekas, J. S.; Connerney, J. E. P.; Eparvier, F.; Andersson, L.; Mitchell, D.; Jakosky, B. M.

    2017-04-01

    We study the Mars Atmosphere and Volatile Evolution spacecraft observations of Martian planetary ion escape during two time periods: 11 November 2014 to 19 March 2015 and 4 June 2015 to 24 October 2015, with the focus on understanding the seasonal variability of Martian ion escape in response to the solar extreme ultraviolet (EUV) flux. We organize the >6 eV O+ ion data by the upstream electric field direction to estimate the escape rates through the plume and tail. To investigate the ion escape dependence on the solar EUV flux, we constrain the solar wind dynamic pressure and interplanetary magnetic filed strength and compare the ion escape rates through the plume and tail in different energy ranges under high and low EUV conditions. We found that the total >6 eV O+ escape rate increases from 2 to 3 × 1024 s-1 as the EUV irradiance increases by almost the same factor, mostly on the <1 keV tailward escape. The plume escape rate does not vary significantly with EUV. The relative contribution from the plume to the total escape varies between 30% and 20% from low to high EUV. Our results suggest that the Martian ion escape is sensitive to the seasonal EUV variation, and the contribution from plume escape becomes more important under low EUV conditions.

  5. Nature of suspended particles in hydrothermal plume at 3°40'N Carlsberg ridge: A comparison with deep oceanic suspended matter

    Digital Repository Service at National Institute of Oceanography (India)

    Ray, D.; Babu, E.V.S.S.K.; SuryaPrakash, L.

    the plume. Concentration of particulate Mn is similar to that reported in Gorda Ridge plumes (0.76–1.66 nmol/l)3, but higher than Carlsberg event plume (0.46 nmol/l)9 or Rain- bow plume particulates (<0.5 nmol/l)4. Dissolved Mn in hydrothermal plume...-Sea Res. II, 1998, 45, 2637–2664. 4. Edmond, H. N. and German, C. R., Particle geochemistry of Rain- bow hydrothermal plume; Mid-Atlantic Ridge. Geochim. Cosmo- chim. Acta, 2004, 68, 759–772. 5. Lerche, D. and Nozaki, Y., Rare earth elements of sinking...

  6. Investigating near-glacier circulation and plume theory with high-resolution fjord surveys in West Greenland

    Science.gov (United States)

    Jackson, R. H.; Nash, J. D.; Shroyer, E.; Sutherland, D.; Fried, M.; Catania, G. A.; Carroll, D.; Bartholomaus, T. C.; Stearns, L. A.

    2016-12-01

    The plumes that emanate from Greenland's glaciers are hotspots of mixing between meltwater and ambient fjord waters. The dynamics of these plumes affect both submarine melting of glacier termini and the dilution of freshwater as it is exported into the ocean. Modeling studies often rely on buoyant plume theory to represent the circulation and mixing at the ocean/ice interface. However, a dearth of measurements in the near-glacier region has left open many questions about glacial plumes, entrainment, and the applicability of idealized plume theory to these environments. Here, we present near-glacier ocean surveys from Kangerdlugssuaq Sermerssua in central West Greenland in three consecutive summers (2013-2015). High-resolution measurements of velocity and water properties were collected by ship, by surface drifters, and by a remotely operated surface vessel - all focusing on the region within 2 km of the glacier terminus. These novel measurements of the 3D circulation capture a persistent near-surface plume, along with its time-evolution over a tidal cycle and between different summers. Concurrent multibeam sonar measurements of the submarine terminus morphology show that the plume emerges from a large undercut subglacial channel outlet. Plume theory, when applied with this fjord's stratification and any flux of subglacial discharge, cannot match the observed plume's volume flux and water properties. The discrepancy between our observations and plume theory suggests that there is enhanced entrainment at depth that is not adequately represented in plume theory. The details of this entrainment have important consequences for submarine melt rates, terminus morphology, and fjord circulation.

  7. Bubble plumes in a stratified environment: Source parameters, scaling, intrusion height, and neutral height

    Science.gov (United States)

    Chu, Shigan; Prosperetti, Andrea

    2017-10-01

    A cross-sectionally averaged model is used to study several aspects of the physics of a bubble plume rising in a stratified quiescent liquid. Scaling analyses for the peel height, at which the plume momentum vanishes, and the neutral height, at which its average density equals the ambient density, are presented. Contrary to a widespread practice in the literature, it is argued that the neutral height cannot be identified with the experimentally reported intrusion height. Recognizing this difference provides an explanation of the reason why the intrusion height is found so frequently to be much above predictions and brings the theoretical results in line with observations. The mathematical model depends on three dimensionless parameters, some of which are related to the inlet conditions at the plume source. Their influence on the peel and neutral heights is illustrated by means of physical considerations, scaling analyses, and numerical results.

  8. The role of sulfur emission in volatile particle formation in jet aircraft exhaust plumes

    Science.gov (United States)

    Kärcher, B.; Fahey, D. W.

    Recent in-situ emission measurements of the Concorde in the lower stratosphere point to a surprisingly efficient conversion of fuel sulfur to H2SO4 in the exhaust plume. By means of a comprehensive model, the formation and evolution of aerosol particles and precursors are calculated in the diluting aircraft wake. The results provide strong evidence that high levels of SO3 present in the nascent plume are required to explain the observations of large numbers of nanometer-sized aerosols. Limiting particle formation at emission to keep potential chemical effects on stratospheric ozone small will require control of the sulfur oxidation kinetics during fuel combustion. The similarities between super- and subsonic exhaust plumes suggest that the presence of SO3 in the latter will also be a key limiting factor in new aerosol production.

  9. Experimental study of window-ejected flame and plume on glass curtain walls

    Directory of Open Access Journals (Sweden)

    Peng Lei

    2016-01-01

    Full Text Available This research presents an experimental study to investigate the performance of glass curtain walls exposed to exterior flame and plume ejected from windows. A test facility with 3-storey in height was constructed using steel frame to perform full-scale tests. Ventilation-controlled fire scenarios were designed to generate exterior flame and plume ejected from the burning room through a window opening. To characterize potential threats from window-ejected flame and plume to the glass curtain walls of upper floors, temperature, heat flux and air velocity at different heights above the opening upon curtain walls were measured during each test. The effects of window aspect ratio, horizontal projection were studied. It was found that the window with large aspect ratio provided more severe threat to the curtain walls on upper floors. A horizontal projection of 0.5m in depth was able to protect the glass on the upper floor from breaking.

  10. Dynamics of the plume produced by nanosecond ultraviolet laser ablation of metals

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Schou, Jørgen; Lunney, J.G.

    2003-01-01

    The dynamics of the ablation plume of a partially ionized plasma produced by a nanosecond UV laser with different irradiation spot geometries has been explored. We have used an ensemble of quartz crystal microbalances to make the first systematic and quantitative study of how the shape of the plume...... varies as the aspect ratio (b/a) of the elliptical laser spot is varied by about a factor of ten. The flip-over effect can be described by the adiabatic expansion model of Anisimov using a value of the adiabatic constant of about gamma = 1.4. We have also studied the forward peaking of the ablation plume...... for a large number of metals at the same laser fluence. Contrary to earlier reports, we find that the more refractory metals have the broader angular distributions....

  11. In situ measurements of HO{sub x} in super- and subsonic aircraft exhaust plumes

    Energy Technology Data Exchange (ETDEWEB)

    Hanisco, T.F.; Wennberg, P.O.; Cohen, R.C.; Anderson, J.G. [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry; Fahey, D.W.; Keim, E.R.; Gao, R.S.; Wamsley, R.C.; Donnelly, S.G.; Del Negro, L.A. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Aeronomy Lab.; and others

    1997-12-31

    Concentrations of HO{sub x} (OH and HO{sub 2}) have been obtained in the exhaust plumes of an Air France Concorde and a NASA ER-2 in the lower stratosphere and the NASA DC-8 in the upper troposphere using instruments aboard the NASA ER-2. These fast-time response in situ measurements are used in conjunction with simultaneous in situ measurements of other key exhaust species (NO, NO{sub 2}, NO{sub y}, H{sub 2}O, and CO) to analyze the emissions of HO{sub x} from each aircraft under a variety of conditions. The data are used to establish a general description of gas phase plume chemistry that is easily implemented in a photochemical model. This model is used to determine the amount of HO{sub x} emitted from the engines and the gas phase oxidation rates of nitrogen and sulfur species in the exhaust plumes. (author) 10 refs.

  12. Pollution plumes observed during CARIBIC flights in the upper troposphere between South China and the Philippines

    Science.gov (United States)

    Lai, S. C.; Baker, A. K.; Schuck, T. J.; van Velthoven, P.; Oram, D. E.; Zahn, A.; Hermann, M.; Weigelt, A.; Slemr, F.; Brenninkmeijer, C. A. M.

    2009-10-01

    A strong pollution episode in the upper troposphere between South China and the Philippines was observed during CARIBIC flights in April 2007. Five pollution plumes were intersected and enhancements in aerosol and trace gas concentrations including CO, CO2, CH4, non-methane hydrocarbons (NMHCs) and halocarbons were observed along the flight tracks during four sequential flights. The importance of the contribution of biomass burning was investigated using chemical tracers, emission factor analysis, back-trajectory analysis and satellite images. The Indochinese peninsula was identified as the probable source region of biomass/biofuel burning. However, enhancements in the urban/industrial tracer C2Cl4 in the plumes also indicate a substantial contribution from anthropogenic emissions. An estimation of the anthropogenic component of CO shows that biomass/biofuel burning contributed 44-63% to the intersected plumes.

  13. Aerosol Optical Properties of Pacaya Volcano Plume Measured with a Portable Sun-Photometer

    Directory of Open Access Journals (Sweden)

    Pasquale Sellitto

    2018-01-01

    Full Text Available In this paper, Sun-photometer multichannel measurements of aerosol optical depths (AODs in the visible and near-infrared spectral ranges, and Ångström parameters of the plume issued from the Pacaya volcano, Guatemala, are presented for the first time. These observations, made during a short-term campaign carried out on 29 and 30 January 2011, indicate a diluted (AODs lower than 0.1 volcanic plume composed of small particles (Ångström exponent ∼1.0 on 29 January and ∼1.4 on 30 January. Results are consistent with an ash-free plume. Finally, the impact of the choice of different wavelength pairs for the calculation of the Ångström parameters from the spectral AOD observations is tested and critically discussed.

  14. Space Shuttle and Launch Pad Lift-Off Debris Transport Analysis: SRB Plume-Driven

    Science.gov (United States)

    West, Jeff; Strutzenberg, Louis; Dougherty, Sam; Radke, Jerry; Liever, Peter

    2007-01-01

    This paper discusses the Space Shuttle Lift-Off model developed for potential Lift-Off Debris transport. A critical Lift-Off portion of the flight is defined from approximately 1.5 sec after SRB Ignition up to 'Tower Clear', where exhaust plume interactions with the Launch Pad occur. A CFD model containing the Space Shuttle and Launch Pad geometry has been constructed and executed. The CFD model works in conjunction with a debris particle transport model and a debris particle impact damage tolerance model. These models have been used to assess the effects of the Space Shuttle plumes, the wind environment, their interactions with the Launch Pad, and their ultimate effect on potential debris during Lift-Off. Emphasis in this paper is on potential debris that might be caught by the SRB plumes.

  15. Plume characteristics and dynamics of UV and IR laser-desorbed oligonucleotides.

    Science.gov (United States)

    Merrigan, Tony L; Timson, David J; Hunniford, C Adam; Catney, Martin; McCullough, Robert W

    2012-05-01

    Laser desorption of dye-tagged oligonucleotides was studied using laser-induced fluorescence imaging. Desorption with ultra violet (UV) and infra-red (IR) lasers resulted in forward directed plumes of molecules. In the case of UV desorption, the initial shot desorbed approximately seven-fold more material than subsequent shots. In contrast, the initial shot in IR desorption resulted in the ejection of less material compared to subsequent shots and these plumes had a component directed along the path of the laser. Thermal equilibrium of the molecules in the plume was achieved after approximately 25 μs with a spread in molecular temperature which was described by a modified Maxwell-Boltzmann equation. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. 3D CFD simulations of trailing suction hopper dredger plume mixing: comparison with field measurements.

    Science.gov (United States)

    de Wit, Lynyrd; Talmon, A M; van Rhee, C

    2014-11-15

    A 3D computational fluid dynamics (CFD) model is used to simulate mixing of an overflow plume within 400 m from a trailing suction hopper dredger (TSHD). The simulations are compared with new field measurements. It is the first time simulations of overflow dredging plumes are compared in such detail to field measurements this close to a TSHD. Seven cases with a large variety in overflow flux and plume characteristics are used. Measured maximum suspended sediment concentrations (SSC) vary between 30 and 500 mg/l and fluxes vary between 0.7% and 20% of the total overflow flux; the CFD model has, subject to the limitations of the field data, been shown to reproduce this in a satisfactory way. The model gives better understanding of important near field processes, which helps to assess the frequency, duration and intensity of stresses like turbidity and sedimentation needed to find the environmental impact of dredging projects. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Influence of the atomic mass of the background gas on laser ablation plume propagation

    Science.gov (United States)

    Amoruso, Salvatore; Schou, Jørgen; Lunney, James G.

    2008-09-01

    A combination of time-of-flight ion probe measurements and gas dynamical modeling has been used to investigate the propagation of a laser ablation plume in gases of different atomic/molecular weight. The pressure variation of the ion time-of-flight was found to be well described by the gas dynamical model of Predtechensky and Mayorov (Appl. Supercond. 1:2011, 1993). In particular, the model describes how the pressure required to stop the plume in a given distance depends on the atomic/molecular weight of the gas, which is a feature that cannot be explained by standard point-blast-wave descriptions of laser ablation plume expansion in gas.

  18. Perturbation of the aerosol layer by aviation-produced aerosols: a parametrization of plume processes

    Energy Technology Data Exchange (ETDEWEB)

    Kaercher, B. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Wessling (Germany). Inst. fuer Physik der Atmosphaere; Meilinger, S. [Max-Planck-Institut fuer Chemie (Otto-Hahn-Institut), Mainz (Germany)

    1998-11-01

    The perturbation of the sulfate surface area density (SAD) in the tropopause region and the lower stratosphere by subsonic and supersonic aircraft fleets is examined. The background aerosol surface area, the conversion of fuel sulfur into new sulfate particles in aircraft plumes, and the plume mixing with ambient air control this perturbation. The background aerosol surface area is enhanced by the addition of ultrafine aerosol particles at cruise altitudes. The study includes recent findings concerning the formation and development of these particles in aircraft plumes. Large-scale SAD enhancements become relevant for background SAD levels below about 10 {mu}m{sup 2}/cm{sup 3}, even for moderate sulfate conversion fractions of 5%. Results from an analytic expression for the surface area changes are presented which contains the dependences on these parameters and can be employed in large-scale atmospheric models. (orig.) 11 refs.

  19. Shock wave mediated plume chemistry for molecular formation in laser ablation plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; Brumfield, Brian E.; Cannon, Bret D.; Phillips, Mark C.

    2016-02-16

    Laser ablation is used in a variety of applications albeit formation mechanisms of molecules and nanoclusters are not well understood. We investigated the formation mechanisms of AlO molecules during complex interactions between an Al laser plume expanding into ambient air at atmospheric pressure levels. To produce the plasma a high-purity Al target was ablated using 1064 nm, 6 ns laser pulses. Our results show that the plasma chemistry leading to the formation of AlO is mediated by shock waves. During the early times of plasma expansion, the generated shock waves at the plume edges act as a barrier for the combustion process and the molecular formation is prevalent after the shockwave collapse. The temporally and spatially resolved contour mapping of Al and AlO highlight the formation routes and persistence of species in the plasma and its relation to plume hydrodynamics.

  20. Inhomogeneous distribution of Chlamydomonas in a cylindrical container with a bubble plume

    Directory of Open Access Journals (Sweden)

    Yuki Nonaka

    2016-02-01

    Full Text Available Swimming microalgae show various taxes, such as phototaxis and gravitaxis, which sometimes result in the formation of a cell-rich layer or a patch in a suspension. Despite intensive studies on the effects of shear flow and turbulence on the inhomogeneous distribution of microalgae, the effect of a bubble plume has remained unclear. In this study, we used Chlamydomonas as model microalgae, and investigated the spatial distribution of cells in a cylindrical container with a bubble plume. The results illustrate that cells become inhomogeneously distributed in the suspension due to their motility and photo-responses. A vortical ring distribution was observed below the free surface when the bubble flow rate was sufficiently small. We performed a scaling analysis on the length scale of the vortical ring, which captured the main features of the experimental results. These findings are important in understanding transport phenomena in a microalgae suspension with a bubble plume.

  1. A Global Plume-Fed Europan Exosphere: Structure, Composition, Temporal Variability, and Surface Interactions

    Science.gov (United States)

    Teolis, B. D.; Waite, J. H., Jr.; Wyrick, D. Y.; Bouquet, A.; Magee, B.

    2014-12-01

    We present results from our Europa global exospheric modeling, which includes both sputtering / radiolytic and potential plume sources, and a sophisticated treatment of the exosphere-surface interaction, i.e., surface adsorption, regolith diffusion, polar cold trapping, and re-sputtering of adsorbed materials. We consider the effect of Europa's gravity in pulling plume vapor back to the surface and the subsequent spreading of adsorbed and exospheric material by thermal desorption and re-sputtering across the entire body. Our results show the global spatial distribution and temporal evolution of the surface exospheric density and composition for several scenarios, e.g., a solely sputtered / radiolytic exosphere, and the inclusion of transient and/or steady plume sources with an Enceladus-like composition. The model provides a useful tool for interpreting remote observations, and for extrapolating possible neutral and ion densities and compositional profiles along potential future spacecraft trajectories.

  2. Predictions of plume dispersion in complex terrain: Eulerian versus Lagrangian models

    Science.gov (United States)

    Nguyen, K. C.; Noonan, J. A.; Galbally, I. E.; Physick, W. L.

    Simulations of dispersion from an elevated point source in complex terrain and non-stationary flow are presented using the Lagrangian atmospheric dispersion model (LADM, Physick et al., 1992, Air Pollution Modeling and its Applications, Vol. IX, pp. 725-729, Plenum Press, New York; 1994 CSIRO Division of Atmospheric Research Technical Paper No. 24) and the Eulerian grid-based model (CALGRID, Yamartino et al., 1989, CALGRID: a mesoscale photochemical grid model, Vol. I; model formation document, Report, Sacarmento, California). Both models use the same predicted windfields. We find that • the different algorithms used for release of pollutants into the model domains lead to initial concentrations at the release height in LADM one-third higher than in CALGRID. • The CALGRID plume spreads laterally over a larger region than does the LADM plume due to the finite-difference approach of CALGRID. The pollutant mass in the extra volume occupied by the CALGRID plume is less than 10% of that released. • The essentials of morning fumigation are simulated more realistically under the Lagrangian approach. In LADM the elevated plume is mixed down to the ground rapidly, causing a sharp increase in ground-level concentrations (glc), whereas, in CALGRID glc increase more gradually over a few hours. • The use of hourly averaged windfields in CALGRID compared to 10 min windfields in LADM leads to a relative separation of the two modelled plumes of 5 km at a distance of roughly 6 km downwind from the sources at 1500 LST. Consequently in complex terrain and non-stationary conditions, the plumes are subjected to different three-dimensional wind regimes. For the particular terrain studied, roughly 3% of the pollutant mass emitted into CALGRID during the day is transported above 3000 m after 1700 LST whereas only 0.8% is transported above this height in LADM. • During the daytime the CALGRID simulation produces maximum glc which are about 40% smaller than those predicted by LADM.

  3. The onset of Walvis Ridge: Plume influence at the continental margin

    Science.gov (United States)

    Fromm, T.; Jokat, W.; Ryberg, T.; Behrmann, J. H.; Haberland, C.; Weber, M.

    2017-10-01

    The opening of the South Atlantic is a classical example for a plume related continental breakup. Flood basalts are present on both conjugate margins as well as aseismic ridges connecting them with the current plume location at Tristan da Cunha. To determine the effect of the proposed plume head on the continental crust, we acquired wide-angle seismic data at the junction of the Walvis Ridge with the African continent and modelled the P-wave velocity structure in a forward approach. The profile extends 430 km along the ridge and continues onshore to a length of 720 km. Crustal velocities beneath the Walvis Ridge vary between 5.5 km/s and 7.0 km/s, a typical range for oceanic crust. The crustal thickness of 22 km, however, is approximately three times larger than of normal oceanic crust. The continent-ocean transition is characterized by 30 km thick crust with strong lateral velocity variations in the upper crust and a high-velocity lower crust (HVLC), where velocities reach up to 7.5 km/s. The HVLC is 100 to 130 km wider at the Walvis Ridge than it is farther south, and impinges onto the continental crust of the Kaoko fold belt. Such high seismic velocities indicate Mg-rich igneous material intruded into the continental crust during the initial rifting stage. However, the remaining continental crust seems unaffected by intrusions and the root of the 40 km-thick crust of the Kaoko belt is not thermally abraded. We conclude that the plume head did not modify the continental crust on a large scale, but caused rather local effects. Thus, it seems unlikely that a plume drove or initiated the breakup process. We further propose that the plume already existed underneath the continent prior to the breakup, and ponded melt erupted at emerging rift structures providing the magma for continental flood basalts.

  4. Plume-based analysis of vehicle fleet air pollutant emissions and the contribution from high emitters

    Science.gov (United States)

    Wang, J. M.; Jeong, C.-H.; Zimmerman, N.; Healy, R. M.; Wang, D. K.; Ke, F.; Evans, G. J.

    2015-08-01

    An automated identification and integration method has been developed for in-use vehicle emissions under real-world conditions. This technique was applied to high-time-resolution air pollutant measurements of in-use vehicle emissions performed under real-world conditions at a near-road monitoring station in Toronto, Canada, during four seasons, through month-long campaigns in 2013-2014. Based on carbon dioxide measurements, over 100 000 vehicle-related plumes were automatically identified and fuel-based emission factors for nitrogen oxides; carbon monoxide; particle number; black carbon; benzene, toluene, ethylbenzene, and xylenes (BTEX); and methanol were determined for each plume. Thus the automated identification enabled the measurement of an unprecedented number of plumes and pollutants over an extended duration. Emission factors for volatile organic compounds were also measured roadside for the first time using a proton transfer reaction time-of-flight mass spectrometer; this instrument provided the time resolution required for the plume capture technique. Mean emission factors were characteristic of the light-duty gasoline-dominated vehicle fleet present at the measurement site, with mean black carbon and particle number emission factors of 35 mg kg fuel-1 and 7.5 × 1014 # kg fuel-1, respectively. The use of the plume-by-plume analysis enabled isolation of vehicle emissions, and the elucidation of co-emitted pollutants from similar vehicle types, variability of emissions across the fleet, and the relative contribution from heavy emitters. It was found that a small proportion of the fleet (carbon, carbon monoxide, BTEX, and particle number, respectively. Emission factors of a single pollutant may help classify a vehicle as a high emitter; however, regulatory strategies to more efficiently target multi-pollutant mixtures may be better developed by considering the co-emitted pollutants as well.

  5. Sensitivity analysis of the physical dynamics of the Fly River plume in Torres Strait

    Science.gov (United States)

    Li, Yanfang; Martins, Flavio; Wolanski, Eric

    2017-07-01

    The intrusion in the Torres Strait of the Fly River plume polluted by mine tailings is an international water issue. To investigate the physical mechanisms involved in the intrusion process, numerical simulations were conducted to assess the relative influence of the bathymetry and the external forcing, namely the tides, the mean sea level slope across the strait, river runoff and wind forcing. The wind data from Horn Island, the only long-term wind station in the Torres Strait, is shown to be unreliable due to orographic effects. Mean sea level data from altimetry compare well with those from tide gauges in these shallow, reef-studded waters. The wind has a dominant effect on the mean sea level at seasonal and inter-annual periods. The resulting mean sea level difference across the strait fluctuated seasonally and strongly influenced the intrusion of the Fly River plume in the Torres Strait. The 3D finite-volume MOHID model reproduced the observation that the river plume starts by being stratified in the Gulf of Papua where it originates, and it mixes vertically when it enters the Torres Strait. The MOHID and the SLIM models were applied with different resolution to the Torres Strait and responded similarly to the external forcings. The predicted and observed Fly River plume intrusion in the eastern Torres Strait agreed well with each other, including the formation of patches due to flow reversals. However, the two models predicted a widely different Fly River plume in its far field in the western Torres Strait, the differences were attributed to the different bathymetry in the Australian and British-US bathymetry data for these poorly charted waters, which demonstrated the importance of the details of the bathymetry in controlling the extent of plume intrusion.

  6. Non-Maxwellian electron energy probability functions in the plume of a SPT-100 Hall thruster

    Science.gov (United States)

    Giono, G.; Gudmundsson, J. T.; Ivchenko, N.; Mazouffre, S.; Dannenmayer, K.; Loubère, D.; Popelier, L.; Merino, M.; Olentšenko, G.

    2018-01-01

    We present measurements of the electron density, the effective electron temperature, the plasma potential, and the electron energy probability function (EEPF) in the plume of a 1.5 kW-class SPT-100 Hall thruster, derived from cylindrical Langmuir probe measurements. The measurements were taken on the plume axis at distances between 550 and 1550 mm from the thruster exit plane, and at different angles from the plume axis at 550 mm for three operating points of the thruster, characterized by different discharge voltages and mass flow rates. The bulk of the electron population can be approximated as a Maxwellian distribution, but the measured distributions were seen to decline faster at higher energy. The measured EEPFs were best modelled with a general EEPF with an exponent α between 1.2 and 1.5, and their axial and angular characteristics were studied for the different operating points of the thruster. As a result, the exponent α from the fitted distribution was seen to be almost constant as a function of the axial distance along the plume, as well as across the angles. However, the exponent α was seen to be affected by the mass flow rate, suggesting a possible relationship with the collision rate, especially close to the thruster exit. The ratio of the specific heats, the γ factor, between the measured plasma parameters was found to be lower than the adiabatic value of 5/3 for each of the thruster settings, indicating the existence of non-trivial kinetic heat fluxes in the near collisionless plume. These results are intended to be used as input and/or testing properties for plume expansion models in further work.

  7. Characterizing Offshore Earthquakes at Hawaii Recorded by the First PLUME Temporary Ocean-Bottom Seismometer Network

    Science.gov (United States)

    Anchieta, M. C.; Wolfe, C. J.; Laske, G.; Collins, J. A.; Solomon, S. C.; Detrick, R. S.; Orcutt, J. A.; Bercovici, D. A.; Hauri, E. H.; Pavlis, G. L.; Eakins, J. A.; Vernon, F. L.

    2007-12-01

    In 2005-2006 and again in 2006-2007, the Plume-Lithosphere Undersea Melt Experiment (PLUME) deployed successive networks of ocean-bottom seismometers (OBSs) around the Hawaiian Islands. The experiment consisted of a 2-year deployment of broadband land seismometers and two year-long deployments of broadband OBSs, the first with a station spacing of about 75 km centered on the island of Hawaii and the second with larger spacing of about 200 km. PLUME's major objective was to determine the mantle structure beneath the Hawaiian hotspot and swell; however, these unique data are also potentially valuable to the study of small offshore earthquakes. The Hawaiian Islands are marked by significant and continuous seismic activity. In addition to the thousands of microearthquakes that are detected and located by the USGS Hawaiian Volcano Observatory (HVO) seismic network each year, Hawaii also experiences occasional large, damaging earthquakes. Several of these large events occurred in Hawaii's offshore region (e.g., the 1871 Lanai earthquake, the 1938 Maui earthquake, and the 2006 Kiholo Bay earthquake), and such events pose a significant seismic hazard for the state. We assess whether data from the first PLUME OBS deployment and land data can improve the detection and location of offshore microearthquakes around Hawaii. We are particularly interested in whether the PLUME data set may reveal offshore fault zones not detected to date by the HVO seismic network. Initial tests indicate that many offshore earthquakes already in the HVO catalog produce detectable P and S waves on the PLUME three- component seismometers, and earthquake detection rates are improved when seismograms are high-pass filtered above about 5 Hz to reduce the seismic noise from wind-generated waves. Differential pressure gauge data yield far fewer detectable events (with the exception of a swarm of Loihi earthquakes in December 2005) and appear less promising for improving our knowledge of offshore

  8. A distribution-based parametrization for improved tomographic imaging of solute plumes

    Science.gov (United States)

    Pidlisecky, Adam; Singha, K.; Day-Lewis, F. D.

    2011-01-01

    Difference geophysical tomography (e.g. radar, resistivity and seismic) is used increasingly for imaging fluid flow and mass transport associated with natural and engineered hydrologic phenomena, including tracer experiments, in situ remediation and aquifer storage and recovery. Tomographic data are collected over time, inverted and differenced against a background image to produce 'snapshots' revealing changes to the system; these snapshots readily provide qualitative information on the location and morphology of plumes of injected tracer, remedial amendment or stored water. In principle, geometric moments (i.e. total mass, centres of mass, spread, etc.) calculated from difference tomograms can provide further quantitative insight into the rates of advection, dispersion and mass transfer; however, recent work has shown that moments calculated from tomograms are commonly biased, as they are strongly affected by the subjective choice of regularization criteria. Conventional approaches to regularization (Tikhonov) and parametrization (image pixels) result in tomograms which are subject to artefacts such as smearing or pixel estimates taking on the sign opposite to that expected for the plume under study. Here, we demonstrate a novel parametrization for imaging plumes associated with hydrologic phenomena. Capitalizing on the mathematical analogy between moment-based descriptors of plumes and the moment-based parameters of probability distributions, we design an inverse problem that (1) is overdetermined and computationally efficient because the image is described by only a few parameters, (2) produces tomograms consistent with expected plume behaviour (e.g. changes of one sign relative to the background image), (3) yields parameter estimates that are readily interpreted for plume morphology and offer direct insight into hydrologic processes and (4) requires comparatively few data to achieve reasonable model estimates. We demonstrate the approach in a series of

  9. Leachate plumes in ground water from Babylon and Islip landfills, Long Island, New York

    Science.gov (United States)

    Kimmel, Grant E.; Braids, O.C.

    1980-01-01

    Landfills operated by the towns of Babylon and Islip in southwest and central Suffolk County, N.Y., contain urban refuse incinerated garbage, and scavenger (cesspool) waste; some industrial refuse is deposited at the Babylon site. The Islip landfill was started in 1933, the Babylon landfill in 1947. The landfills are in contact with and discharge leachate into the highly permeable upper glacial aquifer (hydraulic conductivity 190 and 500 ft/d). The aquifer is 74 feet thick at the Babylon landfill and 170 feet thick at the Islip landfill. The leachate-enriched water occupies the boundaries retard downward migration of the plumes to deeper aquifers. The Babylon plume is 1,900 feet wide at the landfill and narrows to about 700 feet near its terminus 10,000 feet from the landfill. The Islip plume is 5,000 feet from the landfill. Hydrochemical maps and sections show the distribution of the major chemical constituents of the plumes. The most highly leachate-enriched ground water obtained was from the Babylon site; it contained 860 mg/L sodium, 110 mg/L potassium, 565 mg/L calcium, 100 mg/L magnesium, 2,7000 mg/L bicarbonate, and 1,300 mg/L chloride. Simulation of the movement and dispersion of the Babylon plume with a mathematical dispersion model indicated the coefficient of the longitudinal dispersion to be about 60 feet squared per day and the ground-water velocity to be 1 ft/d. However, the velocity determined from the hydraulic gradient and public-supply wells in the area was 4 ft/d, which would cause a plume four times as long as that predicted by the model. (Kosco-USGS)

  10. Interaction of Saturn's magnetosphere and its moons: 2. Shape of the Enceladus plume

    Science.gov (United States)

    Jia, Y.-D.; Russell, C. T.; Khurana, K. K.; Ma, Y. J.; Najib, D.; Gombosi, T. I.

    2010-04-01

    The Saturnian moons in the inner magnetosphere are immersed in a plasma disk that rotates much faster than the moon's Keplerian speed. The interaction of the rotating plasma with the moons results in a disturbance in the Saturnian magnetospheric plasma that depends on the nature of obstacle that the moon represents. In particular at Enceladus, such perturbations in the magnetic field and flowing plasma enable us to infer the 3-D shape of the Enceladus plume and its outgassing rate. In this paper, we apply our 3-D magnetohydrodynamic model to extensively study the effects of different plume and disk plasma conditions on the interaction. By finding the best agreement with the observations of two diagnostic flybys, one with its point of closest approach on the upstream side and the other on the downstream side, we determine the plume intensity and configuration. We find that mass loading in the plume is less efficient close to the surface of the moon, where the neutral density is the highest. For E2 and E5, the opening angle of the plume is about 20°, and the plume is tilted toward the corotating direction. The upstream density has a significant effect on the mass loading rate, while its effect on the magnitude of the magnetic perturbation is less significant. An upstream velocity component in the Saturn direction helps to explain the observed magnetic perturbation in the By component and signals the need to consider Enceladus's effect on the global plasma circulation in addition to the local effect. Quantitative comparisons of the simulated and observed interaction are provided.

  11. Partial nitrification enhances natural attenuation of nitrogen in a septic system plume.

    Science.gov (United States)

    Caschetto, M; Robertson, W; Petitta, M; Aravena, R

    2018-01-03

    Natural attenuation of nitrogen (N) was investigated in a well characterized septic system plume at a campground in Ontario, Canada. Total inorganic N (TIN) concentrations in deeper portions of the plume were about one third of the septic tank value of 40.7mgL-1. NH4+ and NO3- isotopic characterization were used to provide insight into potential attenuation processes. Concentrations of NH4+ and NO3- were highly variable in the plume, but approached the septic tank TIN value in some shallow zones and exhibited δ15N values like the tank value of +6‰. However, isotopic enrichment (up to +24‰ for NH4+ and +45‰ for NO3-) and declining TIN concentrations in the deeper zones indicated that anaerobic ammonium oxidation contributed to the TIN attenuation. The degree of isotopic enrichment increased at lower NH4+ concentrations and was consistent with Rayleigh-type distillation with an enrichment factor (Ɛ) of -5.1‰. Additionally, decreasing DOC values with depth and the concomitant enrichment of δ15NNO3 and δ18ONO3, suggested that denitrification was also active. The N attenuation observed in the Killarney plume was partly due to incomplete nitrification that occurred because of the shallow water table, which varied from only 0.2-0.7m below the tile bed infiltration pipes. Moreover, some of the monitoring locations with the shallowest water table distances from the infiltration pipes, had the highest degree of TIN attenuation (70-90%) in the plume. This behavior suggests that controlling water table distance from the infiltration pipes could be a useful mechanism for enhancing N attenuation in septic system plumes. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Mapping Pollution Plumes in Areas Impacted by Hurricane Katrina With Imaging Spectroscopy

    Science.gov (United States)

    Swayze, G. A.; Furlong, E. T.; Livo, K. E.

    2007-12-01

    New Orleans endured flooding on a massive scale subsequent to Hurricane Katrina in August of 2005. Contaminant plumes were noticeable in satellite images of the city in the days following flooding. Many of these plumes were caused by oil, gasoline, and diesel that leaked from inundated vehicles, gas stations, and refineries. News reports also suggested that the flood waters were contaminated with sewage from breached pipes. Effluent plumes such as these pose a potential health hazard to humans and wildlife in the aftermath of hurricanes and potentially from other catastrophic events (e.g., earthquakes, shipping accidents, chemical spills, and terrorist attacks). While the extent of effluent plumes can be gauged with synthetic aperture radar and broad- band visible-infrared images (Rykhus, 2005) (e.g., Radarsat and Landsat ETM+) the composition of the plumes could not be determined. These instruments lack the spectral resolution necessary to do chemical identification. Imaging spectroscopy may help solve this problem. Over 60 flight lines of NASA Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were collected over New Orleans, the Mississippi Delta, and the Gulf Coast from one to two weeks after Katrina while the contaminated water was being pumped out of flooded areas. These data provide a unique opportunity to test if imaging spectrometer data can be used to identify the chemistry of these flood-related plumes. Many chemicals have unique spectral signatures in the ultraviolet to near-infrared range (0.2 - 2.5 microns) that can be used as fingerprints for their identification. We are particularly interested in detecting thin films of oil, gasoline, diesel, and raw sewage suspended on or in water. If these materials can be successfully differentiated in the lab then we will use spectral-shape matching algorithms to look for their spectral signatures in the AVIRIS data collected over New Orleans and other areas impacted by Katrina. If imaging spectroscopy

  13. The role of HO_x in super- and subsonic aircraft exhaust plumes

    OpenAIRE

    Hanisco, T. F.; Wennberg, P. O.; R. C. Cohen; J. G. Anderson; D. W. Fahey; Keim, E. R; Gao, R. S.; Wamsley, R. C.; Donnelly, S. G.; Del Negro, L. A.; R. J. Salawitch; Kelly, K. K.; Proffitt, M.H.

    1997-01-01

    The generation of sulfuric acid aerosols in aircraft exhaust has emerged as a critical issue in determining the impact of supersonic aircraft on stratospheric ozone. It has long been held that the first step in the mechanism of aerosol formation is the oxidation of SO_(2) emitted from the engine by OH in the exhaust plume. We report in situ measurements of OH and HO_(2) in the exhaust plumes of a supersonic (Air France Concorde) and a subsonic (NASA ER-2) aircraft in the lower stratosphere. T...

  14. Episodic entrainment of primordial material in plumes from isolated lower mantle reservoirs

    Science.gov (United States)

    Williams, C. D.; McNamara, A. K.; Garnero, E. J.; Van Soest, M. C.

    2012-12-01

    The noble gas systematics observed in ocean island basalts (OIBs) relative to mid-ocean ridge basalts (MORBs), suggests OIBs preferentially sample a primordial reservoir located somewhere within Earth's mantle. The lower mantle has been favored as a candidate reservoir, either in its entirety or discrete reservoirs located within it. Thermal plumes originating from the lower mantle could potentially sample these reservoirs, which may have remained isolated from the MORB source region over much of Earth's history. Recently, seismic observations of two, nearly anti-podal large, low-shear velocity provinces (LLSVPs) in the lowermost mantle have been hypothesized as being chemically distinct, and thus, may be long-lived reservoirs that have retained primordial noble gas signatures from earlier in Earth's history. Geodynamic models predict that thermal plumes are likely to be associated with LLSVPs and could potentially entrain a small amount of these chemically distinct reservoirs, which may ultimately reach the surface of the Earth in the form of OIBs. However, isotopic variability within OIBs challenges the notion of multiple plumes tapping the same reservoir. Here, we perform geodynamic calculations that investigate the time-dependent rate of material entrained into thermal plumes from these primordial reservoirs. In particular, we examine how the rate of entrainment varies within a single, long-lived thermal plume with a relatively steady buoyancy flux. Using phase relations for mantle peridotite, the amount of entrained material comprising the melt is estimated. We find that time-dependent dynamical processes at the interface between a deep, primordial reservoir and the base of a mantle plume strongly influences the entrainment rate, causing the amount of entrainment to vary episodically with time. Thus, melts rising to the surface (e.g., OIBs) are predicted to contain variable proportions of material entrained from these primordial reservoirs. This time

  15. DSMC simulations of the Shuttle Plume Impingement Flight EXperiment(SPIFEX)

    Science.gov (United States)

    Stewart, Benedicte; Lumpkin, Forrest

    2017-01-01

    During orbital maneuvers and proximity operations, a spacecraft fires its thrusters inducing plume impingement loads, heating and contamination to itself and to any other nearby spacecraft. These thruster firings are generally modeled using a combination of Computational Fluid Dynamics (CFD) and DSMC simulations. The Shuttle Plume Impingement Flight EXperiment(SPIFEX) produced data that can be compared to a high fidelity simulation. Due to the size of the Shuttle thrusters this problem was too resource intensive to be solved with DSMC when the experiment flew in 1994.

  16. Development of procedures for the identification of human papilloma virus DNA fragments in laser plume

    Science.gov (United States)

    Woellmer, Wolfgang; Meder, Tom; Jappe, Uta; Gross, Gerd; Riethdorf, Sabine; Riethdorf, Lutz; Kuhler-Obbarius, Christina; Loening, Thomas

    1996-01-01

    For the investigation of laser plume for the existence of HPV DNA fragments, which possibly occur during laser treatment of virus infected tissue, human papillomas and condylomas were treated in vitro with the CO2-laser. For the sampling of the laser plume a new method for the trapping of the material was developed by use of water-soluble gelatine filters. These samples were analyzed with the polymerase chain reaction (PCR) technique, which was optimized in regard of the gelatine filters and the specific primers. Positive PCR results for HPV DNA fragments up to the size of a complete oncogene were obtained and are discussed regarding infectiousity.

  17. The Biogeochemistry of Contaminant Groundwater Plumes Arising from Waste Disposal Facilities

    DEFF Research Database (Denmark)

    Bjerg, Poul Løgstrup; Albrechtsen, Hans-Jørgen; Kjeldsen, Peter

    2014-01-01

    Landfills with solid waste are abundant sources of groundwater pollution all over the world. Old uncontrolled municipal landfills are often large, heterogeneous sources with demolition waste, minor fractions of commercial or industrial waste, and organic waste from households. Strongly anaerobic ...... at landfill sites. Finally, the potential chemical or ecological impact from landfills located in former wetlands or near surface water bodies may deserve attention in future studies....... and the heterogeneity of the source may create a variable leaching pattern and maybe also multiple plumes; and (4) significant natural attenuation of xenobiotic organic compounds occurs, but the complexity of leachate plumes with respect to compounds (inorganic and xenobiotic organic compounds) and biogeochemical...

  18. Fate of organic contaminants in the redox zones of a landfill leachate pollution plume (Vejen, Denmark)

    DEFF Research Database (Denmark)

    Lyngkilde, John; Christensen, Thomas Højlund

    1992-01-01

    Samples from 75 sample locations in a landfill leachate pollution plume reveal a significant disappearance of specific organic compounds (SOC's) within the first 100 m of the plume. Only the herbicide Mecoprop® (MCPP) migrates further. Since sorption and dilution cannot account for the decreasing...... by a significant ferrogenic zone exhibiting a substantial capacity to degrade the SOC's. The presence of intermediary products (here an oxidized camphor compound) supports the concept of degradation within the ferrogenic zone. This investigation draws the attention to the significant natural attenuation of organic...

  19. High-Resolution Spectroscopy of Laser Ablation Plumes Using Laser-Induced Fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; LaHaye, Nicole L.; Phillips, Mark C.

    2017-02-06

    We used a CW laser as a narrow-band (~50kHz) tunable LIF excitation source to probe absorption from selected atomic transitions (Al, U etc. ) in a ns laser ablation plume. A comparison of fluorescence signal with respect to emission spectroscopy show significant increase in the magnitude and persistence from selected Al and U transitions in a LIBS plume. The high spectral resolution provided by the LIF measurement allows peaks to be easily separated even if they overlap in the emission spectra.

  20. Two-dimensional fluorescence spectroscopy of uranium isotopes in femtosecond laser ablation plumes.

    Science.gov (United States)

    Phillips, Mark C; Brumfield, Brian E; LaHaye, Nicole; Harilal, Sivanandan S; Hartig, Kyle C; Jovanovic, Igor

    2017-