Science.gov

Sample records for 3-d general circulation

  1. 3D Simulations of the Early Mars Climate with a General Circulation Model

    NASA Technical Reports Server (NTRS)

    Forget, F.; Haberle, R. M.; Montmessin, F.; Cha, S.; Marcq, E.; Schaeffer, J.; Wanherdrick, Y.

    2003-01-01

    The environmental conditions that existed on Mars during the Noachian period are subject to debate in the community. In any case, there are compelling evidence that these conditions were different than what they became later in the amazonian and possibly the Hesperian periods. Indeed, most of the old cratered terrains are disected by valley networks (thought to have been carved by flowing liquid water), whereas younger surface are almost devoid of such valleys. In addition, there are evidence that the erosion rate was much higher during the early noachian than later. Flowing water is surprising on early Mars because the solar luminosity was significantly lower than today. Even with the thick atmosphere (up to several bars).To improve our understanding of the early Mars Climate, we have developed a 3D general circulation model similar to the one used on current Earth or Mars to study the details of the climate today. Our first objective is to answer the following questions : how is the Martian climate modified if 1) the surface pressure is increased up to several bars (our baseline: 2 bars) and 2) if the sun luminosity is decreased by 25 account the heat possibly released by impacts during short periods, although it may have played a role .For this purpose, we have coupled the Martian General Circulation model developed at LMD with a sophisticated correlated k distribution model developped at NASA Ames Research Center. It is a narrow band model which computes the radiative transfer at both solar and thermal wavelengths (from 0.3 to 250 microns).

  2. Comparing a quasi-3D to a full 3D nearshore circulation model: SHORECIRC and ROMS

    USGS Publications Warehouse

    Haas, K.A.; Warner, J.C.

    2009-01-01

    Predictions of nearshore and surf zone processes are important for determining coastal circulation, impacts of storms, navigation, and recreational safety. Numerical modeling of these systems facilitates advancements in our understanding of coastal changes and can provide predictive capabilities for resource managers. There exists many nearshore coastal circulation models, however they are mostly limited or typically only applied as depth integrated models. SHORECIRC is an established surf zone circulation model that is quasi-3D to allow the effect of the variability in the vertical structure of the currents while maintaining the computational advantage of a 2DH model. Here we compare SHORECIRC to ROMS, a fully 3D ocean circulation model which now includes a three dimensional formulation for the wave-driven flows. We compare the models with three different test applications for: (i) spectral waves approaching a plane beach with an oblique angle of incidence; (ii) monochromatic waves driving longshore currents in a laboratory basin; and (iii) monochromatic waves on a barred beach with rip channels in a laboratory basin. Results identify that the models are very similar for the depth integrated flows and qualitatively consistent for the vertically varying components. The differences are primarily the result of the vertically varying radiation stress utilized by ROMS and the utilization of long wave theory for the radiation stress formulation in vertical varying momentum balance by SHORECIRC. The quasi-3D model is faster, however the applicability of the fully 3D model allows it to extend over a broader range of processes, temporal, and spatial scales. ?? 2008 Elsevier Ltd.

  3. Quasi-horizontal circulation cells in 3D seawater intrusion

    USGS Publications Warehouse

    Abarca, E.; Carrera, J.; Sanchez-Vila, X.; Voss, C.I.

    2007-01-01

    The seawater intrusion process is characterized by the difference in freshwater and seawater density that causes freshwater to float on seawater. Many confined aquifers have a large horizontal extension with respect to thickness. In these cases, while buoyancy acts in the vertical direction, flow is confined between the upper and bottom boundaries and the effect of gravity is controlled by variations of aquifer elevation. Therefore, the effective gravity is controlled by the slope and the shape of the aquifer boundaries. Variability in the topography of the aquifer boundaries is one case where 3D analysis is necessary. In this work, density-dependent flow processes caused by 3D aquifer geometry are studied numerically and specifically, considering a lateral slope of the aquifer boundaries. Sub-horizontal circulation cells are formed in the saltwater entering the aquifer. The penetration of the saltwater can be quantified by a dimensionless buoyancy number that measures the lateral slope of the aquifer relative to freshwater flux. The penetration of the seawater intrusion wedge is controlled more by this slope than by the aquifer thickness and dispersivity. Thus, the slope must be taken into account in order to accurately evaluate seawater intrusion. ?? 2007 Elsevier B.V. All rights reserved.

  4. 3D Atmospheric Circulation of Warm and Hot Jupiters

    NASA Astrophysics Data System (ADS)

    Showman, Adam P.; Lewis, Nikole K.; Fortney, Jonathan J.

    2015-03-01

    Efforts to characterize extrasolar giant planet (EGP) atmospheres have so far emphasized planets within 0.05 AU of their stars. Despite this focus, known EGPs populate a continuum of orbital separations from canonical hot Jupiter values (0.03-0.05 AU) out to 1 AU and beyond. Unlike typical hot Jupiters, these more distant EGPs will not generally be synchronously rotating. In anticipation of observations of this population, we here present three-dimensional atmospheric circulation models exploring the dynamics that emerge over a broad range of rotation rates and incident stellar fluxes appropriate for warm and hot Jupiters. We find that the circulation resides in one of two basic regimes. On typical hot Jupiters, the strong day-night heating contrast leads to a broad, fast superrotating (eastward) equatorial jet and large day-night temperature differences. At faster rotation rates and lower incident fluxes, however, the day-night heating gradient becomes less important, and baroclinic instabilities emerge as a dominant player, leading to eastward jets in the midlatitudes, minimal temperature variations in longitude, and, often, weak winds at the equator. Our most rapidly rotating and least irradiated models exhibit similarities to Jupiter and Saturn, illuminating the dynamical continuum between hot Jupiters and the weakly irradiated giant planets of our own solar system. We present infrared (IR) light curves and spectra of these models, which depend significantly on incident flux and rotation rate. This provides a way to identify the regime transition in future observations. In some cases, IR light curves can provide constraints on the rotation rate of nonsynchronously rotating planets.

  5. Ocean General Circulation Models

    SciTech Connect

    Yoon, Jin-Ho; Ma, Po-Lun

    2012-09-30

    1. Definition of Subject The purpose of this text is to provide an introduction to aspects of oceanic general circulation models (OGCMs), an important component of Climate System or Earth System Model (ESM). The role of the ocean in ESMs is described in Chapter XX (EDITOR: PLEASE FIND THE COUPLED CLIMATE or EARTH SYSTEM MODELING CHAPTERS). The emerging need for understanding the Earth’s climate system and especially projecting its future evolution has encouraged scientists to explore the dynamical, physical, and biogeochemical processes in the ocean. Understanding the role of these processes in the climate system is an interesting and challenging scientific subject. For example, a research question how much extra heat or CO2 generated by anthropogenic activities can be stored in the deep ocean is not only scientifically interesting but also important in projecting future climate of the earth. Thus, OGCMs have been developed and applied to investigate the various oceanic processes and their role in the climate system.

  6. 3D movies for teaching seafloor bathymetry, plate tectonics, and ocean circulation in large undergraduate classes

    NASA Astrophysics Data System (ADS)

    Peterson, C. D.; Lisiecki, L. E.; Gebbie, G.; Hamann, B.; Kellogg, L. H.; Kreylos, O.; Kronenberger, M.; Spero, H. J.; Streletz, G. J.; Weber, C.

    2015-12-01

    Geologic problems and datasets are often 3D or 4D in nature, yet projected onto a 2D surface such as a piece of paper or a projection screen. Reducing the dimensionality of data forces the reader to "fill in" that collapsed dimension in their minds, creating a cognitive challenge for the reader, especially new learners. Scientists and students can visualize and manipulate 3D datasets using the virtual reality software developed for the immersive, real-time interactive 3D environment at the KeckCAVES at UC Davis. The 3DVisualizer software (Billen et al., 2008) can also operate on a desktop machine to produce interactive 3D maps of earthquake epicenter locations and 3D bathymetric maps of the seafloor. With 3D projections of seafloor bathymetry and ocean circulation proxy datasets in a virtual reality environment, we can create visualizations of carbon isotope (δ13C) records for academic research and to aid in demonstrating thermohaline circulation in the classroom. Additionally, 3D visualization of seafloor bathymetry allows students to see features of seafloor most people cannot observe first-hand. To enhance lessons on mid-ocean ridges and ocean basin genesis, we have created movies of seafloor bathymetry for a large-enrollment undergraduate-level class, Introduction to Oceanography. In the past four quarters, students have enjoyed watching 3D movies, and in the fall quarter (2015), we will assess how well 3D movies enhance learning. The class will be split into two groups, one who learns about the Mid-Atlantic Ridge from diagrams and lecture, and the other who learns with a supplemental 3D visualization. Both groups will be asked "what does the seafloor look like?" before and after the Mid-Atlantic Ridge lesson. Then the whole class will watch the 3D movie and respond to an additional question, "did the 3D visualization enhance your understanding of the Mid-Atlantic Ridge?" with the opportunity to further elaborate on the effectiveness of the visualization.

  7. 3D microfilter device for viable circulating tumor cell (CTC) enrichment from blood.

    PubMed

    Zheng, Siyang; Lin, Henry K; Lu, Bo; Williams, Anthony; Datar, Ram; Cote, Richard J; Tai, Yu-Chong

    2011-02-01

    Detection of circulating tumor cells has emerged as a promising minimally invasive diagnostic and prognostic tool for patients with metastatic cancers. We report a novel three dimensional microfilter device that can enrich viable circulating tumor cells from blood. This device consists of two layers of parylene membrane with pores and gap precisely defined with photolithography. The positions of the pores are shifted between the top and bottom membranes. The bottom membrane supports captured cells and minimize the stress concentration on cell membrane and sustain cell viability during filtration. Viable cell capture on device was investigated with scanning electron microscopy, confocal microscopy, and immunofluorescent staining using model systems of cultured tumor cells spiked in blood or saline. The paper presents and validates this new 3D microfiltration concept for circulation tumor cell enrichment application. The device provides a highly valuable tool for assessing and characterizing viable enriched circulating tumor cells in both research and clinical settings.

  8. Middle atmosphere general circulation statistics

    NASA Technical Reports Server (NTRS)

    Geller, M. A.

    1985-01-01

    With the increased availability of remote sensing data for the middle atmosphere from satellites, more analyses of the middle atmosphere circulation are being published. Some of these are process studies for limited periods, and some are statistical analyses of middle atmosphere general circulation statistics. Results from the latter class of studies will be reviewed. These include analysis of the zonally averaged middle atmosphere structure, temperature, and zonal winds; analysis of planetary wave structures, analysis of heat and momentum fluxes; and analysis of Eliassen-and-Palm flux vectors and flux divergences. Emphasis is on the annual march of these quantities; Northern and Southern Hemisphere asymmetries; and interannual variability in these statistics. Statistics involving the global ozone distribution and transports of ozone are also discussed.

  9. 3-D General Relativistic MHD Simulations of Generating Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Frank, J.; Sol, H.

    1999-05-01

    Koide et al have investigated the dynamics of an accretion disk initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state or in hydrostatic equilibrium) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code on a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics. 3-D RMHD simulations wil be also performed to investigate the dynamics of a jet with a helical mangetic field in it.

  10. Influence of the Aral Sea negative water balance on its seasonal circulation patterns: use of a 3D hydrodynamic model

    NASA Astrophysics Data System (ADS)

    Sirjacobs, D.; Grégoire, M.; Delhez, E.; Nihoul, J. C. J.

    2004-06-01

    A 3D hydrodynamic model of the Aral Sea was successfully implemented to address the complex hydrodynamic changes induced by the combined effect of hydrologic and climatic change in the Aral region. The first barotropic numerical experiments allowed us to produce a comparative description of the mean general seasonal circulation patterns corresponding to the original situation (1956-1960) and of the average situation for the period from 1981 to 1985, a very low river flow period. The dominant anticyclonic circulation suggested by our seasonal simulation is in good agreement with previous investigations. In addition, this main anticyclonic gyre was shown to be stable and clearly established from February to September, while winter winds led to another circulation scenario. In winter, the main anticyclonic gyre was considerably limited, and cyclonic circulations appeared in the deep western basin and in the northeast of the shallow basin. In contrast, stronger anticyclonic circulation was observed in the Small Aral Sea during winter. As a consequence of the 10-m sea level drop observed between the two periods considered, the 1981-1985 simulation suggests an intensification of seasonal variability. Total water transport of the main gyre was reduced with sea level drop by a minimum of 30% in May and up to 54% in September. Before 1960, the study of the net flows through Berg and Kokaral Straits allowed us to evaluate the component of water exchange between the Small and the Large Seas linked with the general anticyclonic circulation around Kokaral Island. This exchange was lowest in summer (with a mean anticyclonic exchange of 222 m 3/s for July and August), highest in fall and winter (with a mean value of 1356 m 3/s from September to February) and briefly reversed in the spring (mean cyclonic circulation of 316 m 3/s for April and May). In summer, the water exchange due to local circulation at the scale of each strait was comparatively more important because net flows

  11. 3-D General Relativistic MHD Simulations of Generating Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Frank, J.; Sol, H.

    1999-12-01

    We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state or in hydrostatic equilibrium) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics and jet generation.

  12. 3-D General Relativistic MHD Simulations of Generating Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.

    2001-12-01

    We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.

  13. 3-D General Relativistic MHD Simulations of Generating Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.

    2000-12-01

    We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics and jet generation.

  14. Jet Formation with 3-D General Relativistic MHD Simulations

    NASA Astrophysics Data System (ADS)

    Richardson, G. A.; Nishikawa, K.-I.; Preece, R.; Hardee, P.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.; Fishman, J.

    2002-12-01

    We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (in a steady-state infalling state) around a non-rotating black hole using 3-D GRMHD with the ``axisymmetry'' along the z-direction. The magnetic field is tightly twisted by the rotation of the accretion disk, and plasmas in the shocked region of the disk are accelerated by the J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and the magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.

  15. 3-D General Relativistic MHD Simulations of Generating Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, Ken-Ichi; Koide, Shinji; Shibata, Kazunari; Kudoh, Takashiro; Sol, Helene; Hughes, John

    2002-04-01

    We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J × B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.

  16. Robust Reconstruction and Generalized Dual Hahn Moments Invariants Extraction for 3D Images

    NASA Astrophysics Data System (ADS)

    Mesbah, Abderrahim; Zouhri, Amal; El Mallahi, Mostafa; Zenkouar, Khalid; Qjidaa, Hassan

    2017-03-01

    In this paper, we introduce a new set of 3D weighed dual Hahn moments which are orthogonal on a non-uniform lattice and their polynomials are numerically stable to scale, consequent, producing a set of weighted orthonormal polynomials. The dual Hahn is the general case of Tchebichef and Krawtchouk, and the orthogonality of dual Hahn moments eliminates the numerical approximations. The computational aspects and symmetry property of 3D weighed dual Hahn moments are discussed in details. To solve their inability to invariability of large 3D images, which cause to overflow issues, a generalized version of these moments noted 3D generalized weighed dual Hahn moment invariants are presented where whose as linear combination of regular geometric moments. For 3D pattern recognition, a generalized expression of 3D weighted dual Hahn moment invariants, under translation, scaling and rotation transformations, have been proposed where a new set of 3D-GWDHMIs have been provided. In experimental studies, the local and global capability of free and noisy 3D image reconstruction of the 3D-WDHMs has been compared with other orthogonal moments such as 3D Tchebichef and 3D Krawtchouk moments using Princeton Shape Benchmark database. On pattern recognition using the 3D-GWDHMIs like 3D object descriptors, the experimental results confirm that the proposed algorithm is more robust than other orthogonal moments for pattern classification of 3D images with and without noise.

  17. A 3D, finite element model for baroclinic circulation on the Vancouver Island continental shelf

    USGS Publications Warehouse

    Walters, R.A.; Foreman, M.G.G.

    1992-01-01

    This paper describes the development and application of a 3-dimensional model of the barotropic and baroclinic circulation on the continental shelf west of Vancouver Island, Canada. A previous study with a 2D barotropic model and field data revealed that several tidal constituents have a significant baroclinic component (the K1 in particular). Thus we embarked on another study with a 3D model to study the baroclinic effects on the residual and several selected tidal constituents. The 3D model uses a harmonic expansion in time and a finite element discretization in space. All nonlinear terms are retained, including quadratic bottom stress, advection and wave transport (continuity nonlinearity). The equations are solved as a global and a local problem, where the global problem is the solution of the wave equation formulation of the shallow water equations, and the local problem is the solution of the momentum equation for the vertical velocity profile. These equations are coupled to the advection-diffusion equation for density so that density gradient forcing is included in the momentum equations. However, the study presented here describes diagnostic calculations for the baroclinic residual circulation only. The model is sufficiently efficient that it encourages sensitivity testing with a large number of model runs. In this sense, the model is akin to an extension of analytical solutions to the domain of irregular geometry and bottom topography where this parameter space can be explored in some detail. In particular, the consequences of the sigma coordinate system used by the model are explored. Test cases using an idealized representation of the continental shelf, shelf break and shelf slope, lead to an estimation of the velocity errors caused by interpolation errors inherent in the sigma coordinate system. On the basis of these estimates, the computational grid used in the 2D model is found to have inadequate resolution. Thus a new grid is generated with increased

  18. General circulation of the ocean

    SciTech Connect

    Abarbanel, H.D.I.; Young, W.R.

    1986-01-01

    This book is an analysis of the geophysics of ocean circulation and its interaction with the atmosphere. It reviews the new concepts and models which have emerged in the last five years, as well as classical theories and observations. The contributions cover topics such as: the observational basis for large-scale circulation, including surface and deep circulation and subtropical gyres; thermocline theories; inverse methods for ocean circulation; baroclinic theories of the wind-driven circulation; and single layer models. This volume sets the current research literature in context, and suggests promising avenues for future study.

  19. Investigation of the performance of the General Electric ADVANCE positron emission tomograph in 3D mode

    SciTech Connect

    Lewellen, T.K.; Kohlmyer, S.G.; Miyaoka, R.S.; Kaplan, M.S.; Stearns, C.W.; Schubert, S.F.

    1996-08-01

    Performance measurements of the General Electric ADVANCE Positron Emission Tomograph operating with the septa retracted (3D mode) were made. All reconstructions were performed with the GE ADVANCE 3D package. Performance tests were carried out with: the NEMA phantoms; a 3D Hoffman phantom; a Data Spectrum torso phantom with lung and cardiac inserts; and the Utah 3D evaluation phantom. Data collected included: transaxial and axial resolution, uniformity, recovery coefficients, count rate performance, dead time accuracy, and effect of scatter correction.

  20. Numerical 3D models support two distinct hydrothermal circulation systems at fast spreading ridges

    NASA Astrophysics Data System (ADS)

    Hasenclever, Jörg; Theissen-Krah, Sonja; Rüpke, Lars

    2013-04-01

    We present 3D numerical calculations of hydrothermal fluid flow at fast spreading ridges. The setup of the 3D models is based our previous 2D studies, in which we have coupled numerical models for crustal accretion and hydrothermal fluid flow. One result of these calculations is a crustal permeability field that leads to a thermal structure in the crust that matches seismic tomography data of the East Pacific Rise (EPR). The 1000°C isotherm obtained from the 2D results is now used as the lower boundary of the 3D model domain, while the upper boundary is a smoothed bathymetry of the EPR. The same permeability field as in the 2D models is used, with the highest permeability at the ridge axis and a decrease with both depth and distance to the ridge. Permeability is also reduced linearly between 600 and 1000°C. Using a newly developed parallel finite element code written in Matlab that solves for thermal evolution, fluid pressure and Darcy flow, we simulate the flow patterns of hydrothermal circulation in a segment of 5000m along-axis, 10000m across-axis and up to 5000m depth. We observe two distinct hydrothermal circulation systems: An on-axis system forming a series of vents with a spacing ranging from 100 to 500m that is recharged by nearby (100-200m) downflows on both sides of the ridge axis. Simultaneously a second system with much broader extensions both laterally and vertically exists off-axis. It is recharged by fluids intruding between 1500m to 5000m off-axis and sampling both upper and lower crust. These fluids are channeled in the deepest and hottest regions with high permeability and migrate up-slope following the 600°C isotherm until reaching the edge of the melt lens. Depending on the width of the melt lens these off-axis fluids either merge with the on-axis hydrothermal system or form separate vents. We observe separate off-axis vent fields if the magma lens half-width exceeds 1000m and confluence of both systems for half-widths smaller than 500m. For

  1. Development of generalized 3-D braiding machines for composite preforms

    NASA Technical Reports Server (NTRS)

    Huey, Cecil O., Jr.; Farley, Gary L.

    1993-01-01

    The operating principles of two prototype braiding machines for the production of generalized braid patterns are described. Both processes afford previously unachievable control of the interlacing of fibers within a textile structure that make them especially amenable to the fabrication of textile preforms for composite materials. They enable independent control of the motion of the individual fibers being woven, thereby enabling the greatest possible freedom in controlling fiber orientation within a structure. This freedom enables the designer to prescribe local fiber orientation to better optimize material performance. The processes have been implemented on a very small scale but at a level that demonstrates their practicality and the soundness of the principles governing their operation.

  2. LLNL Ocean General Circulation Model

    SciTech Connect

    Wickett, M. E.; Caldeira, K.; Duffy, P.

    2005-12-29

    The LLNL OGCM is a numerical ocean modeling tool for use in studying ocean circulation over a wide range of space and time scales, with primary applications to climate change and carbon cycle science.

  3. Development of generalized 3-D braiding machines for composite preforms

    NASA Astrophysics Data System (ADS)

    Huey, Cecil O., Jr.; Farley, Gary L.

    1992-10-01

    The development of prototype braiding machines for the production of generalized braid patterns is described. Mechanical operating principles and control strategies are presented for two prototype machines which have been fabricated and evaluated. Both machines represent advances over current fabrication techniques for composite materials by enabling nearly ideal control of fiber orientations within preform structures. They permit optimum design of parts that might be subjected to complex loads or that have complex forms. Further, they overcome both the lack of general control of produced fiber architectures and the complexity of other weaving processes that have been proposed for the same purpose. One prototype, the Farley braider, consists of an array of turntables that can be made to oscillate in 90 degree steps. Yarn ends are transported about the surface formed by the turntables by motorized tractors which are controlled through an optical link with the turntables and powered through electrical contact with the turntables. The necessary relative motions are produced by a series of linear tractor moves combined with a series of turntable rotations. As the tractors move about, they weave the yarn ends into the desired pattern. The second device, the shuttle plate braider, consists of a braiding surface formed by an array of stationary square sections, each separated from its neighbors by a gap. A plate beneath this surface is caused to reciprocate in two perpendicular directions, first in one direction and then in the other. This movement is made possibly by openings in the plate that clear short columns supporting the surface segments. Yarn ends are moved about the surface and interwoven by shuttles which engage the reciprocating plate as needed to yield the desired movements. Power and control signals are transmitted to the shuttles through electrical contact with the braiding surface. The shuttle plate is a passively driven prime mover that supplies the power

  4. Development of generalized 3-D braiding machines for composite preforms

    NASA Technical Reports Server (NTRS)

    Huey, Cecil O., Jr.; Farley, Gary L.

    1992-01-01

    The development of prototype braiding machines for the production of generalized braid patterns is described. Mechanical operating principles and control strategies are presented for two prototype machines which have been fabricated and evaluated. Both machines represent advances over current fabrication techniques for composite materials by enabling nearly ideal control of fiber orientations within preform structures. They permit optimum design of parts that might be subjected to complex loads or that have complex forms. Further, they overcome both the lack of general control of produced fiber architectures and the complexity of other weaving processes that have been proposed for the same purpose. One prototype, the Farley braider, consists of an array of turntables that can be made to oscillate in 90 degree steps. Yarn ends are transported about the surface formed by the turntables by motorized tractors which are controlled through an optical link with the turntables and powered through electrical contact with the turntables. The necessary relative motions are produced by a series of linear tractor moves combined with a series of turntable rotations. As the tractors move about, they weave the yarn ends into the desired pattern. The second device, the shuttle plate braider, consists of a braiding surface formed by an array of stationary square sections, each separated from its neighbors by a gap. A plate beneath this surface is caused to reciprocate in two perpendicular directions, first in one direction and then in the other. This movement is made possibly by openings in the plate that clear short columns supporting the surface segments. Yarn ends are moved about the surface and interwoven by shuttles which engage the reciprocating plate as needed to yield the desired movements. Power and control signals are transmitted to the shuttles through electrical contact with the braiding surface. The shuttle plate is a passively driven prime mover that supplies the power

  5. Combining Abundance/Temperature Retrieval with 3D Atmospheric Circulation Simulations of Hot Jupiters

    NASA Astrophysics Data System (ADS)

    Heng, Kevin

    2011-09-01

    The atmospheres of hot Jupiters are three-dimensional, non-linear entities and understanding them requires the construction of a hierarchy of models of varying sophistication. Since previous work has either focused on the atmospheric dynamics or implemented multi-band radiative transfer, a reasonable approach is to combine the treatment of 3D dynamics with dual-band radiative transfer, where the assumption is that the stellar irradiation and re-emitted radiation from the exoplanet are at distinct wavelengths. I report on the successful implementation of such a setup and demonstrate how it can be used to compute self-consistent temperature-pressure profiles on both the day and night sides of a hot Jupiter, as well as zonal-wind profiles, circulation cell patterns and the angular/temporal offset of the hotspot from the substellar point. In particular, the hotspot offset should aid us in distinguishing between different types of hot Jupiter atmospheres. Together with N. Madhusudhan, we combine the dual-band simulation technique with the abundance/temperature retrieval method of Madhusudhan & Seager, by empirically constraining a range of values for the broad-band opacities which are consistent with the current observations. The advantage of our novel method is that the range of opacities used improves with time as the observations get better. The ability to thoroughly, efficiently and systematically explore the interplay between atmospheric dynamics, radiation and synthetic spectra is an important step forward, as it prepares us for the theoretical interpretation of exoplanetary spectra which will be obtained by future space-based missions such as JWST and EChO. I acknowledge generous support from the Zwicky Prize Fellowship and the Star and Planet Formation Group (PI: Michael Meyer) at ETH Zurich.

  6. A new estimate of the global 3D geostrophic ocean circulation based on satellite data and in-situ measurements

    NASA Astrophysics Data System (ADS)

    Mulet, S.; Rio, M.-H.; Mignot, A.; Guinehut, S.; Morrow, R.

    2012-11-01

    A new estimate of the Global Ocean 3D geostrophic circulation from the surface down to 1500 m depth (Surcouf3D) has been computed for the 1993-2008 period using an observation-based approach that combines altimetry with temperature and salinity through the thermal wind equation. The validity of this simple approach was tested using a consistent dataset from a model reanalysis. Away from the boundary layers, errors are less than 10% in most places, which indicate that the thermal wind equation is a robust approximation to reconstruct the 3D oceanic circulation in the ocean interior. The Surcouf3D current field was validated in the Atlantic Ocean against in-situ observations. We considered the ANDRO current velocities deduced at 1000 m depth from Argo float displacements as well as velocity measurements at 26.5°N from the RAPID-MOCHA current meter array. The Surcouf3D currents show similar skill to the 3D velocities from the GLORYS Mercator Ocean reanalysis in reproducing the amplitude and variability of the ANDRO currents. In the upper 1000 m, high correlations are also found with in-situ velocities measured by the RAPID-MOCHA current meters. The Surcouf3D current field was then used to compute estimates of the Atlantic Meridional Overturning Circulation (AMOC) through the 25°N section, showing good comparisons with hydrographic sections from 1998 and 2004. Monthly averaged AMOC time series are also consistent with the RAPID-MOCHA array and with the GLORYS Mercator Ocean reanalysis over the April 2004-September 2007 period. Finally a 15 years long time series of monthly estimates of the AMOC was computed. The AMOC strength has a mean value of 16 Sv with an annual (resp. monthly) standard deviation of 2.4 Sv (resp. 7.1 Sv) over the 1993-2008 period. The time series, characterized by a strong variability, shows no significant trend.

  7. Implementation of algebraic stress models in a general 3-D Navier-Stokes method (PAB3D)

    NASA Technical Reports Server (NTRS)

    Abdol-Hamid, Khaled S.

    1995-01-01

    A three-dimensional multiblock Navier-Stokes code, PAB3D, which was developed for propulsion integration and general aerodynamic analysis, has been used extensively by NASA Langley and other organizations to perform both internal (exhaust) and external flow analysis of complex aircraft configurations. This code was designed to solve the simplified Reynolds Averaged Navier-Stokes equations. A two-equation k-epsilon turbulence model has been used with considerable success, especially for attached flows. Accurate predicting of transonic shock wave location and pressure recovery in separated flow regions has been more difficult. Two algebraic Reynolds stress models (ASM) have been recently implemented in the code that greatly improved the code's ability to predict these difficult flow conditions. Good agreement with Direct Numerical Simulation (DNS) for a subsonic flat plate was achieved with ASM's developed by Shih, Zhu, and Lumley and Gatski and Speziale. Good predictions were also achieved at subsonic and transonic Mach numbers for shock location and trailing edge boattail pressure recovery on a single-engine afterbody/nozzle model.

  8. LayTracks3D: A new approach for meshing general solids using medial axis transform

    SciTech Connect

    Quadros, William Roshan

    2015-08-22

    This study presents an extension of the all-quad meshing algorithm called LayTracks to generate high quality hex-dominant meshes of general solids. LayTracks3D uses the mapping between the Medial Axis (MA) and the boundary of the 3D domain to decompose complex 3D domains into simpler domains called Tracks. Tracks in 3D have no branches and are symmetric, non-intersecting, orthogonal to the boundary, and the shortest path from the MA to the boundary. These properties of tracks result in desired meshes with near cube shape elements at the boundary, structured mesh along the boundary normal with any irregular nodes restricted to the MA, and sharp boundary feature preservation. The algorithm has been tested on a few industrial CAD models and hex-dominant meshes are shown in the Results section. Work is underway to extend LayTracks3D to generate all-hex meshes.

  9. Generalized recovery algorithm for 3D super-resolution microscopy using rotating point spread functions

    PubMed Central

    Shuang, Bo; Wang, Wenxiao; Shen, Hao; Tauzin, Lawrence J.; Flatebo, Charlotte; Chen, Jianbo; Moringo, Nicholas A.; Bishop, Logan D. C.; Kelly, Kevin F.; Landes, Christy F.

    2016-01-01

    Super-resolution microscopy with phase masks is a promising technique for 3D imaging and tracking. Due to the complexity of the resultant point spread functions, generalized recovery algorithms are still missing. We introduce a 3D super-resolution recovery algorithm that works for a variety of phase masks generating 3D point spread functions. A fast deconvolution process generates initial guesses, which are further refined by least squares fitting. Overfitting is suppressed using a machine learning determined threshold. Preliminary results on experimental data show that our algorithm can be used to super-localize 3D adsorption events within a porous polymer film and is useful for evaluating potential phase masks. Finally, we demonstrate that parallel computation on graphics processing units can reduce the processing time required for 3D recovery. Simulations reveal that, through desktop parallelization, the ultimate limit of real-time processing is possible. Our program is the first open source recovery program for generalized 3D recovery using rotating point spread functions. PMID:27488312

  10. MERIDIONAL CIRCULATION DYNAMICS FROM 3D MAGNETOHYDRODYNAMIC GLOBAL SIMULATIONS OF SOLAR CONVECTION

    SciTech Connect

    Passos, Dário; Charbonneau, Paul; Miesch, Mark

    2015-02-10

    The form of solar meridional circulation is a very important ingredient for mean field flux transport dynamo models. However, a shroud of mystery still surrounds this large-scale flow, given that its measurement using current helioseismic techniques is challenging. In this work, we use results from three-dimensional global simulations of solar convection to infer the dynamical behavior of the established meridional circulation. We make a direct comparison between the meridional circulation that arises in these simulations and the latest observations. Based on our results, we argue that there should be an equatorward flow at the base of the convection zone at mid-latitudes, below the current maximum depth helioseismic measures can probe (0.75 R{sub ⊙}). We also provide physical arguments to justify this behavior. The simulations indicate that the meridional circulation undergoes substantial changes in morphology as the magnetic cycle unfolds. We close by discussing the importance of these dynamical changes for current methods of observation which involve long averaging periods of helioseismic data. Also noteworthy is the fact that these topological changes indicate a rich interaction between magnetic fields and plasma flows, which challenges the ubiquitous kinematic approach used in the vast majority of mean field dynamo simulations.

  11. Measurements of 3-D Circulation and Dispersion in Skagit Bay from Lagrangian Drifters

    DTIC Science & Technology

    2011-05-02

    target was to sample the Tijuana river plume during major ram events, the rarity of the latter hindered our efforts. The deployments of 01/13/2009...within the plume of the Tijuana River as well as the circulation in adjacent coastal sea. The third objective was to redesign and re-build the firmware...frequency GPS. Approach To achieve our first objective we targeted RD deployments during significant rain events at the mouth of the Tijuana River, off La

  12. a Unified Approach for 3d Generalization of Building Models in Citygml

    NASA Astrophysics Data System (ADS)

    Baig, S. U.; Rahman, A. A.

    2013-05-01

    Task-specific applications demand abstractions (generalized) 3D scenes of 3D models to be used for visualization and analysis purposes. Therefore, lower LoDs (level-of-details) from higher LoDs need to be made available to these applications. A unified generalization framework is proposed to derive multiple LoDs (LoD3-LoD1) taking both semantics and geometric aspects of 3D buildings modelled in CityGML (City Geography Markup Language) into account. For this purpose, interior structures of 3D objects at LoD4 are removed to derive LoD3 and openings (door, windows) are removed from LoD3 to derive LoD2. Remaining parts such as outer installations and walls are projected onto the ground and simplified based on CityGML generalization specifications. Algorithms for simplification with the aim to derive LoD1 from LoD2 are implemented and tested on a number of buildings of Putrajaya city, Malaysia.The experiments shows that elimination of important part (s) or merging could be avoided by applying semantic-based removal of objects at different LoDs.

  13. LayTracks3D: A new approach for meshing general solids using medial axis transform

    DOE PAGES

    Quadros, William Roshan

    2015-08-22

    This study presents an extension of the all-quad meshing algorithm called LayTracks to generate high quality hex-dominant meshes of general solids. LayTracks3D uses the mapping between the Medial Axis (MA) and the boundary of the 3D domain to decompose complex 3D domains into simpler domains called Tracks. Tracks in 3D have no branches and are symmetric, non-intersecting, orthogonal to the boundary, and the shortest path from the MA to the boundary. These properties of tracks result in desired meshes with near cube shape elements at the boundary, structured mesh along the boundary normal with any irregular nodes restricted to themore » MA, and sharp boundary feature preservation. The algorithm has been tested on a few industrial CAD models and hex-dominant meshes are shown in the Results section. Work is underway to extend LayTracks3D to generate all-hex meshes.« less

  14. 3D-Simulation Of Concentration Distributions Inside Large-Scale Circulating Fluidized Bed Combustors

    NASA Astrophysics Data System (ADS)

    Wischnewski, R.; Ratschow, L.; Hartge, E. U.; Werthe, J.

    With increasing size of modern CFB combustors the lateral mixing of fuels and secondary air gains more and more importance. Strong concentration gradients, which result from improper lateral mixing, can lead to operational problems, high flue gas emissions and lower boiler efficiencies. A 3D-model for the simulation of local gas and solids concentrations inside industrial-sized CFB boilers has been developed. The model is based on a macroscopic approach and considers all major mechanisms during fuel spreading and subsequent combustion of char and volatiles. Typical characteristics of modern boilers like staged combustion, a smaller cross-sectional area in the lower section of the combustion chamber and the co-combustion of additional fuels with coal can be considered. The 252 MWth combustor of Stadtwerke Duisburg AG is used for the validation of the model. A comprehensive picture of the local conditions inside the combustion chamber is achieved by the combination of local gas measurements and the three-dimensional simulation of concentration distributions.

  15. Generalized total least squares prediction algorithm for universal 3D similarity transformation

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Li, Jiancheng; Liu, Chao; Yu, Jie

    2017-02-01

    Three-dimensional (3D) similarity datum transformation is extensively applied to transform coordinates from GNSS-based datum to a local coordinate system. Recently, some total least squares (TLS) algorithms have been successfully developed to solve the universal 3D similarity transformation problem (probably with big rotation angles and an arbitrary scale ratio). However, their procedures of the parameter estimation and new point (non-common point) transformation were implemented separately, and the statistical correlation which often exists between the common and new points in the original coordinate system was not considered. In this contribution, a generalized total least squares prediction (GTLSP) algorithm, which implements the parameter estimation and new point transformation synthetically, is proposed. All of the random errors in the original and target coordinates, and their variance-covariance information will be considered. The 3D transformation model in this case is abstracted as a kind of generalized errors-in-variables (EIV) model and the equation for new point transformation is incorporated into the functional model as well. Then the iterative solution is derived based on the Gauss-Newton approach of nonlinear least squares. The performance of GTLSP algorithm is verified in terms of a simulated experiment, and the results show that GTLSP algorithm can improve the statistical accuracy of the transformed coordinates compared with the existing TLS algorithms for 3D similarity transformation.

  16. Generalized Hough transform based time invariant action recognition with 3D pose information

    NASA Astrophysics Data System (ADS)

    Muench, David; Huebner, Wolfgang; Arens, Michael

    2014-10-01

    Human action recognition has emerged as an important field in the computer vision community due to its large number of applications such as automatic video surveillance, content based video-search and human robot interaction. In order to cope with the challenges that this large variety of applications present, recent research has focused more on developing classifiers able to detect several actions in more natural and unconstrained video sequences. The invariance discrimination tradeoff in action recognition has been addressed by utilizing a Generalized Hough Transform. As a basis for action representation we transform 3D poses into a robust feature space, referred to as pose descriptors. For each action class a one-dimensional temporal voting space is constructed. Votes are generated from associating pose descriptors with their position in time relative to the end of an action sequence. Training data consists of manually segmented action sequences. In the detection phase valid human 3D poses are assumed as input, e.g. originating from 3D sensors or monocular pose reconstruction methods. The human 3D poses are normalized to gain view-independence and transformed into (i) relative limb-angle space to ensure independence of non-adjacent joints or (ii) geometric features. In (i) an action descriptor consists of the relative angles between limbs and their temporal derivatives. In (ii) the action descriptor consists of different geometric features. In order to circumvent the problem of time-warping we propose to use a codebook of prototypical 3D poses which is generated from sample sequences of 3D motion capture data. This idea is in accordance with the concept of equivalence classes in action space. Results of the codebook method are presented using the Kinect sensor and the CMU Motion Capture Database.

  17. Generalization of the tensor renormalization group approach to 3-D or higher dimensions

    NASA Astrophysics Data System (ADS)

    Teng, Peiyuan

    2017-04-01

    In this paper, a way of generalizing the tensor renormalization group (TRG) is proposed. Mathematically, the connection between patterns of tensor renormalization group and the concept of truncation sequence in polytope geometry is discovered. A theoretical contraction framework is therefore proposed. Furthermore, the canonical polyadic decomposition is introduced to tensor network theory. A numerical verification of this method on the 3-D Ising model is carried out.

  18. CONTINUOUS-ENERGY MONTE CARLO METHODS FOR CALCULATING GENERALIZED RESPONSE SENSITIVITIES USING TSUNAMI-3D

    SciTech Connect

    Perfetti, Christopher M; Rearden, Bradley T

    2014-01-01

    This work introduces a new approach for calculating sensitivity coefficients for generalized neutronic responses to nuclear data uncertainties using continuous-energy Monte Carlo methods. The approach presented in this paper, known as the GEAR-MC method, allows for the calculation of generalized sensitivity coefficients for multiple responses in a single Monte Carlo calculation with no nuclear data perturbations or knowledge of nuclear covariance data. The theory behind the GEAR-MC method is presented here, and proof of principle is demonstrated by using the GEAR-MC method to calculate sensitivity coefficients for responses in several 3D, continuous-energy Monte Carlo applications.

  19. A Generalized Approach to the Modeling and Analysis of 3D Surface Morphology in Organisms

    PubMed Central

    Pappas, Janice L.; Miller, Daniel J.

    2013-01-01

    The surface geometry of an organism represents the boundary of its three-dimensional (3D) form and can be used as a proxy for the phenotype. A mathematical approach is presented that describes surface morphology using parametric 3D equations with variables expressed as x, y, z in terms of parameters u, v. Partial differentiation of variables with respect to parameters yields elements of the Jacobian representing tangent lines and planes of every point on the surface. Jacobian elements provide a compact size-free summary of the entire surface, and can be used as variables in principal components analysis to produce a morphospace. Mollusk and echinoid models are generated to demonstrate that whole organisms can be represented in a common morphospace, regardless of differences in size, geometry, and taxonomic affinity. Models can be used to simulate theoretical forms, novel morphologies, and patterns of phenotypic variation, and can also be empirically-based by designing them with reference to actual forms using reverse engineering principles. Although this study uses the Jacobian to summarize models, they can also be analyzed with 3D methods such as eigensurface, spherical harmonics, wavelet analysis, and geometric morphometrics. This general approach should prove useful for exploring broad questions regarding morphological evolution and variation. PMID:24204866

  20. Parallel implementation of the FETI-DPEM algorithm for general 3D EM simulations

    NASA Astrophysics Data System (ADS)

    Li, Yu-Jia; Jin, Jian-Ming

    2009-05-01

    A parallel implementation of the electromagnetic dual-primal finite element tearing and interconnecting algorithm (FETI-DPEM) is designed for general three-dimensional (3D) electromagnetic large-scale simulations. As a domain decomposition implementation of the finite element method, the FETI-DPEM algorithm provides fully decoupled subdomain problems and an excellent numerical scalability, and thus is well suited for parallel computation. The parallel implementation of the FETI-DPEM algorithm on a distributed-memory system using the message passing interface (MPI) is discussed in detail along with a few practical guidelines obtained from numerical experiments. Numerical examples are provided to demonstrate the efficiency of the parallel implementation.

  1. Enhanced high dynamic range 3D shape measurement based on generalized phase-shifting algorithm

    NASA Astrophysics Data System (ADS)

    Wang, Minmin; Du, Guangliang; Zhou, Canlin; Zhang, Chaorui; Si, Shuchun; Li, Hui; Lei, Zhenkun; Li, YanJie

    2017-02-01

    Measuring objects with large reflectivity variations across their surface is one of the open challenges in phase measurement profilometry (PMP). Saturated or dark pixels in the deformed fringe patterns captured by the camera will lead to phase fluctuations and errors. Jiang et al. proposed a high dynamic range real-time three-dimensional (3D) shape measurement method (Jiang et al., 2016) [17] that does not require changing camera exposures. Three inverted phase-shifted fringe patterns are used to complement three regular phase-shifted fringe patterns for phase retrieval whenever any of the regular fringe patterns are saturated. Nonetheless, Jiang's method has some drawbacks: (1) the phases of saturated pixels are estimated by different formulas on a case by case basis; in other words, the method lacks a universal formula; (2) it cannot be extended to the four-step phase-shifting algorithm, because inverted fringe patterns are the repetition of regular fringe patterns; (3) for every pixel in the fringe patterns, only three unsaturated intensity values can be chosen for phase demodulation, leaving the other unsaturated ones idle. We propose a method to enhance high dynamic range 3D shape measurement based on a generalized phase-shifting algorithm, which combines the complementary techniques of inverted and regular fringe patterns with a generalized phase-shifting algorithm. Firstly, two sets of complementary phase-shifted fringe patterns, namely the regular and the inverted fringe patterns, are projected and collected. Then, all unsaturated intensity values at the same camera pixel from two sets of fringe patterns are selected and employed to retrieve the phase using a generalized phase-shifting algorithm. Finally, simulations and experiments are conducted to prove the validity of the proposed method. The results are analyzed and compared with those of Jiang's method, demonstrating that our method not only expands the scope of Jiang's method, but also improves

  2. HERO - A 3D general relativistic radiative post-processor for accretion discs around black holes

    NASA Astrophysics Data System (ADS)

    Zhu, Yucong; Narayan, Ramesh; Sadowski, Aleksander; Psaltis, Dimitrios

    2015-08-01

    HERO (Hybrid Evaluator for Radiative Objects) is a 3D general relativistic radiative transfer code which has been tailored to the problem of analysing radiation from simulations of relativistic accretion discs around black holes. HERO is designed to be used as a post-processor. Given some fixed fluid structure for the disc (i.e. density and velocity as a function of position from a hydrodynamic or magnetohydrodynamic simulation), the code obtains a self-consistent solution for the radiation field and for the gas temperatures using the condition of radiative equilibrium. The novel aspect of HERO is that it combines two techniques: (1) a short-characteristics (SC) solver that quickly converges to a self-consistent disc temperature and radiation field, with (2) a long-characteristics (LC) solver that provides a more accurate solution for the radiation near the photosphere and in the optically thin regions. By combining these two techniques, we gain both the computational speed of SC and the high accuracy of LC. We present tests of HERO on a range of 1D, 2D, and 3D problems in flat space and show that the results agree well with both analytical and benchmark solutions. We also test the ability of the code to handle relativistic problems in curved space. Finally, we discuss the important topic of ray defects, a major limitation of the SC method, and describe our strategy for minimizing the induced error.

  3. Two reconstruction procedures for a 3D phaseless inverse scattering problem for the generalized Helmholtz equation

    NASA Astrophysics Data System (ADS)

    Klibanov, Michael V.; Romanov, Vladimir G.

    2016-01-01

    The 3D inverse scattering problem of the reconstruction of the unknown dielectric permittivity in the generalized Helmholtz equation is considered. Applications are in imaging of nanostructures and biological cells. The main difference with the conventional inverse scattering problems is that only the modulus of the scattering wave field is measured. The phase is not measured. The initializing wave field is the incident plane wave. On the other hand, in the previous recent works of the authors about the ‘phaseless topic’ the case of the point source was considered (Klibanov and Romanov 2015 J. Inverse Ill-Posed Problem 23 415-28 J. Inverse Ill-Posed Problem 23 187-93). Two reconstruction procedures are developed.

  4. GPU Developments for General Circulation Models

    NASA Astrophysics Data System (ADS)

    Appleyard, Jeremy; Posey, Stan; Ponder, Carl; Eaton, Joe

    2014-05-01

    Current trends in high performance computing (HPC) are moving towards the use of graphics processing units (GPUs) to achieve speedups through the extraction of fine-grain parallelism of application software. GPUs have been developed exclusively for computational tasks as massively-parallel co-processors to the CPU, and during 2013 an extensive set of new HPC architectural features were developed in a 4th generation of NVIDIA GPUs that provide further opportunities for GPU acceleration of general circulation models used in climate science and numerical weather prediction. Today computational efficiency and simulation turnaround time continue to be important factors behind scientific decisions to develop models at higher resolutions and deploy increased use of ensembles. This presentation will examine the current state of GPU parallel developments for stencil based numerical operations typical of dynamical cores, and introduce new GPU-based implicit iterative schemes with GPU parallel preconditioning and linear solvers based on ILU, Krylov methods, and multigrid. Several GCMs show substantial gain in parallel efficiency from second-level fine-grain parallelism under first-level distributed memory parallel through a hybrid parallel implementation. Examples are provided relevant to science-scale HPC practice of CPU-GPU system configurations based on model resolution requirements of a particular simulation. Performance results compare use of the latest conventional CPUs with and without GPU acceleration. Finally a forward looking discussion is provided on the roadmap of GPU hardware, software, tools, and programmability for GCM development.

  5. Snow hydrology in a general circulation model

    NASA Technical Reports Server (NTRS)

    Marshall, Susan; Roads, John O.; Glatzmaier, Gary

    1994-01-01

    A snow hydrology has been implemented in an atmospheric general circulation model (GCM). The snow hydrology consists of parameterizations of snowfall and snow cover fraction, a prognostic calculation of snow temperature, and a model of the snow mass and hydrologic budgets. Previously, only snow albedo had been included by a specified snow line. A 3-year GCM simulation with this now more complete surface hydrology is compared to a previous GCM control run with the specified snow line, as well as with observations. In particular, the authors discuss comparisons of the atmospheric and surface hydrologic budgets and the surface energy budget for U.S. and Canadian areas. The new snow hydrology changes the annual cycle of the surface moisture and energy budgets in the model. There is a noticeable shift in the runoff maximum from winter in the control run to spring in the snow hydrology run. A substantial amount of GCM winter precipitation is now stored in the seasonal snowpack. Snow cover also acts as an important insulating layer between the atmosphere and the ground. Wintertime soil temperatures are much higher in the snow hydrology experiment than in the control experiment. Seasonal snow cover is important for dampening large fluctuations in GCM continental skin temperature during the Northern Hemisphere winter. Snow depths and snow extent show good agreement with observations over North America. The geographic distribution of maximum depths is not as well simulated by the model due, in part, to the coarse resolution of the model. The patterns of runoff are qualitatively and quantitatively similar to observed patterns of streamflow averaged over the continental United States. The seasonal cycles of precipitation and evaporation are also reasonably well simulated by the model, although their magnitudes are larger than is observed. This is due, in part, to a cold bias in this model, which results in a dry model atmosphere and enhances the hydrologic cycle everywhere.

  6. Snow hydrology in a general circulation model

    SciTech Connect

    Marshall, S. ); Roads, J.O. ); Glatzmaier, G. )

    1994-08-01

    A snow hydrology has been implemented in an atmospheric general circulation model (GCM). The snow hydrology consists of parameterizations of snowfall and snow cover fraction, a prognostic calculation of snow temperature, and a model of the snow mass and hydrologic budgets. Previously, only snow albedo had been included. A 3-year GCM simulation with this more complete surface hydrology is compared to a previous GCM control run with the specified snow line, as well as with observations. In particular, the authors discuss comparisons of the atmospheric and surface hydrologic budgets and the surface energy budget for U.S. and Canadian areas. The new snow hydrology changes the annual cycle of the surface moisture and energy budgets in the model. There is a noticeable shift in the runoff maximum from winter in the control run to spring in the snow hydrology run. A substantial amount of GCM winter precipitation is now stored in the seasonal snowpack. Snow cover also acts as an important insulating layer between the atmosphere and the ground. Wintertime soil temperatures are much higher in the snow, hydrology experiment than in the control experiment. Seasonal snow cover is important for dampening large fluctuations in GCM continental skin temperature during the Northern Hemisphere winter. Snow depths and snow extent show good agreement with observations over North America. The geographic distribution of maximum depths is not as well simulated by the model due, in part, to the coarse resolution of the model. The patterns of runoff are qualitatively and quantitatively similar to observed patterns of streamflow averaged over the continental United States. The seasonal cycles of precipitation and evaporation are also reasonably well simulated by the model, although their magnitudes are larger than is observed. This is due, in part, to a cold bias in this model, which results in a dry model atmosphere and enhances the hydrologic cycle everywhere. 52 refs., 13 figs., 5 tabs.

  7. General application of rapid 3-D digitizing and tool path generation for complex shapes

    SciTech Connect

    Kwok, K.S.; Loucks, C.S.; Driessen, B.J.

    1997-09-01

    A system for automatic tool path generation was developed at Sandia National Laboratories for finish machining operations. The system consists of a commercially available 5-axis milling machine controlled by Sandia developed software. This system was used to remove overspray on cast turbine blades. A laser-based, structured-light sensor, mounted on a tool holder, is used to collect 3D data points around the surface of the turbine blade. Using the digitized model of the blade, a tool path is generated which will drive a 0.375 inch grinding pin around the tip of the blade. A fuzzified digital filter was developed to properly eliminate false sensor readings caused by burrs, holes and overspray. The digital filter was found to successfully generate the correct tool path for a blade with intentionally scanned holes and defects. The fuzzified filter improved the computation efficiency by a factor of 25. For application to general parts, an adaptive scanning algorithm was developed and presented with simulation and experimental results. A right pyramid and an ellipsoid were scanned successfully with the adaptive algorithm in simulation studies. In actual experiments, a nose cone and a turbine blade were successfully scanned. A complex shaped turbine blade was successfully scanned and finished machined using these algorithms.

  8. HEROIC: 3D general relativistic radiative post-processor with comptonization for black hole accretion discs

    NASA Astrophysics Data System (ADS)

    Narayan, Ramesh; Zhu, Yucong; Psaltis, Dimitrios; Saḑowski, Aleksander

    2016-03-01

    We describe Hybrid Evaluator for Radiative Objects Including Comptonization (HEROIC), an upgraded version of the relativistic radiative post-processor code HERO described in a previous paper, but which now Includes Comptonization. HEROIC models Comptonization via the Kompaneets equation, using a quadratic approximation for the source function in a short characteristics radiation solver. It employs a simple form of accelerated lambda iteration to handle regions of high scattering opacity. In addition to solving for the radiation field, HEROIC also solves for the gas temperature by applying the condition of radiative equilibrium. We present benchmarks and tests of the Comptonization module in HEROIC with simple 1D and 3D scattering problems. We also test the ability of the code to handle various relativistic effects using model atmospheres and accretion flows in a black hole space-time. We present two applications of HEROIC to general relativistic magnetohydrodynamics simulations of accretion discs. One application is to a thin accretion disc around a black hole. We find that the gas below the photosphere in the multidimensional HEROIC solution is nearly isothermal, quite different from previous solutions based on 1D plane parallel atmospheres. The second application is to a geometrically thick radiation-dominated accretion disc accreting at 11 times the Eddington rate. Here, the multidimensional HEROIC solution shows that, for observers who are on axis and look down the polar funnel, the isotropic equivalent luminosity could be more than 10 times the Eddington limit, even though the spectrum might still look thermal and show no signs of relativistic beaming.

  9. Sensitivity simulations of superparameterised convection in a general circulation model

    NASA Astrophysics Data System (ADS)

    Rybka, Harald; Tost, Holger

    2015-04-01

    Cloud Resolving Models (CRMs) covering a horizontal grid spacing from a few hundred meters up to a few kilometers have been used to explicitly resolve small-scale and mesoscale processes. Special attention has been paid to realistically represent cloud dynamics and cloud microphysics involving cloud droplets, ice crystals, graupel and aerosols. The entire variety of physical processes on the small-scale interacts with the larger-scale circulation and has to be parameterised on the coarse grid of a general circulation model (GCM). Since more than a decade an approach to connect these two types of models which act on different scales has been developed to resolve cloud processes and their interactions with the large-scale flow. The concept is to use an ensemble of CRM grid cells in a 2D or 3D configuration in each grid cell of the GCM to explicitly represent small-scale processes avoiding the use of convection and large-scale cloud parameterisations which are a major source for uncertainties regarding clouds. The idea is commonly known as superparameterisation or cloud-resolving convection parameterisation. This study presents different simulations of an adapted Earth System Model (ESM) connected to a CRM which acts as a superparameterisation. Simulations have been performed with the ECHAM/MESSy atmospheric chemistry (EMAC) model comparing conventional GCM runs (including convection and large-scale cloud parameterisations) with the improved superparameterised EMAC (SP-EMAC) modeling one year with prescribed sea surface temperatures and sea ice content. The sensitivity of atmospheric temperature, precipiation patterns, cloud amount and types is observed changing the embedded CRM represenation (orientation, width, no. of CRM cells, 2D vs. 3D). Additionally, we also evaluate the radiation balance with the new model configuration, and systematically analyse the impact of tunable parameters on the radiation budget and hydrological cycle. Furthermore, the subgrid

  10. Artificial intelligence (AI)-based relational matching and multimodal medical image fusion: generalized 3D approaches

    NASA Astrophysics Data System (ADS)

    Vajdic, Stevan M.; Katz, Henry E.; Downing, Andrew R.; Brooks, Michael J.

    1994-09-01

    A 3D relational image matching/fusion algorithm is introduced. It is implemented in the domain of medical imaging and is based on Artificial Intelligence paradigms--in particular, knowledge base representation and tree search. The 2D reference and target images are selected from 3D sets and segmented into non-touching and non-overlapping regions, using iterative thresholding and/or knowledge about the anatomical shapes of human organs. Selected image region attributes are calculated. Region matches are obtained using a tree search, and the error is minimized by evaluating a `goodness' of matching function based on similarities of region attributes. Once the matched regions are found and the spline geometric transform is applied to regional centers of gravity, images are ready for fusion and visualization into a single 3D image of higher clarity.

  11. CFL3D Version 6.4-General Usage and Aeroelastic Analysis

    NASA Technical Reports Server (NTRS)

    Bartels, Robert E.; Rumsey, Christopher L.; Biedron, Robert T.

    2006-01-01

    This document contains the course notes on the computational fluid dynamics code CFL3D version 6.4. It is intended to provide from basic to advanced users the information necessary to successfully use the code for a broad range of cases. Much of the course covers capability that has been a part of previous versions of the code, with material compiled from a CFL3D v5.0 manual and from the CFL3D v6 web site prior to the current release. This part of the material is presented to users of the code not familiar with computational fluid dynamics. There is new capability in CFL3D version 6.4 presented here that has not previously been published. There are also outdated features no longer used or recommended in recent releases of the code. The information offered here supersedes earlier manuals and updates outdated usage. Where current usage supersedes older versions, notation of that is made. These course notes also provides hints for usage, code installation and examples not found elsewhere.

  12. Construction of 3-D Audio Systems: Background, Research, and General Requirements

    DTIC Science & Technology

    2008-10-01

    may be more important to have a spectrum that contains some constant bands with high amplitude (Blauert, 1969/70; Sextant , 1997). In a comparison of...Technology. Retrieved October 2, 2006, from http://www.sensaura.com Sextant . (1997). AUDIS multipurpose AUditory DISplay for 3-D hearing applications

  13. General circulation of the South Atlantic between 5 deg N and 35 deg S

    NASA Technical Reports Server (NTRS)

    Ollitrault, Michel; Mercier, H.; Blanc, F.; Letraon, L. Y.

    1991-01-01

    The TOPEX/POSEIDON altimeter will provide the temporal mean seal level. So, secondly, we propose to compute the difference between these two surfaces (mean sea level minus general circulation dynamic topography). The result will be an estimate of the marine geoid, which is time invariant for the 5-year period under consideration. If this geoid is precise enough, it will permit a description of seasonal variability of the large-scale surface circulation. If there happens to be enough float data, it may be possible to infer the first vertical modes of this variability. Thus the main goal of our investigation is to determine the 3-D general circulation of the South Atlantic and the large-scale seasonal fluctuations. This last objective, however, may be restricted to the western part of the South Atlantic because float deployments have been scheduled only in the Brasil basin.

  14. TractRender: a new generalized 3D medical image visualization and output platform

    NASA Astrophysics Data System (ADS)

    Hwang, Darryl H.; Tsao, Sinchai; Gajawelli, Niharika; Law, Meng; Lepore, Natasha

    2015-01-01

    Diffusion MRI allows us not only voxelized diffusion characteristics but also the potential to delineate neuronal fiber path through tractography. There is a dearth of flexible open source tractography software programs for visualizing these complicated 3D structures. Moreover, rendering these structures using various shading, lighting, and representations will result in vastly different graphical feel. In addition, the ability to output these objects in various formats increases the utility of this platform. We have created TractRender that leverages openGL features through Matlab, allowing for maximum ease of use but still maintain the flexibility of custom scene rendering.

  15. On the Critical One Component Regularity for 3-D Navier-Stokes System: General Case

    NASA Astrophysics Data System (ADS)

    Chemin, Jean-Yves; Zhang, Ping; Zhang, Zhifei

    2017-02-01

    Let us consider initial data {v_0} for the homogeneous incompressible 3D Navier-Stokes equation with vorticity belonging to {L^{3/2}\\cap L^2} . We prove that if the solution associated with {v_0} blows up at a finite time {T^star} , then for any p in {]4,∞[} , and any unit vector e of R^3, the L p norm in time with value in dot{H}^{1/2 + 2/p} of {(v|e)_{R^3}} blows up at {T^star}.

  16. On Evaluating circulation and temperature stratification under changing water levels in Lake Mead with a 3D hydrodynamic model

    NASA Astrophysics Data System (ADS)

    Li, Y.; Acharya, K.; Chen, D.; Stone, M.; Yu, Z.; Young, M.; Zhu, J.; Shafer, D. S.; Warwick, J. J.

    2009-12-01

    Sustained drought in the western United States since 2000 has led to a significant drop (about 35 meters) in the water level of Lake Mead, the largest reservoir by volume in United States. The drought combined with rapid urban development in southern Nevada and emergence of invasive species has threatened the water quality and ecological processes in Lake Mead. A three-dimensional hydrodynamic model, Environmental Fluid Dynamics Code (EFDC), was applied to investigate lake circulation and temperature stratification in parts of Lake Mead (Las Vegas Bay and Boulder Basin) under changing water levels. Besides the inflow from Las Vegas Wash and the Colorado River, the model considered atmospheric changes as well as the boundary conditions restricted by the operation of Hoover Dam. The model was calibrated and verified by using observed data including water level, velocity, and temperature from 2003 and 2005. The model was applied to study the hydrodynamic processes at water level 366.8 m (year 2000) and at water level 338.2 m (year 2008). The high-stage simulation described the pre-drought lake hydrodynamic processes while the low-stage simulation highlighted the drawdown impact on such processes. The results showed that both inflow and wind-driven mixing process played major roles in the thermal stratification and lake circulation in both cases. However, the atmospheric boundary played a more important role than inflow temperature on thermal stratification of Lake Mead during water level decline. Further, the thermal stratification regime and flow circulation pattern in shallow lake regions (e.g.., the Boulder Basin area) were most impacted. The temperature of the lake at the high-stage was more sensitive to inflow temperatures than at low-stage. Furthermore, flow velocities decreased with the decreasing water level due to reduction in wind impacts, particularly in shallow areas of the lake. Such changes in temperature and lake current due to present drought have a

  17. Holographic intravital microscopy for 2-D and 3-D imaging intact circulating blood cells in microcapillaries of live mice

    PubMed Central

    Kim, Kyoohyun; Choe, Kibaek; Park, Inwon; Kim, Pilhan; Park, YongKeun

    2016-01-01

    Intravital microscopy is an essential tool that reveals behaviours of live cells under conditions close to natural physiological states. So far, although various approaches for imaging cells in vivo have been proposed, most require the use of labelling and also provide only qualitative imaging information. Holographic imaging approach based on measuring the refractive index distributions of cells, however, circumvent these problems and offer quantitative and label-free imaging capability. Here, we demonstrate in vivo two- and three-dimensional holographic imaging of circulating blood cells in intact microcapillaries of live mice. The measured refractive index distributions of blood cells provide morphological and biochemical properties including three-dimensional cell shape, haemoglobin concentration, and haemoglobin contents at the individual cell level. With the present method, alterations in blood flow dynamics in live healthy and sepsis-model mice were also investigated. PMID:27605489

  18. Holographic intravital microscopy for 2-D and 3-D imaging intact circulating blood cells in microcapillaries of live mice

    NASA Astrophysics Data System (ADS)

    Kim, Kyoohyun; Choe, Kibaek; Park, Inwon; Kim, Pilhan; Park, Yongkeun

    2016-09-01

    Intravital microscopy is an essential tool that reveals behaviours of live cells under conditions close to natural physiological states. So far, although various approaches for imaging cells in vivo have been proposed, most require the use of labelling and also provide only qualitative imaging information. Holographic imaging approach based on measuring the refractive index distributions of cells, however, circumvent these problems and offer quantitative and label-free imaging capability. Here, we demonstrate in vivo two- and three-dimensional holographic imaging of circulating blood cells in intact microcapillaries of live mice. The measured refractive index distributions of blood cells provide morphological and biochemical properties including three-dimensional cell shape, haemoglobin concentration, and haemoglobin contents at the individual cell level. With the present method, alterations in blood flow dynamics in live healthy and sepsis-model mice were also investigated.

  19. Evaluation of axial and lateral modal superposition for general 3D drilling riser analysis

    SciTech Connect

    Burgdorf, O. Jr.

    1996-12-31

    A 3D partially non-linear transient fully-coupled riser analysis method is evaluated which uses modal superposition of independently extracted lateral and axial modes. Many lateral modes are combined with a lesser number axial modes to minimize adverse time step requirements typically induced by axial flexibility in direct time integration of beam-column elements. The reduced computer time option enables much faster parametric analysis of hang-off, as well as other connected drilling environments normally examined. Axial-lateral coupling is explicitly enforced and, resonance fidelity is preserved when excitation is near or coincident with axial natural periods. Reasonable correlation is shown with envelopes of test case dynamic responses published by API. Applicability of the method is limited by linearity assumptions indigenous to modal representation of dynamic deflections relative to a mean deflected shape. Sensitivities of incipient buckling during hang-off to axial damping and stiffness are described for an example 6,000 ft. deep composite drilling riser system.

  20. General solution of 2D and 3D superconducting quasiclassical systems: coalescing vortices and nanoisland geometries

    NASA Astrophysics Data System (ADS)

    Amundsen, Morten; Linder, Jacob

    2016-03-01

    An extension of quasiclassical Keldysh-Usadel theory to higher spatial dimensions than one is crucial in order to describe physical phenomena like charge/spin Hall effects and topological excitations like vortices and skyrmions, none of which are captured in one-dimensional models. We here present a numerical finite element method which solves the non-linearized 2D and 3D quasiclassical Usadel equation relevant for the diffusive regime. We show the application of this on three model systems with non-trivial geometries: (i) a bottlenecked Josephson junction with external flux, (ii) a nanodisk ferromagnet deposited on top of a superconductor and (iii) superconducting islands in contact with a ferromagnet. In case (i), we demonstrate that one may control externally not only the geometrical array in which superconducting vortices arrange themselves, but also to cause coalescence and tune the number of vortices. In case (iii), we show that the supercurrent path can be tailored by incorporating magnetic elements in planar Josephson junctions which also lead to a strong modulation of the density of states. The finite element method presented herein paves the way for gaining insight in physical phenomena which have remained largely unexplored due to the complexity of solving the full quasiclassical equations in higher dimensions.

  1. General solution of 2D and 3D superconducting quasiclassical systems: coalescing vortices and nanoisland geometries

    PubMed Central

    Amundsen, Morten; Linder, Jacob

    2016-01-01

    An extension of quasiclassical Keldysh-Usadel theory to higher spatial dimensions than one is crucial in order to describe physical phenomena like charge/spin Hall effects and topological excitations like vortices and skyrmions, none of which are captured in one-dimensional models. We here present a numerical finite element method which solves the non-linearized 2D and 3D quasiclassical Usadel equation relevant for the diffusive regime. We show the application of this on three model systems with non-trivial geometries: (i) a bottlenecked Josephson junction with external flux, (ii) a nanodisk ferromagnet deposited on top of a superconductor and (iii) superconducting islands in contact with a ferromagnet. In case (i), we demonstrate that one may control externally not only the geometrical array in which superconducting vortices arrange themselves, but also to cause coalescence and tune the number of vortices. In case (iii), we show that the supercurrent path can be tailored by incorporating magnetic elements in planar Josephson junctions which also lead to a strong modulation of the density of states. The finite element method presented herein paves the way for gaining insight in physical phenomena which have remained largely unexplored due to the complexity of solving the full quasiclassical equations in higher dimensions. PMID:26961921

  2. Diversity of Planetary Atmospheric Circulations and Climates in a Simplified General Circulation Model

    NASA Astrophysics Data System (ADS)

    Wang, Yixiong; Read, Peter

    2014-04-01

    The parametric dependence of terrestrial planetary atmospheric circulations and climates on characteristic parameters is studied. A simplified general circulation model-PUMA is employed to investigate the dynamic effects of planetary rotation rate and equator-to-pole temperature difference on the circulation and climate of terrestrial planetary atmospheres. Five different types of circulation regime are identified by mapping the experimental results in a 2-D parameter space defined by thermal Rossby number and frictional Taylor number. The effect of the transfer and redistribution of radiative energy is studied by building up a new two-band semi-gray radiative-convective scheme, which is capable of modelling greenhouse and anti-greenhouse effects while keeping the tunable parameters as few as possible. The results will provide insights into predicting the habitability of terrestrial exoplanets.

  3. A novel numerical flux for the 3D Euler equations with general equation of state

    NASA Astrophysics Data System (ADS)

    Toro, Eleuterio F.; Castro, Cristóbal E.; Lee, Bok Jik

    2015-12-01

    Here we extend the flux vector splitting approach recently proposed in E.F. Toro and M.E. Vázquez-Cendón (2012) [42]. The scheme was originally presented for the 1D Euler equations for ideal gases and its extension presented in this paper is threefold: (i) we solve the three-dimensional Euler equations on general meshes; (ii) we use a general equation of state; and (iii) we achieve high order of accuracy in both space and time through application of the semi-discrete ADER methodology on general meshes. The resulting methods are systematically assessed for accuracy, robustness and efficiency on a carefully selected suite of test problems. Formal high accuracy is assessed through convergence rates studies for schemes of up to 4th order of accuracy in both space and time on unstructured meshes.

  4. 3D profile measurements of objects by using zero order Generalized Morse Wavelet

    NASA Astrophysics Data System (ADS)

    Kocahan, Özlem; Durmuş, ćaǧla; Elmas, Merve Naz; Coşkun, Emre; Tiryaki, Erhan; Özder, Serhat

    2017-02-01

    Generalized Morse wavelets are proposed to evaluate the phase information from projected fringe pattern with the spatial carrier frequency in the x direction. The height profile of the object is determined through the phase change distribution by using the phase of the continuous wavelet transform. The phase distribution is extracted from the optical fringe pattern choosing zero order Generalized Morse Wavelet (GMW) as a mother wavelet. In this study, standard fringe projection technique is used for obtaining images. Experimental results for the GMW phase method are compared with the results of Morlet and Paul wavelet transform.

  5. Upper Boundary Extension of the NASA Ames Mars General Circulation Model

    NASA Technical Reports Server (NTRS)

    Brecht, Amanda S.; Hollingsworth, J. L.; Kahre, M. A.; Schaeffer, J. R.

    2012-01-01

    Extending the NASA Ames Mars General Circulation Model (MGCM) upper boundary will expand our understanding of the connection between the lower and upper atmosphere of Mars through the middle atmosphere. The extension's main requirements is incorporation of Non-local thermodynamic equilibrium (NLTE) heating (visible) and cooling (infrared). NLTE occurs when energy is exchanged more rapidly with the radiation field (or other energy sources) rather than collisions with other molecules. Without NLTE above approximately 80km/approximately 60km in Mars' atmosphere the IR/visible heating rates are overestimated. Currently NLTE has been applied successfully into the 1D RT code and is in progress for the 3D application.

  6. Europeana and 3D

    NASA Astrophysics Data System (ADS)

    Pletinckx, D.

    2011-09-01

    The current 3D hype creates a lot of interest in 3D. People go to 3D movies, but are we ready to use 3D in our homes, in our offices, in our communication? Are we ready to deliver real 3D to a general public and use interactive 3D in a meaningful way to enjoy, learn, communicate? The CARARE project is realising this for the moment in the domain of monuments and archaeology, so that real 3D of archaeological sites and European monuments will be available to the general public by 2012. There are several aspects to this endeavour. First of all is the technical aspect of flawlessly delivering 3D content over all platforms and operating systems, without installing software. We have currently a working solution in PDF, but HTML5 will probably be the future. Secondly, there is still little knowledge on how to create 3D learning objects, 3D tourist information or 3D scholarly communication. We are still in a prototype phase when it comes to integrate 3D objects in physical or virtual museums. Nevertheless, Europeana has a tremendous potential as a multi-facetted virtual museum. Finally, 3D has a large potential to act as a hub of information, linking to related 2D imagery, texts, video, sound. We describe how to create such rich, explorable 3D objects that can be used intuitively by the generic Europeana user and what metadata is needed to support the semantic linking.

  7. Constraints on the Lost City Hydrothermal System from borehole thermal data; 3-D models of heat flow and hydrothermal circulation in an oceanic core complex.

    NASA Astrophysics Data System (ADS)

    Titarenko, S.; McCaig, A. M.

    2014-12-01

    A perennial problem in near-ridge hydrothermal circulation is that the only directly measurable data to test models is often vent fluid temperature. Surface heat flow measurements may be available but without the underlying thermal structure it is not known if they are transient and affected by local hydrothermal flow, or conductive. The Atlantis Massif oceanic core complex at 30 °N on the mid-Atlantic Ridge, offers a unique opportunity to better constrain hydrothermal circulation models. The temperature profile in gabbroic rocks of IODP Hole 1309D was measured in IODPExpedition 340T, and found to be near-conductive, but with a slight inflexion at ~750 mbsf indicating downward advection of fluid above that level. The lack of deep convection is especially remarkable given that the long-lived Lost City Hydrothermal Field (LCHF) is located only 5km to the south. We have modelled hydrothermal circulation in the Massif using Comsol Multiphysics, comparing 2-D and 3-D topographic models and using temperature-dependent conductivity to give the best estimate of heatflow into the Massif. We can constrain maximum permeability in gabbro below 750 mbsf to 5e-17 m2. The thermal gradient in the upper part of the borehole can be matched with a permeability of 3e-14 m2 in a 750 m thick layer parallel to the surface of the massif, with upflow occurring in areas of high topography and downflow at the location of the borehole. However in 3-D the precise flow pattern is quite model dependent, and the thermal structure can be matched either by downflow centred on the borehole at lower permeability or centred a few hundred metres from the borehole at higher permeability. The borehole gradient is compatible with the longevity (>120 kyr) and outflow temperature (40-90 °C) of the LCHF either with a deep more permeable (1e-14 m2 to 1e-15 m2) domain beneath the vent site in 2-D or a permeable fault slot 500 to 1000m wide and parallel to the transform fault in 3-D. In both cases topography

  8. A general circulation model (GCM) parameterization of Pinatubo aerosols

    SciTech Connect

    Lacis, A.A.; Carlson, B.E.; Mishchenko, M.I.

    1996-04-01

    The June 1991 volcanic eruption of Mt. Pinatubo is the largest and best documented global climate forcing experiment in recorded history. The time development and geographical dispersion of the aerosol has been closely monitored and sampled. Based on preliminary estimates of the Pinatubo aerosol loading, general circulation model predictions of the impact on global climate have been made.

  9. Calibrating the ECCO ocean general circulation model using Green's functions

    NASA Technical Reports Server (NTRS)

    Menemenlis, D.; Fu, L. L.; Lee, T.; Fukumori, I.

    2002-01-01

    Green's functions provide a simple, yet effective, method to test and calibrate General-Circulation-Model(GCM) parameterizations, to study and quantify model and data errors, to correct model biases and trends, and to blend estimates from different solutions and data products.

  10. Feasibility study: Atmospheric general circulation experiment, volume 2

    NASA Technical Reports Server (NTRS)

    Homsey, R. J. (Editor)

    1981-01-01

    The feasibility analysis of the atmospheric general circulation experiment (AGCE) are documented. The analysis performed in each technical area, the rationale and substantiation for the design approaches selected for the hardware, and the design details for the baseline AGCE are presented.

  11. Improving the management of multimorbidity in general practice: protocol of a cluster randomised controlled trial (The 3D Study)

    PubMed Central

    Chaplin, Katherine; Bower, Peter; Brookes, Sara; Fitzpatrick, Bridie; Guthrie, Bruce; Shaw, Alison; Mercer, Stewart; Rafi, Imran; Thorn, Joanna

    2016-01-01

    Introduction An increasing number of people are living with multimorbidity. The evidence base for how best to manage these patients is weak. Current clinical guidelines generally focus on single conditions, which may not reflect the needs of patients with multimorbidity. The aim of the 3D study is to develop, implement and evaluate an intervention to improve the management of patients with multimorbidity in general practice. Methods and analysis This is a pragmatic two-arm cluster randomised controlled trial. 32 general practices around Bristol, Greater Manchester and Glasgow will be randomised to receive either the ‘3D intervention’ or usual care. 3D is a complex intervention including components affecting practice organisation, the conduct of patient reviews, integration with secondary care and measures to promote change in practice organisation. Changes include improving continuity of care and replacing reviews of each disease with patient-centred reviews with a focus on patients' quality of life, mental health and polypharmacy. We aim to recruit 1383 patients who have 3 or more chronic conditions. This provides 90% power at 5% significance level to detect an effect size of 0.27 SDs in the primary outcome, which is health-related quality of life at 15 months using the EQ-5D-5L. Secondary outcome measures assess patient centredness, illness burden and treatment burden. The primary analysis will be a multilevel regression model adjusted for baseline, stratification/minimisation, clustering and important co-variables. Nested process evaluation will assess implementation, mechanisms of effectiveness and interaction of the intervention with local context. Economic analysis of cost-consequences and cost-effectiveness will be based on quality-adjusted life years. Ethics and dissemination This study has approval from South-West (Frenchay) National Health Service (NHS) Research Ethics Committee (14/SW/0011). Findings will be disseminated via final report, peer

  12. Full 3D dispersion curve solutions for guided waves in generally anisotropic media

    NASA Astrophysics Data System (ADS)

    Hernando Quintanilla, F.; Lowe, M. J. S.; Craster, R. V.

    2016-02-01

    Dispersion curves of guided waves provide valuable information about the physical and elastic properties of waves propagating within a given waveguide structure. Algorithms to accurately compute these curves are an essential tool for engineers working in non-destructive evaluation and for scientists studying wave phenomena. Dispersion curves are typically computed for low or zero attenuation and presented in two or three dimensional plots. The former do not always provide a clear and complete picture of the dispersion loci and the latter are very difficult to obtain when high values of attenuation are involved and arbitrary anisotropy is considered in single or multi-layered systems. As a consequence, drawing correct and reliable conclusions is a challenging task in the modern applications that often utilize multi-layered anisotropic viscoelastic materials. These challenges are overcome here by using a spectral collocation method (SCM) to robustly find dispersion curves in the most complicated cases of high attenuation and arbitrary anisotropy. Solutions are then plotted in three-dimensional frequency-complex wavenumber space, thus gaining much deeper insight into the nature of these problems. The cases studied range from classical examples, which validate this approach, to new ones involving materials up to the most general triclinic class for both flat and cylindrical geometry in multi-layered systems. The apparent crossing of modes within the same symmetry family in viscoelastic media is also explained and clarified by the results. Finally, the consequences of the centre of symmetry, present in every crystal class, on the solutions are discussed.

  13. A 3D graphene oxide microchip and a Au-enwrapped silica nanocomposite-based supersandwich cytosensor toward capture and analysis of circulating tumor cells

    NASA Astrophysics Data System (ADS)

    Li, Na; Xiao, Tingyu; Zhang, Zhengtao; He, Rongxiang; Wen, Dan; Cao, Yiping; Zhang, Weiying; Chen, Yong

    2015-10-01

    Determination of the presence and number of circulating tumor cells (CTCs) in peripheral blood can provide clinically important data for prognosis and therapeutic response patterns. In this study, a versatile supersandwich cytosensor was successfully developed for the highly sensitive and selective analysis of CTCs using Au-enwrapped silica nanocomposites (Si/AuNPs) and three-dimensional (3D) microchips. First, 3D microchips were fabricated by a photolithography method. Then, the prepared substrate was applied to bind graphene oxide, streptavidin and biotinylated epithelial-cell adhesion-molecule antibody, resulting in high stability, bioactivity, and capability for CTCs capture. Furthermore, horseradish peroxidase and anti-CA153 were co-linked to the Si/AuNPs for signal amplification. The performance of the cytosensor was evaluated with MCF7 breast cancer cells. Under optimal conditions, the proposed supersandwich cytosensor showed high sensitivity with a wide range of 101 to 107 cells per mL and a detection limit of 10 cells per mL. More importantly, it could effectively distinguish CTCs from normal cells, which indicated the promising applications of our method for the clinical diagnosis and therapeutic monitoring of cancers.

  14. A generalized approach for historical mock-up acquisition and data modelling: Towards historically enriched 3D city models

    NASA Astrophysics Data System (ADS)

    Hervy, B.; Billen, R.; Laroche, F.; Carré, C.; Servières, M.; Van Ruymbeke, M.; Tourre, V.; Delfosse, V.; Kerouanton, J.-L.

    2012-10-01

    Museums are filled with hidden secrets. One of those secrets lies behind historical mock-ups whose signification goes far behind a simple representation of a city. We face the challenge of designing, storing and showing knowledge related to these mock-ups in order to explain their historical value. Over the last few years, several mock-up digitalisation projects have been realised. Two of them, Nantes 1900 and Virtual Leodium, propose innovative approaches that present a lot of similarities. This paper presents a framework to go one step further by analysing their data modelling processes and extracting what could be a generalized approach to build a numerical mock-up and the knowledge database associated. Geometry modelling and knowledge modelling influence each other and are conducted in a parallel process. Our generalized approach describes a global overview of what can be a data modelling process. Our next goal is obviously to apply this global approach on other historical mock-up, but we also think about applying it to other 3D objects that need to embed semantic data, and approaching historically enriched 3D city models.

  15. Effects of cumulus convection on the simulated monsoon circulation in a general circulation model

    SciTech Connect

    Zhang, Guang Jun )

    1994-09-01

    The effect of cumulus convection on the Asian summer monsoon circulation is investigated, using a general circulation model. Two simulations for the summer months (June, July, and August) are performed, one parameterizing convection using a mass flux scheme and the other without convective parameterization. The results show that convection has significant effects on the monsoon circulation and its associated precipitation. In the simulation with the mass flux convective parameterization, precipitation in the western Pacific is decreased, together with a decrease in surface evaporation and wind speed. In the indian monsoon region it is almost the opposite. Comparison with a simulation using moist convective adjustment to parameterize convection shows that the monsoon circulation and precipitation distribution in the no-convection simulation are very similar to those in the simulation with moist convective adjustment. The difference in the large-scale circulation with and without convective parameterization is interpreted in terms of convective stabilization of the atmosphere by convection, using dry and moist static energy budgets. It is shown that weakening of the low-level convergence in the western Pacific in the simulation with convection is closely associated with the stabilization of the atmosphere by convection, mostly through drying of the lower troposphere; changes in low-level convergence lead to changes in precipitation. The precipitation increase in the Indian monsoon can be explained similarly. 29 refs., 12 figs.

  16. Efficient and robust 3D CT image reconstruction based on total generalized variation regularization using the alternating direction method.

    PubMed

    Chen, Jianlin; Wang, Linyuan; Yan, Bin; Zhang, Hanming; Cheng, Genyang

    2015-01-01

    Iterative reconstruction algorithms for computed tomography (CT) through total variation regularization based on piecewise constant assumption can produce accurate, robust, and stable results. Nonetheless, this approach is often subject to staircase artefacts and the loss of fine details. To overcome these shortcomings, we introduce a family of novel image regularization penalties called total generalized variation (TGV) for the effective production of high-quality images from incomplete or noisy projection data for 3D reconstruction. We propose a new, fast alternating direction minimization algorithm to solve CT image reconstruction problems through TGV regularization. Based on the theory of sparse-view image reconstruction and the framework of augmented Lagrange function method, the TGV regularization term has been introduced in the computed tomography and is transformed into three independent variables of the optimization problem by introducing auxiliary variables. This new algorithm applies a local linearization and proximity technique to make the FFT-based calculation of the analytical solutions in the frequency domain feasible, thereby significantly reducing the complexity of the algorithm. Experiments with various 3D datasets corresponding to incomplete projection data demonstrate the advantage of our proposed algorithm in terms of preserving fine details and overcoming the staircase effect. The computation cost also suggests that the proposed algorithm is applicable to and is effective for CBCT imaging. Theoretical and technical optimization should be investigated carefully in terms of both computation efficiency and high resolution of this algorithm in application-oriented research.

  17. The Stagger-grid: A grid of 3D stellar atmosphere models. I. Methods and general properties

    NASA Astrophysics Data System (ADS)

    Magic, Z.; Collet, R.; Asplund, M.; Trampedach, R.; Hayek, W.; Chiavassa, A.; Stein, R. F.; Nordlund, Å.

    2013-09-01

    Aims: We present the Stagger-grid, a comprehensive grid of time-dependent, three-dimensional (3D), hydrodynamic model atmospheres for late-type stars with realistic treatment of radiative transfer, covering a wide range in stellar parameters. This grid of 3D models is intended for various applications besides studies of stellar convection and atmospheres per se, including stellar parameter determination, stellar spectroscopy and abundance analysis, asteroseismology, calibration of stellar evolution models, interferometry, and extrasolar planet search. In this introductory paper, we describe the methods we applied for the computation of the grid and discuss the general properties of the 3D models as well as of their temporal and spatial averages (here denoted ⟨3D⟩ models). Methods: All our models were generated with the Stagger-code, using realistic input physics for the equation of state (EOS) and for continuous and line opacities. Our ~ 220 grid models range in effective temperature, Teff, from 4000 to 7000 K in steps of 500 K, in surface gravity, log g, from 1.5 to 5.0 in steps of 0.5 dex, and metallicity, [Fe/H], from - 4.0 to + 0.5 in steps of 0.5 and 1.0 dex. Results: We find a tight scaling relation between the vertical velocity and the surface entropy jump, which itself correlates with the constant entropy value of the adiabatic convection zone. The range in intensity contrast is enhanced at lower metallicity. The granule size correlates closely with the pressure scale height sampled at the depth of maximum velocity. We compare the ⟨3D⟩ models with currently widely applied one-dimensional (1D) atmosphere models, as well as with theoretical 1D hydrostatic models generated with the same EOS and opacity tables as the 3D models, in order to isolate the effects of using self-consistent and hydrodynamic modeling of convection, rather than the classical mixing length theory approach. For the first time, we are able to quantify systematically over a broad

  18. Adaptation of a general circulation model to ocean dynamics

    NASA Technical Reports Server (NTRS)

    Turner, R. E.; Rees, T. H.; Woodbury, G. E.

    1976-01-01

    A primitive-variable general circulation model of the ocean was formulated in which fast external gravity waves are suppressed with rigid-lid surface constraint pressires which also provide a means for simulating the effects of large-scale free-surface topography. The surface pressure method is simpler to apply than the conventional stream function models, and the resulting model can be applied to both global ocean and limited region situations. Strengths and weaknesses of the model are also presented.

  19. Treatment of cloud radiative effects in general circulation models

    SciTech Connect

    Wang, W.C.; Dudek, M.P.; Liang, X.Z.; Ding, M.

    1996-04-01

    We participate in the Atmospheric Radiation Measurement (ARM) program with two objectives: (1) to improve the general circulation model (GCM) cloud/radiation treatment with a focus on cloud verticle overlapping and layer cloud optical properties, and (2) to study the effects of cloud/radiation-climate interaction on GCM climate simulations. This report summarizes the project progress since the Fourth ARM Science Team meeting February 28-March 4, 1994, in Charleston, South Carolina.

  20. Asian Summer Monsoon Intraseasonal Variability in General Circulation Models

    SciTech Connect

    Sperber, K R; Annamalai, H

    2004-02-24

    The goals of this report are: (1) Analyze boreal summer Asian monsoon intraseasonal variability general circulation models--How well do the models represent the eastward and northward propagating components of the convection and how well do the models represent the interactive control that the western tropical Pacific rainfall exerts on the rainfall over India and vice-versa? (2) Role of air-sea interactions--prescribed vs. interactive ocean; and (3) Mean monsoon vs. variability.

  1. Cloud Feedback in Atmospheric General Circulation Models: An Update

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Zhang, M. H.; Ingram, W. J.; Potter, G. L.; Alekseev, V.; Barker, H. W.; Cohen-Solal, E.; Colman, R. A.; Dazlich, D. A.; DelGenio, A. D.; Dix, M. R.; Dymnikov, V.; Esch, M.; Fowler, L. D.; Fraser, J. R.; Galin, V.; Gates, W. L.; Hack, J. J.; Kiehl, J. T.; LeTreut, H.

    1996-01-01

    Six years ago, we compared the climate sensitivity of 19 atmospheric general circulation models and found a roughly threefold variation among the models; most of this variation was attributed to differences in the models' depictions of cloud feedback. In an update of this comparison, current models showed considerably smaller differences in net cloud feedback, with most producing modest values. There are, however, substantial differences in the feedback components, indicating that the models still have physical disagreements.

  2. Baroclinic Rossby Wave Signature in a General Circulation Ocean Model.

    DTIC Science & Technology

    1983-06-01

    northwest with a wavelength cf 300 km. For other laritudes of the North acific Ocean , Price and Maqaard (1980) determined that first mode baroclinic Rossby...role in the latitude belt 40-50N in the North acific 10 -. - !o Ocean . Magaard (1983) ir. a paper discussing bariclin _c Rossty wave energetics...HD-AI132 219 BAROCLINIC ROSSBY WAVE SIGNATURE IN A GENERAL CIRCULATION OCEAN MODEL(U) NAVAL POSTGRADUATE SCHOOLU MONTEREY CA A H RUTSCH JUN 83

  3. Anisotropic Mesoscale Eddy Transport in Ocean General Circulation Models

    NASA Astrophysics Data System (ADS)

    Reckinger, S. J.; Fox-Kemper, B.; Bachman, S.; Bryan, F.; Dennis, J.; Danabasoglu, G.

    2014-12-01

    Modern climate models are limited to coarse-resolution representations of large-scale ocean circulation that rely on parameterizations for mesoscale eddies. The effects of eddies are typically introduced by relating subgrid eddy fluxes to the resolved gradients of buoyancy or other tracers, where the proportionality is, in general, governed by an eddy transport tensor. The symmetric part of the tensor, which represents the diffusive effects of mesoscale eddies, is universally treated isotropically in general circulation models. Thus, only a single parameter, namely the eddy diffusivity, is used at each spatial and temporal location to impart the influence of mesoscale eddies on the resolved flow. However, the diffusive processes that the parameterization approximates, such as shear dispersion, potential vorticity barriers, oceanic turbulence, and instabilities, typically have strongly anisotropic characteristics. Generalizing the eddy diffusivity tensor for anisotropy extends the number of parameters to three: a major diffusivity, a minor diffusivity, and the principal axis of alignment. The Community Earth System Model (CESM) with the anisotropic eddy parameterization is used to test various choices for the newly introduced parameters, which are motivated by observations and the eddy transport tensor diagnosed from high resolution simulations. Simply setting the ratio of major to minor diffusivities to a value of five globally, while aligning the major axis along the flow direction, improves biogeochemical tracer ventilation and reduces global temperature and salinity biases. These effects can be improved even further by parameterizing the anisotropic transport mechanisms in the ocean.

  4. Interactive data exploration and particle tracking for general circulation models

    NASA Technical Reports Server (NTRS)

    Rosenbaum, R. I.; Peskin, R. L.; Walther, S. S.; Zinn, H. P.

    1995-01-01

    The SCENE environment for interactive visualization of complex data sets is discussed. This environment is used to create tools for graphical exploration of atmospheric flow models. These tools may be extended by the user in a seamless manner, so that no programming is required. A module for accurately tracing field lines and particle trajectories in SCENE is presented. This is used to examine the flowfield qualitatively with streamlines and pathlines and to identify critical points in the velocity field. The paper also describes a visualization tool for general circulation models on which the primary features of the environment are demonstrated.

  5. Tropical disturbances in relation to general circulation modeling

    NASA Technical Reports Server (NTRS)

    Estoque, M. A.

    1982-01-01

    The initial results of an evaluation of the performance of the Goddard Laboratory of Atmospheric Simulation general circulation model depicting the tropical atmosphere during the summer are presented. Because the results show the existence of tropical wave disturbances throughout the tropics, the characteristics of synoptic disturbances over Africa were studied and a synoptic case study of a selected disturbance in this area was conducted. It is shown that the model is able to reproduce wave type synoptic disturbances in the tropics. The findings show that, in one of the summers simulated, the disturbances are predominantly closed vortices; in another summer, the predominant disturbances are open waves.

  6. A theoretical study of the efficiency of the general circulation

    NASA Technical Reports Server (NTRS)

    Schulman, L. L.

    1977-01-01

    The paper examines the problem of explaining the atmospheric efficiency, or equivalently, the rate of generation of available potential energy (APE) by diabatic heating. Attention is focused on determining the maximum possible rate of generation of APE and its accompanying temperature field, which does not require a knowledge of the atmospheric motions leading to temperature distribution. Qualitative and quantitative results indicate that the atmosphere may be operating within approximately a factor of 2 of its maximum efficiency. The general circulation may be operating at nearly its maximum efficiency.

  7. A Moist Idealized Test Case for Atmospheric General Circulation Models

    NASA Astrophysics Data System (ADS)

    Thatcher, D.; Jablonowski, C.; Zarzycki, C.

    2013-12-01

    The vast array of dynamical and physical processes within atmospheric general circulation models (GCMs) makes it difficult to correctly distinguish the sources of error within a model. Therefore, simplified test cases are important in testing the accuracy of individual model components, such as the fluid flow component in the dynamical core. Typically, dynamical cores are coupled to complex subgrid-scale physical parameterization packages, and the nonlinear interactions mask the causes and effects of atmospheric phenomena. Idealized tests are a computationally efficient method for analyzing the underlying numerical techniques of dynamical cores. The newly proposed test case is based on the widely-used Held and Suarez (1994) (HS) test for dry dynamical cores. The latter replaces the full physical parameterization package with a Newtonian temperature relaxation and Rayleigh damping of low-level winds on a flat planet. However, the impact of moisture, a crucial physics-dynamics coupling process, is missing from the HS test. Here we present a moist variant of the HS test case to create a test case of intermediate complexity with idealized moisture feedbacks. It uses simplified physical processes to model large-scale condensation, boundary layer turbulence, and surface fluxes of horizontal momentum, latent heat, and sensible heat between the atmosphere and an ocean-covered planet (Reed and Jablonowski, 2012). We apply this test to four dynamical cores within NCAR's Community Atmosphere Model version 5.3, including the Finite Volume, Eulerian spectral transform, semi-Lagrangian spectral transform, and Spectral Element dynamical cores. We analyze the kinetic energy spectra, general circulation, and precipitation of this new moist idealized test case across all four dynamical cores. Simulations of the moist idealized test case are compared to aqua-planet experiments with complex physical parameterizations. The moist idealized test case successfully reproduces many features

  8. Interactions Between the Thermohaline Circulation and Tropical Atlantic SST in a Coupled General Circulation Model

    NASA Technical Reports Server (NTRS)

    Miller, Ron; Jiang, Xing-Jian; Travis, Larry (Technical Monitor)

    2001-01-01

    Tropical Atlantic SST shows a (statistically well-defined) decadal time scale in a 104-year simulation of unforced variability by a coupled general circulation model (CGCM). The SST anomalies superficially resemble observed Tropical Atlantic variability (TAV), and are associated with changes in the atmospheric circulation. Brazilian rainfall is modulated with a decadal time scale, along with the strength of the Atlantic trade winds, which are associated with variations in evaporation and the net surface heat flux. However, in contrast to observed tropical Atlantic variability, the trade winds damp the associated anomalies in ocean temperature, indicating a negative feedback. Tropical SST anomalies in the CGCM, though opposed by the surface heat flux, are advected in from the Southern Hemisphere mid-latitudes. These variations modulate the strength of the thermohaline circulation (THC): warm, salty anomalies at the equator sink drawing cold, fresh mid-latitude water. Upon reaching the equator, the latter inhibit vertical overturning and advection from higher latitudes, which allows warm, salty anomalies to reform, returning the cycle to its original state. Thus, the cycle results from advection of density anomalies and the effect of these anomalies upon the rate of vertical overturning and surface advection. This decadal modulation of Tropical Atlantic SST and the thermohaline circulation is correlated with ocean heat transport to the Northern Hemisphere high latitudes and Norwegian Sea SST. Because of the central role of equatorial convection, we question whether this mechanism is present in the current climate, although we speculate that it may have operated in palaeo times, depending upon the stability of the tropical water column.

  9. Development and Implementation of 3-D, High Speed Capacitance Tomography for Imaging Large-Scale, Cold-Flow Circulating Fluidized Bed

    SciTech Connect

    Marashdeh, Qussai

    2013-02-01

    A detailed understanding of multiphase flow behavior inside a Circulating Fluidized Bed (CFB) requires a 3-D technique capable of visualizing the flow field in real-time. Electrical Capacitance Volume Tomography (ECVT) is a newly developed technique that can provide such measurements. The attractiveness of the technique is in its low profile sensors, fast imaging speed and scalability to different section sizes, low operating cost, and safety. Moreover, the flexibility of ECVT sensors enable them to be designed around virtually any geometry, rendering them suitable to be used for measurement of solid flows in exit regions of the CFB. Tech4Imaging LLC has worked under contract with the U.S. Department of Energy's National Energy Technology Laboratory (DOE NETL) to develop an ECVT system for cold flow visualization and install it on a 12 inch ID circulating fluidized bed. The objective of this project was to help advance multi-phase flow science through implementation of an ECVT system on a cold flow model at DOE NETL. This project has responded to multi-phase community and industry needs of developing a tool that can be used to develop flow models, validate computational fluid dynamics simulations, provide detailed real-time feedback of process variables, and provide a comprehensive understating of multi-phase flow behavior. In this project, a complete ECVT system was successfully developed after considering different potential electronics and sensor designs. The system was tested at various flow conditions and with different materials, yielding real-time images of flow interaction in a gas-solid flow system. The system was installed on a 12 inch ID CFB of the US Department of Energy, Morgantown Labs. Technical and economic assessment of Scale-up and Commercialization of ECVT was also conducted. Experiments conducted with larger sensors in conditions similar to industrial settings are very promising. ECVT has also the potential to be developed for imaging multi

  10. Integrated and spectral energetics of the GLAS general circulation model

    NASA Technical Reports Server (NTRS)

    Tenenbaum, J.

    1982-01-01

    Integrated and spectral error energetics of the GLAS General circulation model are compared with observations for periods in January 1975, 1976, and 1977. For two cases the model shows significant skill in predicting integrated energetics quantities out to two weeks, and for all three cases, the integrated monthly mean energetics show qualitative improvements over previous versions of the model in eddy kinetic energy and barotropic conversions. Fundamental difficulties remain with leakage of energy to the stratospheric level, particularly above strong initial jet streams associated in part with regions of steep terrain. The spectral error growth study represents the first comparison of general circulation model spectral energetics predictions with the corresponding observational spectra on a day by day basis. The major conclusion is that eddy kinetics energy can be correct while significant errors occur in the kinetic energy of wavenumber 3. Both the model and observations show evidence of single wavenumber dominance in eddy kinetic energy and the correlation of spectral kinetics and potential energy.

  11. A parallel coupled oceanic-atmospheric general circulation model

    SciTech Connect

    Wehner, M.F.; Bourgeois, A.J.; Eltgroth, P.G.; Duffy, P.B.; Dannevik, W.P.

    1994-12-01

    The Climate Systems Modeling group at LLNL has developed a portable coupled oceanic-atmospheric general circulation model suitable for use on a variety of massively parallel (MPP) computers of the multiple instruction, multiple data (MIMD) class. The model is composed of parallel versions of the UCLA atmospheric general circulation model, the GFDL modular ocean model (MOM) and a dynamic sea ice model based on the Hiber formulation extracted from the OPYC ocean model. The strategy to achieve parallelism is twofold. One level of parallelism is accomplished by applying two dimensional domain decomposition techniques to each of the three constituent submodels. A second level of parallelism is attained by a concurrent execution of AGCM and OGCM/sea ice components on separate sets of processors. For this functional decomposition scheme, a flux coupling module has been written to calculate the heat, moisture and momentum fluxes independent of either the AGCM or the OGCM modules. The flux coupler`s other roles are to facilitate the transfer of data between subsystem components and processors via message passing techniques and to interpolate and aggregate between the possibly incommensurate meshes.

  12. Net diffusivity in ocean general circulation models with nonuniform grids

    NASA Technical Reports Server (NTRS)

    Yin, F. L.; Fung, I. Y.

    1991-01-01

    The numerical vertical diffusivity K(num), embedded in a numerical ocean general circulation model with nonuniform vertical grid, is estimated. It is shown that in a downwelling region, K(num) is negative for a grid with grid size increasing with depth. When the grid size increment, or the downward vertical velocity, is large, K(num) may exceed the vertical diffusivity specified and may result in a negative effective vertical diffusivity. Therefore care needs to be taken to specify the vertical diffusivity in a numerical model with nonuniform grid, and a lower bound is generally imposed in order to avoid an unphysical negative value. Some possible effects of the negative effective diffusivity are discussed.

  13. A Pacific Ocean general circulation model for satellite data assimilation

    NASA Technical Reports Server (NTRS)

    Chao, Y.; Halpern, D.; Mechoso, C. R.

    1991-01-01

    A tropical Pacific Ocean General Circulation Model (OGCM) to be used in satellite data assimilation studies is described. The transfer of the OGCM from a CYBER-205 at NOAA's Geophysical Fluid Dynamics Laboratory to a CRAY-2 at NASA's Ames Research Center is documented. Two 3-year model integrations from identical initial conditions but performed on those two computers are compared. The model simulations are very similar to each other, as expected, but the simulations performed with the higher-precision CRAY-2 is smoother than that with the lower-precision CYBER-205. The CYBER-205 and CRAY-2 use 32 and 64-bit mantissa arithmetic, respectively. The major features of the oceanic circulation in the tropical Pacific, namely the North Equatorial Current, the North Equatorial Countercurrent, the South Equatorial Current, and the Equatorial Undercurrent, are realistically produced and their seasonal cycles are described. The OGCM provides a powerful tool for study of tropical oceans and for the assimilation of satellite altimetry data.

  14. Associations Between South African Rainfall and The General Circulation

    NASA Astrophysics Data System (ADS)

    Tennant, W. J.

    The atmospheric energy cycle, as described by Lorenz, is fundamental to weather and climate. However, the question is how much of the climatic variability can be ascribed to fluctuations in the energy cycle. This study shows that there are indeed strong associations between summer rainfall in central and northern South Africa and the global energy cycle. These associations are manifest through fluctuations in the tropical Hadley circulations, that affect the baroclinicity of the mid-latitudes, that in turn force tropical and sub-tropical circulations. Twice-daily fields from the NCEP/NCAR reanalysis data are used to calculate at- mospheric available potential and kinetic energy and the conversions between these energy forms for mean and eddy components in time and space. Self-organizing maps (SOMs) are used to determine dominant modes within these atmospheric data. The rel- ative frequency of these modes are then assessed for periods of different rainfall char- acteristics. These include, among others, wet and dry seasons and the spatial spread of rainfall. These associations provide insight into the causes of rainfall variability in the African region and open new possibilities in the field of seasonal prediction. If General Circu- lation Models (GCMs) are able to capture fluctuations in the global energy cycle accu- rately, which does seem likely given some preliminary results, more accurate seasonal forecasts may be attempted. This despite the GCMs having difficulty in simulating the smaller-scale motion and associated non-linear interaction.

  15. Exploring the Venus global super-rotation using a comprehensive general circulation model

    NASA Astrophysics Data System (ADS)

    Mendonça, J. M.; Read, P. L.

    2016-12-01

    The atmospheric circulation in Venus is well known to exhibit strong super-rotation. However, the atmospheric mechanisms responsible for the formation of this super-rotation are still not fully understood. In this work, we developed a new Venus general circulation model to study the most likely mechanisms driving the atmosphere to the current observed circulation. Our model includes a new radiative transfer, convection and suitably adapted boundary layer schemes and a dynamical core that takes into account the dependence of the heat capacity at constant pressure with temperature. The new Venus model is able to simulate a super-rotation phenomenon in the cloud region quantitatively similar to the one observed. The mechanisms maintaining the strong winds in the cloud region were found in the model results to be a combination of zonal mean circulation, thermal tides and transient waves. In this process, the semi-diurnal tide excited in the upper clouds has a key contribution in transporting axial angular momentum mainly from the upper atmosphere towards the cloud region. The magnitude of the super-rotation in the cloud region is sensitive to various radiative parameters such as the amount of solar radiative energy absorbed by the surface, which controls the static stability near the surface. In this work, we also discuss the main difficulties in representing the flow below the cloud base in Venus atmospheric models. Our new radiative scheme is more suitable for 3D Venus climate models than those used in previous work due to its easy adaptability to different atmospheric conditions. This flexibility of the model was crucial to explore the uncertainties in the lower atmospheric conditions and may also be used in the future to explore, for example, dynamical-radiative-microphysical feedbacks.

  16. Relations between winter precipitation and atmospheric circulation simulated by the Geophysical Fluid Dynamics Laboratory general circulation model

    USGS Publications Warehouse

    McCabe, G.J.; Dettinger, M.D.

    1995-01-01

    General circulation model (GCM) simulations of atmospheric circulation are more reliable than GCM simulations of temperature and precipitation. In this study, temporal correlations between 700 hPa height anomalies simulated winter precipitation at eight locations in the conterminous United States are compared with corresponding correlations in observations. The objectives are to 1) characterize the relations between atmospheric circulation and winter precipitation simulated by the GFDL, GCM for selected locations in the conterminous USA, ii) determine whether these relations are similar to those found in observations of the actual climate system, and iii) determine if GFDL-simulated precipitation is forced by the same circulation patterns as in the real atmosphere. -from Authors

  17. Development of a hybrid cloud parameterization for general circulation models

    SciTech Connect

    Kao, C.Y.J.; Kristjansson, J.E.; Langley, D.L.

    1995-04-01

    We have developed a cloud package with state-of-the-art physical schemes that can parameterize low-level stratus or stratocumulus, penetrative cumulus, and high-level cirrus. Such parameterizations will improve cloud simulations in general circulation models (GCMs). The principal tool in this development comprises the physically based Arakawa-Schubert scheme for convective clouds and the Sundqvist scheme for layered, nonconvective clouds. The term {open_quotes}hybrid{close_quotes} addresses the fact that the generation of high-attitude layered clouds can be associated with preexisting convective clouds. Overall, the cloud parameterization package developed should better determine cloud heating and drying effects in the thermodynamic budget, realistic precipitation patterns, cloud coverage and liquid/ice water content for radiation purposes, and the cloud-induced transport and turbulent diffusion for atmospheric trace gases.

  18. Extending the NASA Ames Mars General Circulation Model to Explore Mars’ Middle Atmosphere

    NASA Astrophysics Data System (ADS)

    Brecht, Amanda; Hollingsworth, J.; Kahre, M.; Schaeffer, J.

    2013-10-01

    The NASA Ames Mars General Circulation Model (MGCM) upper boundary has been extended to ~120 km altitude (p ~10-5 mbar). The extension of the MGCM upper boundary initiates the ability to understand the connection between the lower and upper atmosphere of Mars through the middle atmosphere 70 - 120 km). Moreover, it provides the opportunity to support future missions (i.e. the 2013 MAVEN mission). A major factor in this extension is the incorporation of the Non-Local Thermodynamic Equilibrium (NLTE) heating (visible) and cooling (infrared). This modification to the radiative transfer forcing (i.e., RT code) has been significantly tested in a 1D vertical column and now has been ported to the full 3D Mars GCM. Initial results clearly show the effects of NLTE in the upper middle atmosphere. Diagnostic of seasonal mean fields and large-scale wave activity will be shown with insight into circulation patterns in the middle atmosphere. Furthermore, sensitivity tests with the resolution of the pressure and temperature grids, in which the k-coefficients are calculated upon, have been performed in the 1D RT code. Our progress on this research will be presented. Brecht is supported by NASA’s Postdoctoral Program at the Ames Research Center, administered by Oak Ridge Associated Universities through a contract with NASA.

  19. Exploring Mars' Middle Atmosphere with the Extended NASA Ames Mars General Circulation Model

    NASA Astrophysics Data System (ADS)

    Brecht, A. S.; Hollingsworth, J. L.; Kahre, M. A.; Schaeffer, J.

    2013-12-01

    The NASA Ames Mars General Circulation Model (Mars GCM) upper boundary has been extended to ~120 km altitude (pT ~ 10-6 mbar). The extension of the Mars GCM upper boundary initiates the ability to understand the connection between the lower and upper atmosphere of Mars through the middle atmosphere. Moreover, it provides the opportunity to support missions (i.e. the 2013 MAVEN mission). A major factor in this extension is the incorporation of the Non-Local Thermodynamic Equilibrium (NLTE) heating (visible) and cooling (infrared). The calculated solar heating rates (LTE heating rates) within the Mars GCM are corrected for NLTE by applying factors from Table 1 in López-Valverde et al. (1998). The CO2 15-μm cooling parameterizations is adapted from Bougher et al. (2006). This modification to the radiative transfer forcing has been significantly tested in a 1D vertical column (i.e. RT code) and now has been ported to the full 3D Mars GCM. Initial results clearly show the effects of NLTE in the upper middle atmosphere. Diagnostic of seasonal mean fields and large-scale wave activity will be shown with insight into circulation patterns in the middle atmosphere. Furthermore, sensitivity tests with the resolution of the pressure and temperature grids, in which the k-coefficients are calculated upon, have been performed in the 1D RT code. Our progress on this research will be presented.

  20. Venusian Polar Vortex reproduced by a general circulation model

    NASA Astrophysics Data System (ADS)

    Ando, Hiroki; Sugimoto, Norihiko; Takagi, Masahiro

    2016-10-01

    Unlike the polar vortices observed in the Earth, Mars and Titan atmospheres, the observed Venus polar vortex is warmer than the mid-latitudes at cloud-top levels (~65 km). This warm polar vortex is zonally surrounded by a cold latitude band located at ~60 degree latitude, which is a unique feature called 'cold collar' in the Venus atmosphere [e.g. Taylor et al. 1980; Piccioni et al. 2007]. Although these structures have been observed in numerous previous observations, the formation mechanism is still unknown. In addition, an axi-asymmetric feature is always seen in the warm polar vortex. It changes temporally and sometimes shows a hot polar dipole or S-shaped structure as shown by a lot of infrared measurements [e.g. Garate-Lopez et al. 2013; 2015]. However, its vertical structure has not been investigated. To solve these problems, we performed a numerical simulation of the Venus atmospheric circulation using a general circulation model named AFES for Venus [Sugimoto et al. 2014] and reproduced these puzzling features.And then, the reproduced structures of the atmosphere and the axi-asymmetirc feature are compared with some previous observational results.In addition, the quasi-periodical zonal-mean zonal wind fluctuation is also seen in the Venus polar vortex reproduced in our model. This might be able to explain some observational results [e.g. Luz et al. 2007] and implies that the polar vacillation might also occur in the Venus atmosphere, which is silimar to the Earth's polar atmosphere. We will also show some initial results about this point in this presentation.

  1. The Development of WARP - A Framework for Continuous Energy Monte Carlo Neutron Transport in General 3D Geometries on GPUs

    NASA Astrophysics Data System (ADS)

    Bergmann, Ryan

    general 3D geometries on GPUs, but compared to production codes like Serpent and MCNP, WARP has limited capabilities. Despite WARP's lack of features, its novel algorithm implementations show that high performance can be achieved on a GPU despite the inherently divergent program flow and sparse data access patterns. WARP is not ready for everyday nuclear reactor calculations, but is a good platform for further development of GPU-accelerated Monte Carlo neutron transport. In it's current state, it may be a useful tool for multiplication factor searches, i.e. determining reactivity coefficients by perturbing material densities or temperatures, since these types of calculations typically do not require many flux tallies. (Abstract shortened by UMI.)

  2. Modeling of Antarctic sea ice in a general circulation model

    SciTech Connect

    Wu, Xingren; Budd, W.F.; Simmonds, I.

    1997-04-01

    A dynamic-thermodynamic sea ice model is developed and coupled with the Melbourne University general circulation model to simulate the seasonal cycle of the Antarctic sea ice distributions The model is efficient, rapid to compute, and useful for a range of climate studies. The thermodynamic part of the sea ice model is similar to that developed by Parkinson and Washington, the dynamics contain a simplified ice rheology that resists compression. The thermodynamics is based on energy conservation at the top surface of the ice/snow, the ice/water interface, and the open water area to determine the ice formation, accretion, and ablation. A lead parameterization is introduced with an effective partitioning scheme for freezing between and under the ice floes. The dynamic calculation determines the motion of ice, which is forced with the atmospheric wind, taking account of ice resistance and rafting. The simulated sea ice distribution compares reasonably well with observations. The seasonal cycle of ice extent is well simulated in phase as well as in magnitude. Simulated sea ice thickness and concentration are also in good agreement with observations over most regions and serve to indicate the importance of advection and ocean drift in the determination of the sea ice distribution. 64 refs., 15 figs., 2 tabs.

  3. Correcting precipitation feature location in general circulation models

    NASA Astrophysics Data System (ADS)

    Levy, Adam A. L.; Jenkinson, Mark; Ingram, William; Allen, Myles

    2014-12-01

    There is much evidence that precipitation responses to global warming involve wet regions becoming wetter and dry regions drier. This presents challenges for the interpretation of projections from general circulation models (GCMs) which have substantial biases in the location of precipitation features. While improving GCM simulated precipitation is the most desirable solution, adaptation and mitigation decisions must be made with the models already available. Many techniques have been developed to correct biases in grid point precipitation intensities, but few have been introduced to correct for location biases. Here, we describe a new technique for correcting the spatial and seasonal location of climatological precipitation features. We design this technique to respect the geometry of the problem (spherical spatial dimensions, with cyclic seasons), while conserving either precipitation intensities, or integrated precipitation amount. We discuss the mathematical basis of the technique and investigate its behaviour in different regimes. We find that the resulting warps depend smoothly on the most influential parameter, which determines the balance between smoothness and closeness of fit. We show that the technique is capable of removing more than half the RMS error in a model's climatology, obtaining consistently better results when conserving integrated precipitation. To demonstrate the ability of the new technique to improve simulated precipitation changes, we apply our transformations to historical anomalies and show that RMS error is reduced relative to GPCP's anomalies by approximately 10% for both types of warp. This verifies that errors in precipitation changes can be reduced by correcting underlying location errors in a GCM's climatology.

  4. A Coupled General Circulation Model of the Archean Earth

    NASA Astrophysics Data System (ADS)

    Wolf, E. T.; Toon, O. B.

    2011-12-01

    We present results from a new coupled general circulation model suitable for deep paleoclimate studies. Particular interest is given to the faint young Sun paradox. The model is based on the Community Earth System Model maintained by the National Center for Atmospheric Research [1]. Prognostic atmosphere, ocean, land, ice, and hydrological cycle models are coupled. A new correlated-k radiative transfer model has been implemented allowing accurate flux calculations for anoxic atmospheres containing high concentrations of CO2 and CH4 [2, 3]. This model represents a significant improvement upon one-dimensional radiative-convective climate models used previously to study ancient climate [4]. Cloud and ice albedo feedbacks will be accurately quantified and new constraints on Archean surface temperatures will be revealed. References [1] Collins W.D. et al. "Description of the NCAR Community Atmosphere Model (CAM 3.0)." NCAR Technical Note, 2004. [2] Toon O.B., McKay, C.P., Ackerman, T.P. "Rapid Calculation of Radiative Heating Rates and Photodissociation Rates in Inhomogeneous Multiple Scattering Atmospheres." J. Geo. Res., 94(D13), 16287 - 16301, 1989. [3] Mlawer, E.J., et al. "Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave." J. Geo. Res., 102(D14), 16663 - 16682, 1997. [4] Kasting J.F., Pollack, J.B., Crisp, D. "Effects of High CO2 Levels on Surface Temperature and Atmospheric Oxidation State of the Early Earth." J. Atm. Chem., 1, 403-428, 1984.

  5. A bulk cloud parameterization in a Venus General Circulation Model

    NASA Astrophysics Data System (ADS)

    Lee, Christopher; Lewis, Stephen R.; Read, Peter L.

    2010-04-01

    A condensing cloud parameterization is included in a super-rotating Venus General Circulation Model. A parameterization including condensation, evaporation and sedimentation of mono-modal sulfuric acid cloud particles is described. Saturation vapor pressure of sulfuric acid vapor is used to determine cloud formation through instantaneous condensation and destruction through evaporation, while pressure dependent viscosity of a carbon dioxide atmosphere is used to determine sedimentation rates assuming particles fall at their terminal Stokes velocity. Modifications are described to account for the large range of the Reynolds number seen in the Venus atmosphere. Two GCM experiments initialized with 10 ppm-equivalent of sulfuric acid are integrated for 30 Earth years and the results are discussed with reference to "Y" shaped cloud structures observed on Venus. The GCM is able to produce an analog of the "Y" shaped cloud structure through dynamical processes alone, with contributions from the mean westward wind, the equatorial Kelvin wave, and the mid-latitude/polar Mixed Rossby/Gravity waves. The cloud top height in the GCM decreases from equator to pole and latitudinal gradients of cloud top height are comparable to those observed by Pioneer Venus and Venus Express, and those produced in more complex microphysical models of the sulfur cycle on Venus. Differences between the modeled cloud structures and observations are described and dynamical explanations are suggested for the most prominent differences.

  6. Feasibility study: Atmospheric general circulation experiment, volume 1

    NASA Technical Reports Server (NTRS)

    Homsey, R. J. (Editor)

    1981-01-01

    The atmospheric general circulation experiment (AGCE) uses a rotating fluid flow cell assembly. The key technical areas affecting the feasibility of the design and operation of the AGCE are investigated. The areas investigated include materials for the flow cell assembly, thermal design, high voltage power supply design, effective retrieval and handling of experiment data and apparatus configuration. Several materials, DMSO and m-tolunitrile, were selected as candidate fluids for the flow cell principally for their high dielectric constant which permits the high voltage power supply design to be held to 15 kV and still simulate terrestrial gravity. Achievement of a low dissipation factor in the fluid to minimize internal heating from the applied electrical field depends strongly on purification and handling procedures. The use of sapphire as the outer hemisphere for the flow cell provides excellent viewing conditions without a significant impact on attaining the desired thermal gradients. Birefringent effects from sapphire can be held to acceptably low limits. Visualization of flow fluid is achieved through the motion of a dot matrix formed by photochromic dyes. Two dyes found compatible with the candidate fluids are spiropyran and triarylmethane. The observation of the dot motion is accomplished using a flying spot scanner.

  7. Late Early Silurian (Wenlockian) paleoclimate using a general circulation model

    SciTech Connect

    Moore, G.T.; Hayashida, D.N.; Jacobson, S.R. ) Ross, C.A. )

    1992-01-01

    The Silurian Period (439--409 Ma) is synonymous with organic-rich, graptolitic, black shales. The physical conditions that prevailed during the Mid-Silurian drove the paleoclimate and controlled the deposition of this globally ubiquitous, lithotope. The paleoclimate in turn concomitantly created a paleoceanic environment favorable for the generation, deposition, and preservation of phytoplankton. A study of the relationship of the paleogeographic framework on the paleoclimate conditions that forced the deposition of this unique rock type is a problem suitable for study with a general circulation model. For this study the authors chose the Wenlockian Stage (430--424 Ma), the late Early Silurian. The Wenlockian physical world was composed of an oceanic northern hemisphere and a southern hemisphere dominated by the giant continent of Gondwana. The high latitude position of Gondwana placed much of its extensive margin in the mid-latitudes. Laurentia and Baltica occupied a tropical position while Siberia and Kazakh laid to the north. The Silurian fits a paleoatmosphere with an elevated greenhouse effect. Estimated Silurian values of atmospheric CO[sub 2] vary. They chose 1,120 ppm CO[sub 2], a value of 4[times] that of the pre-industrial level. The overall paleoclimate is forced by the diverse paleogeography of the two hemispheres. The northern hemisphere is dominated by strong zonality in all seasons. In contrast, the continental southern hemisphere reactors to the summer heating and winter cooling of Gondwana.

  8. Eddy processes in the general circulation of the Jovian atmospheres

    NASA Technical Reports Server (NTRS)

    Leovy, Conway

    1986-01-01

    Two fundamentally different views of the general circulation of Jovian atmospheres have emerged. According to one view, the observed jet streams at the cloud tops are controlled by the vorticity transfers of small scale eddies generated by planetary wave instabilities within a shallow atmospheric layer. According to the alternate point of view, the zonal jets are surface manifestations of deep interior convection organized into cylindrical motion with axes parallel to the planetary rotation axis. Both approaches may be considered in the context of the very different roles assumed by the potential vorticity. A possible reconciliation of the two kinds of dynamical systems is considered in which the interior motion is overlaid with a statically stable cappling layer driven by turbulent energy injection from below. A simple model for the eddy driving of quasi-geostrophic dynamics in the capping layer is presented which is consistent with the tentative evidence for up-gradient momentum flux on Jupiter and IRIS observations of thermal contrast correlations with cyclonic and anticyclonic shear zones. Certain synoptic-scale cloud features in Jupiter's atmosphere are interpreted as breaking waves, which may also influence the lateral mixing of tracers such as the ortho-para hydrogen ratio.

  9. Hospitable archean climates simulated by a general circulation model.

    PubMed

    Wolf, E T; Toon, O B

    2013-07-01

    Evidence from ancient sediments indicates that liquid water and primitive life were present during the Archean despite the faint young Sun. To date, studies of Archean climate typically utilize simplified one-dimensional models that ignore clouds and ice. Here, we use an atmospheric general circulation model coupled to a mixed-layer ocean model to simulate the climate circa 2.8 billion years ago when the Sun was 20% dimmer than it is today. Surface properties are assumed to be equal to those of the present day, while ocean heat transport varies as a function of sea ice extent. Present climate is duplicated with 0.06 bar of CO2 or alternatively with 0.02 bar of CO2 and 0.001 bar of CH4. Hot Archean climates, as implied by some isotopic reconstructions of ancient marine cherts, are unattainable even in our warmest simulation having 0.2 bar of CO2 and 0.001 bar of CH4. However, cooler climates with significant polar ice, but still dominated by open ocean, can be maintained with modest greenhouse gas amounts, posing no contradiction with CO2 constraints deduced from paleosols or with practical limitations on CH4 due to the formation of optically thick organic hazes. Our results indicate that a weak version of the faint young Sun paradox, requiring only that some portion of the planet's surface maintain liquid water, may be resolved with moderate greenhouse gas inventories. Thus, hospitable late Archean climates are easily obtained in our climate model.

  10. Application of Improved Radiation Modeling to General Circulation Models

    SciTech Connect

    Michael J Iacono

    2011-04-07

    This research has accomplished its primary objectives of developing accurate and efficient radiation codes, validating them with measurements and higher resolution models, and providing these advancements to the global modeling community to enhance the treatment of cloud and radiative processes in weather and climate prediction models. A critical component of this research has been the development of the longwave and shortwave broadband radiative transfer code for general circulation model (GCM) applications, RRTMG, which is based on the single-column reference code, RRTM, also developed at AER. RRTMG is a rigorously tested radiation model that retains a considerable level of accuracy relative to higher resolution models and measurements despite the performance enhancements that have made it possible to apply this radiation code successfully to global dynamical models. This model includes the radiative effects of all significant atmospheric gases, and it treats the absorption and scattering from liquid and ice clouds and aerosols. RRTMG also includes a statistical technique for representing small-scale cloud variability, such as cloud fraction and the vertical overlap of clouds, which has been shown to improve cloud radiative forcing in global models. This development approach has provided a direct link from observations to the enhanced radiative transfer provided by RRTMG for application to GCMs. Recent comparison of existing climate model radiation codes with high resolution models has documented the improved radiative forcing capability provided by RRTMG, especially at the surface, relative to other GCM radiation models. Due to its high accuracy, its connection to observations, and its computational efficiency, RRTMG has been implemented operationally in many national and international dynamical models to provide validated radiative transfer for improving weather forecasts and enhancing the prediction of global climate change.

  11. An atmospheric general circulation model for Pluto with predictions for New Horizons temperature profiles

    NASA Astrophysics Data System (ADS)

    Zalucha, Angela M.

    2016-06-01

    Results are presented from a 3D Pluto general circulation model (GCM) that includes conductive heating and cooling, non-local thermodynamic equilibrium (non-LTE) heating by methane at 2.3 and 3.3 μm, non-LTE cooling by cooling by methane at 7.6 μm, and LTE CO rotational line cooling. The GCM also includes a treatment of the subsurface temperature and surface-atmosphere mass exchange. An initially 1 m thick layer of surface nitrogen frost was assumed such that it was large enough to act as a large heat sink (compared with the solar heating term) but small enough that the water ice subsurface properties were also significant. Structure was found in all three directions of the 3D wind field (with a maximum magnitude of the order of 10 m s-1 in the horizontal directions and 10-5 microbar s-1 in the vertical direction). Prograde jets were found at several altitudes. The direction of flow over the poles was found to very with altitude. Broad regions of up-welling and down-welling were also found. Predictions of vertical temperature profiles are provided for the Alice and Radio science Experiment instruments on New Horizons, while predictions of light curves are provided for ground-based stellar occultation observations. With this model methane concentrations of 0.2 per cent and 1.0 per cent and 8 and 24 microbar surface pressures are distinguishable. For ground-based stellar occultations, a detectable difference exists between light curves with the different methane concentrations, but not for different initial global mean surface pressures.

  12. Mid-latitude afforestation shifts general circulation and tropical precipitation.

    PubMed

    Swann, Abigail L S; Fung, Inez Y; Chiang, John C H

    2012-01-17

    We show in climate model experiments that large-scale afforestation in northern mid-latitudes warms the Northern Hemisphere and alters global circulation patterns. An expansion of dark forests increases the absorption of solar energy and increases surface temperature, particularly in regions where the land surface is unable to compensate with latent heat flux due to water limitation. Atmospheric circulation redistributes the anomalous energy absorbed in the northern hemisphere, in particular toward the south, through altering the Hadley circulation, resulting in the northward displacement of the tropical rain bands. Precipitation decreases over parts of the Amazon basin affecting productivity and increases over the Sahel and Sahara regions in Africa. We find that the response of climate to afforestation in mid-latitudes is determined by the amount of soil moisture available to plants with the greatest warming found in water-limited regions. Mid-latitude afforestation is found to have a small impact on modeled global temperatures and on global CO(2), but regional heating from the increase in forest cover is capable of driving unintended changes in circulation and precipitation. The ability of vegetation to affect remote circulation has implications for strategies for climate mitigation.

  13. Mid-latitude afforestation shifts general circulation and tropical precipitation

    PubMed Central

    Swann, Abigail L. S.; Fung, Inez Y.; Chiang, John C. H.

    2012-01-01

    We show in climate model experiments that large-scale afforestation in northern mid-latitudes warms the Northern Hemisphere and alters global circulation patterns. An expansion of dark forests increases the absorption of solar energy and increases surface temperature, particularly in regions where the land surface is unable to compensate with latent heat flux due to water limitation. Atmospheric circulation redistributes the anomalous energy absorbed in the northern hemisphere, in particular toward the south, through altering the Hadley circulation, resulting in the northward displacement of the tropical rain bands. Precipitation decreases over parts of the Amazon basin affecting productivity and increases over the Sahel and Sahara regions in Africa. We find that the response of climate to afforestation in mid-latitudes is determined by the amount of soil moisture available to plants with the greatest warming found in water-limited regions. Mid-latitude afforestation is found to have a small impact on modeled global temperatures and on global CO2, but regional heating from the increase in forest cover is capable of driving unintended changes in circulation and precipitation. The ability of vegetation to affect remote circulation has implications for strategies for climate mitigation. PMID:22190490

  14. Bootstrapping 3D fermions

    DOE PAGES

    Iliesiu, Luca; Kos, Filip; Poland, David; ...

    2016-03-17

    We study the conformal bootstrap for a 4-point function of fermions <ψψψψ> in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge CT. We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N. Finally, we also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.

  15. Bootstrapping 3D fermions

    SciTech Connect

    Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David; Yacoby, Ran

    2016-03-17

    We study the conformal bootstrap for a 4-point function of fermions <ψψψψ> in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge CT. We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N. Finally, we also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.

  16. Jupiter Thermospheric General Circulation Model (JTGCM): Global Structure and Dynamics Driven by Auroral and Joule Heating

    NASA Technical Reports Server (NTRS)

    Bougher, S. W.; J. Il. Waite, Jr.; Majeed, T.

    2005-01-01

    A growing multispectral database plus recent Galileo descent measurements are being used to construct a self-consistent picture of the Jupiter thermosphere/ionosphere system. The proper characterization of Jupiter s upper atmosphere, embedded ionosphere, and auroral features requires the examination of underlying processes, including the feedbacks of energetics, neutral-ion dynamics, composition, and magnetospheric coupling. A fully 3-D Jupiter Thermospheric General Circulation Model (JTGCM) has been developed and exercised to address global temperatures, three-component neutral winds, and neutral-ion species distributions. The domain of this JTGCM extends from 20-microbar (capturing hydrocarbon cooling) to 1.0 x 10(exp -4) nbar (including aurora/Joule heating processes). The resulting JTGCM has been fully spun-up and integrated for greater than or equal to40 Jupiter rotations. Results from three JTGCM cases incorporating moderate auroral heating, ion drag, and moderate to strong Joule heating processes are presented. The neutral horizontal winds at ionospheric heights vary from 0.5 km/s to 1.2 km/s, atomic hydrogen is transported equatorward, and auroral exospheric temperatures range from approx.1200-1300 K to above 3000 K, depending on the magnitude of Joule heating. The equatorial temperature profiles from the JTGCM are compared with the measured temperature structure from the Galileo AS1 data set. The best fit to the Galileo data implies that the major energy source for maintaining the equatorial temperatures is due to dynamical heating induced by the low-latitude convergence of the high-latitude-driven thermospheric circulation. Overall, the Jupiter thermosphere/ionosphere system is highly variable and is shown to be strongly dependent on magnetospheric coupling which regulates Joule heating.

  17. Development of a numerical procedure to map a general 3-d body onto a near-circle

    NASA Technical Reports Server (NTRS)

    Hommel, M. J.

    1986-01-01

    Conformal mapping is a classical technique utilized for solving problems in aerodynamics and hydrodynamics. Conformal mapping is utilized in the construction of grids around airfoils, engine inlets and other aircraft configurations. These shapes are transformed onto a near-circle image for which the equations of fluid motion are discretized on the mapped plane and solved numerically by utilizing the appropriate techniques. In comparison to other grid-generation techniques such as algerbraic or differential type, conformal mapping offers an analytical and accurate form even if the grid deformation is large. One of the most appealing features is that the grid can be constrained to remain orthogonal to the body after the transformation. Hence, the grid is suitable for analyzing the supersonic flow past a blunt object. The associated shock as a coordinate surface adjusts its position in the course of computation until convergence is reached. The present work applied conformal mapping to 3-D bodies with no axis of symmetry such as the Aerobraking Flight Experiment (AFE) vehicle, transforming the AFE shape onto a near-circle image. A numerical procedure and code are used to generate grids around the AFE body.

  18. Radiochromic 3D Detectors

    NASA Astrophysics Data System (ADS)

    Oldham, Mark

    2015-01-01

    Radiochromic materials exhibit a colour change when exposed to ionising radiation. Radiochromic film has been used for clinical dosimetry for many years and increasingly so recently, as films of higher sensitivities have become available. The two principle advantages of radiochromic dosimetry include greater tissue equivalence (radiologically) and the lack of requirement for development of the colour change. In a radiochromic material, the colour change arises direct from ionising interactions affecting dye molecules, without requiring any latent chemical, optical or thermal development, with important implications for increased accuracy and convenience. It is only relatively recently however, that 3D radiochromic dosimetry has become possible. In this article we review recent developments and the current state-of-the-art of 3D radiochromic dosimetry, and the potential for a more comprehensive solution for the verification of complex radiation therapy treatments, and 3D dose measurement in general.

  19. Adaptive Error Estimation in Linearized Ocean General Circulation Models

    NASA Technical Reports Server (NTRS)

    Chechelnitsky, Michael Y.

    1999-01-01

    Data assimilation methods are routinely used in oceanography. The statistics of the model and measurement errors need to be specified a priori. This study addresses the problem of estimating model and measurement error statistics from observations. We start by testing innovation based methods of adaptive error estimation with low-dimensional models in the North Pacific (5-60 deg N, 132-252 deg E) to TOPEX/POSEIDON (TIP) sea level anomaly data, acoustic tomography data from the ATOC project, and the MIT General Circulation Model (GCM). A reduced state linear model that describes large scale internal (baroclinic) error dynamics is used. The methods are shown to be sensitive to the initial guess for the error statistics and the type of observations. A new off-line approach is developed, the covariance matching approach (CMA), where covariance matrices of model-data residuals are "matched" to their theoretical expectations using familiar least squares methods. This method uses observations directly instead of the innovations sequence and is shown to be related to the MT method and the method of Fu et al. (1993). Twin experiments using the same linearized MIT GCM suggest that altimetric data are ill-suited to the estimation of internal GCM errors, but that such estimates can in theory be obtained using acoustic data. The CMA is then applied to T/P sea level anomaly data and a linearization of a global GFDL GCM which uses two vertical modes. We show that the CMA method can be used with a global model and a global data set, and that the estimates of the error statistics are robust. We show that the fraction of the GCM-T/P residual variance explained by the model error is larger than that derived in Fukumori et al.(1999) with the method of Fu et al.(1993). Most of the model error is explained by the barotropic mode. However, we find that impact of the change in the error statistics on the data assimilation estimates is very small. This is explained by the large

  20. Venusian Polar Vortex reproduced in an Atmospheric General Circulation Model

    NASA Astrophysics Data System (ADS)

    Ando, Hiroki; Imamura, Takeshi; Takagi, Masahiro; Sugimoto, Norihiko; Kashimura, Hiroki

    The Venus atmosphere has a polar vortex rotating in the retrograde direction with a period of about three days. The vortex has a warm feature surrounded by a cold collar (e.g., Taylor et al. 1980; Piccioni et al. 2006). Although the Venusian polar vortex has been reported by many observations, its mechanism is still unknown. Elson (1982, 1989) examined the structure of the polar vortex by linear calculations. However, the background zonal wind assumed in the calculations was much stronger or weaker than those retrieved in the previous measurements (e.g., Peralta et al. 2008; Kouyama et al. 2012). Lee et al. (2010) and Yamamoto and Takahashi (2012) performed numerical simulations with general circulation models (GCMs) of the Venus atmosphere and obtained vertical structure in the polar region. However, the models included artificial forcing of Kelvin and/or Rossby waves. We have developed a new Venusian GCM by modifying the Atmospheric GCM For the Earth Simulator (Sugimoto et al. 2012; 2013). The basic equations of the GCM are primitive ones in the sigma coordinate on a sphere without topography. The model resolution is T42 (i.e., about 2.8 deg x 2.8 deg grids) and L60 (Deltaz is about 2 km). Rayleigh friction (sponge layer) in the upper layer (>80 km) is applied to prevent the reflection of waves, whose effect increases gradually with height. In the model, the atmosphere is dry and forced by the solar heating and Newtonian cooling. The vertical profile of the solar heating is based on Crisp (1986), and zonally averaged distribution is used. In addition diurnal component of the solar heating, which excites the diurnal and semi-diurnal tides, is also included. Newtonian cooling relaxes the temperature to the zonally uniform basic temperature which has a virtual static stability of Venus with almost neutral layers, and its coefficient is based on Crisp (1986). To prevent numerical instability, the biharmonic hyper-diffusion is included with 0.8 days of e-folding time

  1. Correcting circulation biases in a lower-resolution global general circulation model with data assimilation

    NASA Astrophysics Data System (ADS)

    Canter, Martin; Barth, Alexander; Beckers, Jean-Marie

    2016-12-01

    In this study, we aim at developing a new method of bias correction using data assimilation. This method is based on the stochastic forcing of a model to correct bias by directly adding an additional source term into the model equations. This method is presented and tested first with a twin experiment on a fully controlled Lorenz '96 model. It is then applied to the lower-resolution global circulation NEMO-LIM2 model, with both a twin experiment and a real case experiment. Sea surface height observations are used to create a forcing to correct the poorly located and estimated currents. Validation is then performed throughout the use of other variables such as sea surface temperature and salinity. Results show that the method is able to consistently correct part of the model bias. The bias correction term is presented and is consistent with the limitations of the global circulation model causing bias on the oceanic currents.

  2. Correcting circulation biases in a lower-resolution global general circulation model with data assimilation

    NASA Astrophysics Data System (ADS)

    Canter, Martin; Barth, Alexander; Beckers, Jean-Marie

    2017-02-01

    In this study, we aim at developing a new method of bias correction using data assimilation. This method is based on the stochastic forcing of a model to correct bias by directly adding an additional source term into the model equations. This method is presented and tested first with a twin experiment on a fully controlled Lorenz '96 model. It is then applied to the lower-resolution global circulation NEMO-LIM2 model, with both a twin experiment and a real case experiment. Sea surface height observations are used to create a forcing to correct the poorly located and estimated currents. Validation is then performed throughout the use of other variables such as sea surface temperature and salinity. Results show that the method is able to consistently correct part of the model bias. The bias correction term is presented and is consistent with the limitations of the global circulation model causing bias on the oceanic currents.

  3. General principles of describing second- and higher-order null points of a potential magnetic field in 3D

    NASA Astrophysics Data System (ADS)

    Lukashenko, A. T.; Veselovsky, I. S.

    2015-12-01

    General principles of describing secondand higher-order null points of a potential magnetic field are formulated. The potential near a second-order null of the general form can be specified by a linear combination of four basic functions, the list of which is presented. Near secondand higher-order null points, field line equations often cannot be integrated analytically; however, in some cases, it is possible to present a qualitative description of the geometry of null vicinities with consideration of the behavior of field lines near rays outgoing from null, at which the field is radial or equals zero.

  4. Ultra-high-density 3D DNA arrays within nanoporous biocompatible membranes for single-molecule-level detection and purification of circulating nucleic acids

    NASA Astrophysics Data System (ADS)

    Aramesh, M.; Shimoni, O.; Fox, K.; Karle, T. J.; Lohrmann, A.; Ostrikov, K.; Prawer, S.; Cervenka, J.

    2015-03-01

    Extracellular nucleic acids freely circulating in blood and other physiologic fluids are important biomarkers for non-invasive diagnostics and early detection of cancer and other diseases, yet difficult to detect because they exist in very low concentrations and large volumes. Here we demonstrate a new broad-range sensor platform for ultrasensitive and selective detection of circulating DNA down to the single-molecule level. The biosensor is based on a chemically functionalized nanoporous diamond-like carbon (DLC) coated alumina membrane. The few nanometer-thick, yet perfect and continuous DLC-coating confers the chemical stability and biocompatibility of the sensor, allowing its direct application in biological conditions. The selective detection is based on complementary hybridization of a fluorescently-tagged circulating cancer oncomarker (a 21-mer nucleic acid) with covalently immobilized DNA on the surface of the membrane. The captured DNAs are detected in the nanoporous structure of the sensor using confocal scanning laser microscopy. The flow-through membrane sensor demonstrates broad-range sensitivity, spanning from 1015 molecules per cm2 down to single molecules, which is several orders of magnitude improvement compared to the flat DNA microarrays. Our study suggests that these flow-through type nanoporous sensors represent a new powerful platform for large volume sampling and ultrasensitive detection of different chemical biomarkers.Extracellular nucleic acids freely circulating in blood and other physiologic fluids are important biomarkers for non-invasive diagnostics and early detection of cancer and other diseases, yet difficult to detect because they exist in very low concentrations and large volumes. Here we demonstrate a new broad-range sensor platform for ultrasensitive and selective detection of circulating DNA down to the single-molecule level. The biosensor is based on a chemically functionalized nanoporous diamond-like carbon (DLC) coated

  5. Circulation and rainfall climatology of a 10-year (1979 - 1988) integration with the Goddard Laboratory for atmospheres general circulation model

    NASA Technical Reports Server (NTRS)

    Kim, J.-H.; Sud, Y. C.

    1993-01-01

    A 10-year (1979-1988) integration of Goddard Laboratory for Atmospheres (GLA) general circulation model (GCM) under Atmospheric Model Intercomparison Project (AMIP) is analyzed and compared with observation. The first momentum fields of circulation variables and also hydrological variables including precipitation, evaporation, and soil moisture are presented. Our goals are (1) to produce a benchmark documentation of the GLA GCM for future model improvements; (2) to examine systematic errors between the simulated and the observed circulation, precipitation, and hydrologic cycle; (3) to examine the interannual variability of the simulated atmosphere and compare it with observation; and (4) to examine the ability of the model to capture the major climate anomalies in response to events such as El Nino and La Nina. The 10-year mean seasonal and annual simulated circulation is quite reasonable compared to the analyzed circulation, except the polar regions and area of high orography. Precipitation over tropics are quite well simulated, and the signal of El Nino/La Nina episodes can be easily identified. The time series of evaporation and soil moisture in the 12 biomes of the biosphere also show reasonable patterns compared to the estimated evaporation and soil moisture.

  6. Coupling 3D groundwater modeling with CFC-based age dating to classify local groundwater circulation in an unconfined crystalline aquifer

    NASA Astrophysics Data System (ADS)

    Kolbe, Tamara; Marçais, Jean; Thomas, Zahra; Abbott, Benjamin W.; de Dreuzy, Jean-Raynald; Rousseau-Gueutin, Pauline; Aquilina, Luc; Labasque, Thierry; Pinay, Gilles

    2016-12-01

    Nitrogen pollution of freshwater and estuarine environments is one of the most urgent environmental crises. Shallow aquifers with predominantly local flow circulation are particularly vulnerable to agricultural contaminants. Water transit time and flow path are key controls on catchment nitrogen retention and removal capacity, but the relative importance of hydrogeological and topographical factors in determining these parameters is still uncertain. We used groundwater dating and numerical modeling techniques to assess transit time and flow path in an unconfined aquifer in Brittany, France. The 35.5 km2 study catchment has a crystalline basement underneath a ∼60 m thick weathered and fractured layer, and is separated into a distinct upland and lowland area by an 80 m-high butte. We used groundwater discharge and groundwater ages derived from chlorofluorocarbon (CFC) concentration to calibrate a free-surface flow model simulating groundwater flow circulation. We found that groundwater flow was highly local (mean travel distance = 350 m), substantially smaller than the typical distance between neighboring streams (∼1 km), while CFC-based ages were quite old (mean = 40 years). Sensitivity analysis revealed that groundwater travel distances were not sensitive to geological parameters (i.e. arrangement of geological layers and permeability profile) within the constraints of the CFC age data. However, circulation was sensitive to topography in the lowland area where the water table was near the land surface, and to recharge rate in the upland area where water input modulated the free surface of the aquifer. We quantified these differences with a local groundwater ratio (rGW-LOCAL), defined as the mean groundwater travel distance divided by the mean of the reference surface distances (the distance water would have to travel across the surface of the digital elevation model). Lowland, rGW-LOCAL was near 1, indicating primarily topographical controls. Upland, r

  7. 3D Geological Modeling of the General Separations Area, Savannah River Site: A Preliminary Workflow and Model

    SciTech Connect

    Flach, G.P.

    2002-10-29

    The Savannah River Site, located in South Carolina, contains nuclear defense products and nuclear waste byproducts as result of national defense operations dating to the 1950s. The facility has been the subject of a variety of scientific investigations focusing on potential groundwater transportation of nuclides and other hazardous materials through the different aquifers within the air. The area of particular interest, and the subject of this report, is the General Separations Area.

  8. MTS-MD of Biomolecules Steered with 3D-RISM-KH Mean Solvation Forces Accelerated with Generalized Solvation Force Extrapolation.

    PubMed

    Omelyan, Igor; Kovalenko, Andriy

    2015-04-14

    We developed a generalized solvation force extrapolation (GSFE) approach to speed up multiple time step molecular dynamics (MTS-MD) of biomolecules steered with mean solvation forces obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model with the Kovalenko-Hirata closure). GSFE is based on a set of techniques including the non-Eckart-like transformation of coordinate space separately for each solute atom, extension of the force-coordinate pair basis set followed by selection of the best subset, balancing the normal equations by modified least-squares minimization of deviations, and incremental increase of outer time step in motion integration. Mean solvation forces acting on the biomolecule atoms in conformations at successive inner time steps are extrapolated using a relatively small number of best (closest) solute atomic coordinates and corresponding mean solvation forces obtained at previous outer time steps by converging the 3D-RISM-KH integral equations. The MTS-MD evolution steered with GSFE of 3D-RISM-KH mean solvation forces is efficiently stabilized with our optimized isokinetic Nosé-Hoover chain (OIN) thermostat. We validated the hybrid MTS-MD/OIN/GSFE/3D-RISM-KH integrator on solvated organic and biomolecules of different stiffness and complexity: asphaltene dimer in toluene solvent, hydrated alanine dipeptide, miniprotein 1L2Y, and protein G. The GSFE accuracy and the OIN efficiency allowed us to enlarge outer time steps up to huge values of 1-4 ps while accurately reproducing conformational properties. Quasidynamics steered with 3D-RISM-KH mean solvation forces achieves time scale compression of conformational changes coupled with solvent exchange, resulting in further significant acceleration of protein conformational sampling with respect to real time dynamics. Overall, this provided a 50- to 1000-fold effective speedup of conformational sampling for these systems, compared to conventional MD

  9. Use of weather types to disaggregate general circulation model predictions

    USGS Publications Warehouse

    Hay, L.E.; McCabe, G.J.; Wolock, D.M.; Ayers, M.A.

    1992-01-01

    A method has been developed that uses weather-type analysis as a tool to spatially disaggregate GCM predictions to make them useful for water resource studies. The method has been applied to the Delaware River basin to predict the effects of doubling atmospheric carbon dioxide on precipitation patterns in the region. An application of the technique to the Delaware River basin indicates that future climate conditions will show minimal changes in weather-type frequency, implying that air circulation patterns will remain unchanged -from Authors

  10. INS3D - NUMERICAL SOLUTION OF THE INCOMPRESSIBLE NAVIER-STOKES EQUATIONS IN THREE-DIMENSIONAL GENERALIZED CURVILINEAR COORDINATES (IBM VERSION)

    NASA Technical Reports Server (NTRS)

    Kwak, D.

    1994-01-01

    INS3D computes steady-state solutions to the incompressible Navier-Stokes equations. The INS3D approach utilizes pseudo-compressibility combined with an approximate factorization scheme. This computational fluid dynamics (CFD) code has been verified on problems such as flow through a channel, flow over a backwardfacing step and flow over a circular cylinder. Three dimensional cases include flow over an ogive cylinder, flow through a rectangular duct, wind tunnel inlet flow, cylinder-wall juncture flow and flow through multiple posts mounted between two plates. INS3D uses a pseudo-compressibility approach in which a time derivative of pressure is added to the continuity equation, which together with the momentum equations form a set of four equations with pressure and velocity as the dependent variables. The equations' coordinates are transformed for general three dimensional applications. The equations are advanced in time by the implicit, non-iterative, approximately-factored, finite-difference scheme of Beam and Warming. The numerical stability of the scheme depends on the use of higher-order smoothing terms to damp out higher-frequency oscillations caused by second-order central differencing. The artificial compressibility introduces pressure (sound) waves of finite speed (whereas the speed of sound would be infinite in an incompressible fluid). As the solution converges, these pressure waves die out, causing the derivation of pressure with respect to time to approach zero. Thus, continuity is satisfied for the incompressible fluid in the steady state. Computational efficiency is achieved using a diagonal algorithm. A block tri-diagonal option is also available. When a steady-state solution is reached, the modified continuity equation will satisfy the divergence-free velocity field condition. INS3D is capable of handling several different types of boundaries encountered in numerical simulations, including solid-surface, inflow and outflow, and far

  11. INS3D - NUMERICAL SOLUTION OF THE INCOMPRESSIBLE NAVIER-STOKES EQUATIONS IN THREE-DIMENSIONAL GENERALIZED CURVILINEAR COORDINATES (DEC RISC ULTRIX VERSION)

    NASA Technical Reports Server (NTRS)

    Biyabani, S. R.

    1994-01-01

    INS3D computes steady-state solutions to the incompressible Navier-Stokes equations. The INS3D approach utilizes pseudo-compressibility combined with an approximate factorization scheme. This computational fluid dynamics (CFD) code has been verified on problems such as flow through a channel, flow over a backwardfacing step and flow over a circular cylinder. Three dimensional cases include flow over an ogive cylinder, flow through a rectangular duct, wind tunnel inlet flow, cylinder-wall juncture flow and flow through multiple posts mounted between two plates. INS3D uses a pseudo-compressibility approach in which a time derivative of pressure is added to the continuity equation, which together with the momentum equations form a set of four equations with pressure and velocity as the dependent variables. The equations' coordinates are transformed for general three dimensional applications. The equations are advanced in time by the implicit, non-iterative, approximately-factored, finite-difference scheme of Beam and Warming. The numerical stability of the scheme depends on the use of higher-order smoothing terms to damp out higher-frequency oscillations caused by second-order central differencing. The artificial compressibility introduces pressure (sound) waves of finite speed (whereas the speed of sound would be infinite in an incompressible fluid). As the solution converges, these pressure waves die out, causing the derivation of pressure with respect to time to approach zero. Thus, continuity is satisfied for the incompressible fluid in the steady state. Computational efficiency is achieved using a diagonal algorithm. A block tri-diagonal option is also available. When a steady-state solution is reached, the modified continuity equation will satisfy the divergence-free velocity field condition. INS3D is capable of handling several different types of boundaries encountered in numerical simulations, including solid-surface, inflow and outflow, and far

  12. Mariage des maillages: A new 3D general relativistic hydro code for simulation of gravitational waves from core-collapses.

    NASA Astrophysics Data System (ADS)

    Novak, Jerome; Dimmelmeier, Harrald; Font-Roda, Jose A.

    2004-12-01

    We present a new three-dimensional general relativistic hydrodynamics code which can be applied to study stellar core collapses and the resulting gravitational radiation. This code uses two different numerical techniques to solve partial differential equations arising in the model: high-resolution shock capturing (HRSC) schemes for the evolution of hydrodynamic quantities and spectral methods for the solution of Einstein equations. The equations are written and solved using spherical polar coordinates, best suited to stellar topology. Einstein equations are formulated within the 3+1 formalism and conformal flat condition (CFC) for the 3-metric and gravitational radiation is extracted using Newtonian quadrupole formulation.

  13. Recent Upgrades to the NASA Ames Mars General Circulation Model: Applications to Mars' Water Cycle

    NASA Astrophysics Data System (ADS)

    Hollingsworth, Jeffery L.; Kahre, M. A.; Haberle, R. M.; Montmessin, F.; Wilson, R. J.; Schaeffer, J.

    2008-09-01

    We report on recent improvements to the NASA Ames Mars general circulation model (GCM), a robust 3D climate-modeling tool that is state-of-the-art in terms of its physics parameterizations and subgrid-scale processes, and which can be applied to investigate physical and dynamical processes of the present (and past) Mars climate system. The most recent version (gcm2.1, v.24) of the Ames Mars GCM utilizes a more generalized radiation code (based on a two-stream approximation with correlated k's); an updated transport scheme (van Leer formulation); a cloud microphysics scheme that assumes a log-normal particle size distribution whose first two moments are treated as atmospheric tracers, and which includes the nucleation, growth and sedimentation of ice crystals. Atmospheric aerosols (e.g., dust and water-ice) can either be radiatively active or inactive. We apply this version of the Ames GCM to investigate key aspects of the present water cycle on Mars. Atmospheric dust is partially interactive in our simulations; namely, the radiation code "sees" a prescribed distribution that follows the MGS thermal emission spectrometer (TES) year-one measurements with a self-consistent vertical depth scale that varies with season. The cloud microphysics code interacts with a transported dust tracer column whose surface source is adjusted to maintain the TES distribution. The model is run from an initially dry state with a better representation of the north residual cap (NRC) which accounts for both surface-ice and bare-soil components. A seasonally repeatable water cycle is obtained within five Mars years. Our sub-grid scale representation of the NRC provides for a more realistic flux of moisture to the atmosphere and a much drier water cycle consistent with recent spacecraft observations (e.g., Mars Express PFS, corrected MGS/TES) compared to models that assume a spatially uniform and homogeneous north residual polar cap.

  14. Bending analysis of a general cross-ply laminate using 3D elasticity solution and layerwise theory

    NASA Astrophysics Data System (ADS)

    Yazdani Sarvestani, H.; Naghashpour, A.; Heidari-Rarani, M.

    2015-12-01

    In this study, the analytical solution of interlaminar stresses near the free edges of a general (symmetric and unsymmetric layups) cross-ply composite laminate subjected to pure bending loading is presented based on Reddy's layerwise theory (LWT) for the first time. First, the reduced form of displacement field is obtained for a general cross-ply composite laminate subjected to a bending moment by elasticity theory. Then, first-order shear deformation theory of plates and LWT is utilized to determine the global and local deformation parameters appearing in the displacement fields, respectively. One of the main advantages of the developed solution based on the LWT is exact prediction of interlaminar stresses at the boundary layer regions. To show the accuracy of this solution, three-dimensional elasticity bending problem of a laminated composite is solved for special set of boundary conditions as well. Finally, LWT results are presented for edge-effect problems of several symmetric and unsymmetric cross-ply laminates under the bending moment. The obtained results indicate high stress gradients of interlaminar stresses near the edges of laminates.

  15. General fusion approaches for the age determination of latent fingerprint traces: results for 2D and 3D binary pixel feature fusion

    NASA Astrophysics Data System (ADS)

    Merkel, Ronny; Gruhn, Stefan; Dittmann, Jana; Vielhauer, Claus; Bräutigam, Anja

    2012-03-01

    Determining the age of latent fingerprint traces found at crime scenes is an unresolved research issue since decades. Solving this issue could provide criminal investigators with the specific time a fingerprint trace was left on a surface, and therefore would enable them to link potential suspects to the time a crime took place as well as to reconstruct the sequence of events or eliminate irrelevant fingerprints to ensure privacy constraints. Transferring imaging techniques from different application areas, such as 3D image acquisition, surface measurement and chemical analysis to the domain of lifting latent biometric fingerprint traces is an upcoming trend in forensics. Such non-destructive sensor devices might help to solve the challenge of determining the age of a latent fingerprint trace, since it provides the opportunity to create time series and process them using pattern recognition techniques and statistical methods on digitized 2D, 3D and chemical data, rather than classical, contact-based capturing techniques, which alter the fingerprint trace and therefore make continuous scans impossible. In prior work, we have suggested to use a feature called binary pixel, which is a novel approach in the working field of fingerprint age determination. The feature uses a Chromatic White Light (CWL) image sensor to continuously scan a fingerprint trace over time and retrieves a characteristic logarithmic aging tendency for 2D-intensity as well as 3D-topographic images from the sensor. In this paper, we propose to combine such two characteristic aging features with other 2D and 3D features from the domains of surface measurement, microscopy, photography and spectroscopy, to achieve an increase in accuracy and reliability of a potential future age determination scheme. Discussing the feasibility of such variety of sensor devices and possible aging features, we propose a general fusion approach, which might combine promising features to a joint age determination scheme

  16. Influence of land surface roughness on atmospheric circulation and precipitation - A sensitivity study with a general circulation model

    NASA Technical Reports Server (NTRS)

    Sud, Y. C.; Shukla, J.; Mintz, Y.

    1988-01-01

    The influence of land surface roughness on the large scale atmospheric circulation and rainfall is examined by comparing three sets of simulations made with a general circulation model in which the land surface roughness length, z(0), was reduced from 45 cm to 0.02 cm. It is found that the reduced surface roughness produced a two-fold increase in the boundary layer wind speed, a two-fold decrease in the magnitude of the surface stress, and almost no change in the surface evaporation and surface sensible heat flux. It is suggested that the height of the earth's vegetation cover has a large influence on the boundary layer water vapor transport convergence and the rainfall distribution.

  17. Constraints on Saturn's Tropospheric General Circulation from Cassini ISS Images

    NASA Technical Reports Server (NTRS)

    DelGenio, Anthony D.; Barbara, John M.

    2013-01-01

    An automated cloud tracking algorithm is applied to Cassini Imaging Science Subsystem high-resolution apoapsis images of Saturn from 2005 and 2007 and moderate resolution images from 2011 and 2012 to define the near-global distribution of zonal winds and eddy momentum fluxes at the middle troposphere cloud level and in the upper troposphere haze. Improvements in the tracking algorithm combined with the greater feature contrast in the northern hemisphere during the approach to spring equinox allow for better rejection of erroneous wind vectors, a more objective assessment at any latitude of the quality of the mean zonal wind, and a population of winds comparable in size to that available for the much higher contrast atmosphere of Jupiter. Zonal winds at cloud level changed little between 2005 and 2007 at all latitudes sampled. Upper troposphere zonal winds derived from methane band images are approx. 10 m/s weaker than cloud level winds in the cores of eastward jets and approx. 5 m/s stronger on either side of the jet core, i.e., eastward jets appear to broaden with increasing altitude. In westward jet regions winds are approximately the same at both altitudes. Lateral eddy momentum fluxes are directed into eastward jet cores, including the strong equatorial jet, and away from westward jet cores and weaken with increasing altitude on the flanks of the eastward jets, consistent with the upward broadening of these jets. The conversion rate of eddy to mean zonal kinetic energy at the visible cloud level is larger in eastward jet regions (5.2x10(exp -5) sq m/s) and smaller in westward jet regions (1.6x10(exp -5) sqm/s) than the global mean value (4.1x10(ep -5) sq m/s). Overall the results are consistent with theories that suggest that the jets and the overturning meridional circulation at cloud level on Saturn are maintained at least in part by eddies due to instabilities of the large-scale flow near and/or below the cloud level.

  18. A Wind Tunnel Model to Explore Unsteady Circulation Control for General Aviation Applications

    NASA Technical Reports Server (NTRS)

    Cagle, Christopher M.; Jones, Gregory S.

    2002-01-01

    Circulation Control airfoils have been demonstrated to provide substantial improvements in lift over conventional airfoils. The General Aviation Circular Control model is an attempt to address some of the concerns of this technique. The primary focus is to substantially reduce the amount of air mass flow by implementing unsteady flow. This paper describes a wind tunnel model that implements unsteady circulation control by pulsing internal pneumatic valves and details some preliminary results from the first test entry.

  19. Anisotropic mesoscale eddy transport in ocean general circulation models

    NASA Astrophysics Data System (ADS)

    Reckinger, Scott; Fox-Kemper, Baylor; Bachman, Scott; Bryan, Frank; Dennis, John; Danabasoglu, Gokhan

    2014-11-01

    In modern climate models, the effects of oceanic mesoscale eddies are introduced by relating subgrid eddy fluxes to the resolved gradients of buoyancy or other tracers, where the proportionality is, in general, governed by an eddy transport tensor. The symmetric part of the tensor, which represents the diffusive effects of mesoscale eddies, is universally treated isotropically. However, the diffusive processes that the parameterization approximates, such as shear dispersion and potential vorticity barriers, typically have strongly anisotropic characteristics. Generalizing the eddy diffusivity tensor for anisotropy extends the number of parameters from one to three: major diffusivity, minor diffusivity, and alignment. The Community Earth System Model (CESM) with the anisotropic eddy parameterization is used to test various choices for the parameters, which are motivated by observations and the eddy transport tensor diagnosed from high resolution simulations. Simply setting the ratio of major to minor diffusivities to a value of five globally, while aligning the major axis along the flow direction, improves biogeochemical tracer ventilation and reduces temperature and salinity biases. These effects can be improved by parameterizing the oceanic anisotropic transport mechanisms.

  20. The general circulation of the Baltic Sea in the context of climate variability

    NASA Astrophysics Data System (ADS)

    Getzlaff, K.; Lehmann, A.

    2012-04-01

    A detailed assessment of climate variability of the Baltic Sea area for the period 1958-2009 revealed that the recent changes in the warming trend since the mid-1980s are associated with changes in the large-scale atmospheric circulation over the North Atlantic. The analysis of winter sea level pressure (SLP) data highlighted considerable changes in the number and pathways of deep cyclones (<980 hPa) in parallel with the eastward shift of the North Atlantic Oscillation (NAO) centres of action. Additionally, a seasonal shift of strong wind events from autumn to winter and early spring exists for the Baltic area. Earlier studies showed that different atmospheric climate regimes force different circulation regimes in the Baltic Sea. The analysis of the winter (DJFM) circulation patterns for the period 1970-2008 reveals changes in the general circulation of the Baltic Sea. While it is difficult to clearly link individual winter circulation patterns to one of the four dominant atmospheric climate regimes for the North Atlantic domain, the comparison of mean winter circulation patterns for 20-year periods (1970-1989 and 1990-2009) highlights that for the later 20-year period an intensified cyclonic circulation exists in the central Baltic Sea. This intensified circulation results from stronger westerly and north-westerly winds and is most likely connected to changes in the large-scale atmospheric circulation. As climate, to a large extent, controls patterns of water circulation and biophysical aspects relevant for biological production, such as the vertical distribution of temperature, salinity and oxygen, alterations in climate may severely impact the trophic structure and functioning of marine food webs.

  1. An Active Flow Circulation Controlled Flap Concept for General Aviation Aircraft Applications

    NASA Technical Reports Server (NTRS)

    Jones, Gregory S.; Viken, Sally A.; Washburn, Anthony E.; Jenkins, Luther N.; Cagle, C. Mark

    2002-01-01

    A recent focus on revolutionary aerodynamic concepts has highlighted the technology needs of general aviation and personal aircraft. New and stringent restrictions on these types of aircraft have placed high demands on aerodynamic performance, noise, and environmental issues. Improved high lift performance of these aircraft can lead to slower takeoff and landing speeds that can be related to reduced noise and crash survivability issues. Circulation Control technologies have been around for 65 years, yet have been avoided due to trade offs of mass flow, pitching moment, perceived noise etc. The need to improve the circulation control technology for general aviation and personal air-vehicle applications is the focus of this paper. This report will describe the development of a 2-D General Aviation Circulation Control (GACC) wing concept that utilizes a pulsed pneumatic flap.

  2. Circulation control propellers for general aviation, including a BASIC computer program

    NASA Technical Reports Server (NTRS)

    Taback, I.; Braslow, A. L.; Butterfield, A. J.

    1983-01-01

    The feasibility of replacing variable pitch propeller mechanisms with circulation control (Coanada effect) propellers on general aviation airplanes was examined. The study used a specially developed computer program written in BASIC which could compare the aerodynamic performance of circulation control propellers with conventional propellers. The comparison of aerodynamic performance for circulation control, fixed pitch and variable pitch propellers is based upon the requirements for a 1600 kg (3600 lb) single engine general aviation aircraft. A circulation control propeller using a supercritical airfoil was shown feasible over a representative range of design conditions. At a design condition for high speed cruise, all three types of propellers showed approximately the same performance. At low speed, the performance of the circulation control propeller exceeded the performance for a fixed pitch propeller, but did not match the performance available from a variable pitch propeller. It appears feasible to consider circulation control propellers for single engine aircraft or multiengine aircraft which have their propellers on a common axis (tractor pusher). The economics of the replacement requires a study for each specific airplane application.

  3. Global Observations and Understanding of the General Circulation of the Oceans

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The workshop was organized to: (1) assess the ability to obtain ocean data on a global scale that could profoundly change our understanding of the circulation; (2) identify the primary and secondary elements needed to conduct a World Ocean Circulation Experiment (WOCE); (3) if the ability is achievable, to determine what the U.S. role in such an experiment should be; and (4) outline the steps necessary to assure that an appropriate program is conducted. The consensus of the workshop was that a World Ocean Circulation Experiment appears feasible, worthwhile, and timely. Participants did agree that such a program should have the overall goal of understanding the general circulation of the global ocean well enough to be able to predict ocean response and feedback to long-term changes in the atmosphere. The overall goal, specific objectives, and recommendations for next steps in planning such an experiment are included.

  4. Interpretation of cloud-climate feedback as produced by 14 atmospheric general circulation models

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Potter, G. L.; Ghan, S. J.; Blanchet, J. P.; Boer, G. J.

    1989-01-01

    Understanding the cause of differences among general circulation model projections of carbon dioxide-induced climatic change is a necessary step toward improving the models. An intercomparison of 14 atmospheric general circulation models, for which sea surface temperature perturbations were used as a surrogate climate change, showed that there was a roughly threefold variation in global climate sensitivity. Most of this variation is attributable to differences in the models' depictions of cloud-climate feedback, a result that emphasizes the need for improvements in the treatment of clouds in these models if they are ultimately to be used as climatic predictors.

  5. Liquid and Ice Cloud Microphysics in the CSU General Circulation Model. Part II: Impact on Cloudiness, the Earth's Radiation Budget, and the General Circulation of the Atmosphere.

    NASA Astrophysics Data System (ADS)

    Fowler, Laura D.; Randall, David A.

    1996-03-01

    A prognostic equation for the mass of condensate associated with large-scale cloudiness introduces a direct coupling between the atmospheric moisture budget and the radiation budget through interactive cloud amounts and cloud optical properties. We have compared the cloudiness, the top-of-the-atmosphere and surface radiation budgets, the radiative forcing of clouds, and the atmospheric general circulation simulated with the Colorado State University general circulation model with and without such a prognostic cloud parameterization. In the EAULIQ run, the radiative effects of cloud water, cloud ice, and snow are considered; those of rain are omitted. The cloud optical depth and cloud infrared emissivity depend on the cloud water, cloud ice, and snow paths predicted by a bulk cloud microphysics parameterization. In the CONTROL run, a conventional large-scale condensation scheme is used. Cloud optical properties depend on the mean cloud temperatures. Results are presented in terms of January and July means.Comparisons with data from the International Satellite Cloud Climatology Project and the Earth Radiation Budget Experiment show that EAULIQ yields improved simulations of the geographical distributions of the simulated cloudiness, the top-of-the-atmosphere radiation budget, and the longwave and shortwave cloud radiative forcings. Differences between EAULIQ and CONTROL are largest in the Tropics and are mostly due to a decrease, in the EAULIQ run, in the amount and optical thickness of upper-tropospheric clouds. In particular, the cold bias in the outgoing longwave radiation and the overestimation of the planetary albedo obtained in the CONTROL run over the tropical convective regions are substantially reduced. Differences in the radiative and latent heating rates between EAULIQ and CONTROL lead to some improvements in the atmospheric general circulation simulated by EAULIQ when compared against statistics on the observed circulation assembled by the European Centre

  6. Subaqueous melting in Zachariae Isstrom, Northeast Greenland combining observations and an ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Cai, C.; Rignot, E. J.; Menemenlis, D.

    2015-12-01

    Zachariae Isstrom, a major ice stream in northeast Greenland, has lost its entire ice shelf in the past decade. Here, we study the evolution of subaqueous melting of its floating section during the transition. Observations show that the rate of ice shelf melting has doubled during 1999-2010 and is twice higher than that maintaining the ice shelf in a state of mass equilibrium. The ice shelf melt rate depends on the thermal forcing from warm, salty, subsurface ocean water of Atlantic origin (AW), and - in contrast with Antarctic ice shelves - on the mixing of AW with fresh buoyant subglacial discharge. Subglacial discharge has increased as result of enhanced ice sheet runoff driven by warmer air temperature; ocean thermal forcing has increased due enhanced advection of AW. Here, we employ the Massassuchetts Institute of Technology general circulation model (MITgcm) at a high spatial resolution (1 m horizontal and 1 m vertical spacing near the grounding line) to simulate the melting process in 3-D. The model is constrained by ice thickness from mass conservation, oceanic bathymetry from NASA Operation IceBridge gravity data, in-situ ocean temperature/salinity data, ocean tide height and current from the Arctic Ocean Tidal Inverse Model (AOTIM-5) and subglacial discharge from output products of the Regional Atmospheric Climate Model (RACMO). We compare the results in winter (no runoff) with summer (maximum runoff) at two different stages with (prior to 2012) and without the ice shelf (after 2012) to subaqueous melt rates deduced from remote sensing observations. We show that ice melting by the ocean has increased by one order of magnitude as a result of the transition from ice shelf terminating to near-vertical calving front terminating. We also find that subglacial discharge has a significant impact on the ice shelf melt rates in Greenland. We conclude on the impact of ocean warming and air temperature warming on the melting regime of the ice margin of Zachariae

  7. Atmospheric Diabatic Heating in Different Weather States and the General Circulation

    NASA Technical Reports Server (NTRS)

    Rossow, William B.; Zhang, Yuanchong; Tselioudis, George

    2016-01-01

    Analysis of multiple global satellite products identifies distinctive weather states of the atmosphere from the mesoscale pattern of cloud properties and quantifies the associated diabatic heating/cooling by radiative flux divergence, precipitation, and surface sensible heat flux. The results show that the forcing for the atmospheric general circulation is a very dynamic process, varying strongly at weather space-time scales, comprising relatively infrequent, strong heating events by ''stormy'' weather and more nearly continuous, weak cooling by ''fair'' weather. Such behavior undercuts the value of analyses of time-averaged energy exchanges in observations or numerical models. It is proposed that an analysis of the joint time-related variations of the global weather states and the general circulation on weather space-time scales might be used to establish useful ''feedback like'' relationships between cloud processes and the large-scale circulation.

  8. Euro3D Science Conference

    NASA Astrophysics Data System (ADS)

    Walsh, J. R.

    2004-02-01

    The Euro3D RTN is an EU funded Research Training Network to foster the exploitation of 3D spectroscopy in Europe. 3D spectroscopy is a general term for spectroscopy of an area of the sky and derives its name from its two spatial + one spectral dimensions. There are an increasing number of instruments which use integral field devices to achieve spectroscopy of an area of the sky, either using lens arrays, optical fibres or image slicers, to pack spectra of multiple pixels on the sky (``spaxels'') onto a 2D detector. On account of the large volume of data and the special methods required to reduce and analyse 3D data, there are only a few centres of expertise and these are mostly involved with instrument developments. There is a perceived lack of expertise in 3D spectroscopy spread though the astronomical community and its use in the armoury of the observational astronomer is viewed as being highly specialised. For precisely this reason the Euro3D RTN was proposed to train young researchers in this area and develop user tools to widen the experience with this particular type of data in Europe. The Euro3D RTN is coordinated by Martin M. Roth (Astrophysikalisches Institut Potsdam) and has been running since July 2002. The first Euro3D science conference was held in Cambridge, UK from 22 to 23 May 2003. The main emphasis of the conference was, in keeping with the RTN, to expose the work of the young post-docs who are funded by the RTN. In addition the team members from the eleven European institutes involved in Euro3D also presented instrumental and observational developments. The conference was organized by Andy Bunker and held at the Institute of Astronomy. There were over thirty participants and 26 talks covered the whole range of application of 3D techniques. The science ranged from Galactic planetary nebulae and globular clusters to kinematics of nearby galaxies out to objects at high redshift. Several talks were devoted to reporting recent observations with newly

  9. 3d-3d correspondence revisited

    DOE PAGES

    Chung, Hee -Joong; Dimofte, Tudor; Gukov, Sergei; ...

    2016-04-21

    In fivebrane compactifications on 3-manifolds, we point out the importance of all flat connections in the proper definition of the effective 3d N = 2 theory. The Lagrangians of some theories with the desired properties can be constructed with the help of homological knot invariants that categorify colored Jones polynomials. Higgsing the full 3d theories constructed this way recovers theories found previously by Dimofte-Gaiotto-Gukov. As a result, we also consider the cutting and gluing of 3-manifolds along smooth boundaries and the role played by all flat connections in this operation.

  10. Selected translated abstracts of Russian-language climate-change publications. 4: General circulation models

    SciTech Connect

    Burtis, M.D.; Razuvaev, V.N.; Sivachok, S.G.

    1996-10-01

    This report presents English-translated abstracts of important Russian-language literature concerning general circulation models as they relate to climate change. Into addition to the bibliographic citations and abstracts translated into English, this report presents the original citations and abstracts in Russian. Author and title indexes are included to assist the reader in locating abstracts of particular interest.

  11. Simulation of the Low-Level-Jet by general circulation models

    SciTech Connect

    Ghan, S.J.

    1996-04-01

    To what degree is the low-level jet climatology and it`s impact on clouds and precipitation being captured by current general circulation models? It is hypothesised that a need for a pramaterization exists. This paper describes this parameterization need.

  12. Documentation of the GLAS fourth order general circulation model. Volume 2: Scalar code

    NASA Technical Reports Server (NTRS)

    Kalnay, E.; Balgovind, R.; Chao, W.; Edelmann, D.; Pfaendtner, J.; Takacs, L.; Takano, K.

    1983-01-01

    Volume 2, of a 3 volume technical memoranda contains a detailed documentation of the GLAS fourth order general circulation model. Volume 2 contains the CYBER 205 scalar and vector codes of the model, list of variables, and cross references. A variable name dictionary for the scalar code, and code listings are outlined.

  13. On the design of an interactive biosphere for the GLAS general circulation model

    NASA Technical Reports Server (NTRS)

    Mintz, Y.; Sellers, P. J.; Willmott, C. J.

    1983-01-01

    Improving the realism and accuracy of the GLAS general circulation model (by adding an interactive biosphere that will simulate the transfers of latent and sensible heat from land surface to atmosphere as functions of the atmospheric conditions and the morphology and physiology of the vegetation) is proposed.

  14. Documentation of the GLAS fourth order general circulation model. Volume 1: Model documentation

    NASA Technical Reports Server (NTRS)

    Kalnay, E.; Balgovind, R.; Chao, W.; Edelmann, J.; Pfaendtner, J.; Takacs, L.; Takano, K.

    1983-01-01

    The volume 1, of a 3 volume technical memoranda which contains a documentation of the GLAS Fourth Order General Circulation Model is presented. Volume 1 contains the documentation, description of the stratospheric/tropospheric extension, user's guide, climatological boundary data, and some climate simulation studies.

  15. Uncertainties in Carbon Dioxide Radiative Forcing in Atmospheric General Circulation Models

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Zhang, M.-H.; Potter, G. L.; Gates, W. L.; Taylor, K. E.; Barker, H. W.; Colman, R. A.; Fraser, J. R.; McAvaney, B. J.; Dazlich, D. A.; Randall, D. A.; DelGenio, A. D.; Lacis, A. A.; Esch, M.; Roeckner, E.; Galin, V.; Hack, J. J.; Kiehl, J. T.; Ingram, W. J.; LeTreut, H.

    1993-01-01

    Global warming, caused by an increase in the concentrations of greenhouse gases, is the direct result of greenhouse gas-induced radiative forcing. When a doubling of atmospheric carbon dioxide is considered, this forcing differed substantially among 15 atmospheric general circulation models. Although there are several potential causes, the largest contributor was the carbon dioxide radiation parameterizations of the models.

  16. Impact of variations of gravitational acceleration on the general circulation of the planetary atmosphere

    NASA Astrophysics Data System (ADS)

    Kilic, Cevahir; Raible, Christoph C.; Stocker, Thomas F.; Kirk, Edilbert

    2017-01-01

    Fundamental to the redistribution of energy in a planetary atmosphere is the general circulation and its meridional structure. We use a general circulation model of the atmosphere in an aquaplanet configuration with prescribed sea surface temperature and investigate the influence of the gravitational acceleration g on the structure of the circulation. For g =g0 = 9.81 ms-2 , three meridional cells exist in each hemisphere. Up to about g /g0 = 1.4 all cells increase in strength. Further increasing this ratio results in a weakening of the thermally indirect cell, such that a two- and finally a one-cell structure of the meridional circulation develops in each hemisphere. This transition is explained by the primary driver of the thermally direct Hadley cell: the diabatic heating at the equator which is proportional to g. The analysis of the energetics of the atmospheric circulation based on the Lorenz energy cycle supports this finding. For Earth-like gravitational accelerations transient eddies are primarily responsible for the meridional heat flux. For large gravitational accelerations, the direct zonal mean conversion of energy dominates the meridional heat flux.

  17. PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITHOUT TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. The Apollo implementation of PLOT3D uses some of the capabilities of

  18. PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITH TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. The Apollo implementation of PLOT3D uses some of the capabilities of

  19. Variability patterns of the general circulation and sea water temperature in the North Sea

    NASA Astrophysics Data System (ADS)

    Mathis, M.; Elizalde, A.; Mikolajewicz, U.; Pohlmann, T.

    2015-06-01

    This study investigates patterns of spatio-temporal variability in the North Sea and their major driving mechanisms. Leading variability modes of the general circulation and sea water temperature are extracted from model results by means of Empirical Orthogonal Functions (EOF) analysis. The model results originate from an uncoupled simulation with the global ocean model MPIOM, forced with ERA40 reanalysis data at the air-sea interface. For this regional model study, MPIOM has been run with a stretched grid configuration enabling higher horizontal resolution in the Northwest European Shelf and North Atlantic ocean. The analysis is applied to interannual variabilities of winter and summer separately. The results indicate that on seasonal scales the leading variability mode of the general circulation affects the entire North Sea, accompanied by significant inflow anomalies through the Fair-Isle Passage. Correlations of the corresponding Principal Component (PC) with wind density functions reveal the circulation anomalies to coincide with westerly and south-westerly wind anomalies. The second mode describes circulation anomalies along the Norwegian Trench and English Channel, which correlate with north-westerly wind anomalies caused by variations in large-scale atmospheric pressure areas centered over the British Isles. For sea water temperature, distinct variability patterns are induced by variable surface heat fluxes, vertical mixing, and variable advective heat fluxes. The first mode of both the general circulation and water temperature in winter mainly represents the response to atmospheric variations in the North Atlantic Oscillation (NAO). However, the higher modes account for such variabilities that cannot be explained by the NAO. As a consequence of the integrated effects of the different variability modes on the circulation system and heat content, local correlations of the NAO with volume transports and water temperature are weakened in the regions of

  20. General design method for 3-dimensional, potential flow fields. Part 2: Computer program DIN3D1 for simple, unbranched ducts

    NASA Technical Reports Server (NTRS)

    Stanitz, J. D.

    1985-01-01

    The general design method for three-dimensional, potential, incompressible or subsonic-compressible flow developed in part 1 of this report is applied to the design of simple, unbranched ducts. A computer program, DIN3D1, is developed and five numerical examples are presented: a nozzle, two elbows, an S-duct, and the preliminary design of a side inlet for turbomachines. The two major inputs to the program are the upstream boundary shape and the lateral velocity distribution on the duct wall. As a result of these inputs, boundary conditions are overprescribed and the problem is ill posed. However, it appears that there are degrees of compatibility between these two major inputs and that, for reasonably compatible inputs, satisfactory solutions can be obtained. By not prescribing the shape of the upstream boundary, the problem presumably becomes well posed, but it is not clear how to formulate a practical design method under this circumstance. Nor does it appear desirable, because the designer usually needs to retain control over the upstream (or downstream) boundary shape. The problem is further complicated by the fact that, unlike the two-dimensional case, and irrespective of the upstream boundary shape, some prescribed lateral velocity distributions do not have proper solutions.

  1. Performance and accuracy of criticality calculations performed using WARP – A framework for continuous energy Monte Carlo neutron transport in general 3D geometries on GPUs

    DOE PAGES

    Bergmann, Ryan M.; Rowland, Kelly L.; Radnović, Nikola; ...

    2017-05-01

    In this companion paper to "Algorithmic Choices in WARP - A Framework for Continuous Energy Monte Carlo Neutron Transport in General 3D Geometries on GPUs" (doi:10.1016/j.anucene.2014.10.039), the WARP Monte Carlo neutron transport framework for graphics processing units (GPUs) is benchmarked against production-level central processing unit (CPU) Monte Carlo neutron transport codes for both performance and accuracy. We compare neutron flux spectra, multiplication factors, runtimes, speedup factors, and costs of various GPU and CPU platforms running either WARP, Serpent 2.1.24, or MCNP 6.1. WARP compares well with the results of the production-level codes, and it is shown that on the newestmore » hardware considered, GPU platforms running WARP are between 0.8 to 7.6 times as fast as CPU platforms running production codes. Also, the GPU platforms running WARP were between 15% and 50% as expensive to purchase and between 80% to 90% as expensive to operate as equivalent CPU platforms performing at an equal simulation rate.« less

  2. The Early Jurassic climate: General circulation model simulations and the paleoclimate record

    SciTech Connect

    Chandler, M.A.

    1992-01-01

    This thesis presents the results of several general circulation model simulations of the Early Jurassic climate. The general circulation model employed was developed at the Goddard Institute for Space Studies while most paleoclimate data were provided by the Paleographic Atlas Project of the University of Chicago. The first chapter presents an Early Jurassic base simulation, which uses detailed reconstructions of paleogeography, vegetation, and sea surface temperature as boundary condition data sets. The resulting climatology reveals an Earth 5.2[degrees]C warmer, globally, than at present and a latitudinal temperature gradient dominated by high-latitude warming (+20[degrees]C) and little tropical change (+1[degrees]C). Comparisons show a good correlation between simulated results and paleoclimate data. Sensitivity experiments are used to investigate any model-data mismatches. Chapters two and three discuss two important aspects of Early Jurassic climate, continental aridity and global warming. Chapter two focuses on the hydrological capabilities of the general circulation model. The general circulation model's hydrologic diagnostics are evaluated, using the distribution of modern deserts and Early Jurassic paleoclimate data as validating constraints. A new method, based on general circulation model diagnostics and empirical formulae, is proposed for evaluating moisture balance. Chapter three investigates the cause of past global warming, concentrating on the role of increased ocean heat transport. Early Jurassic simulations show that increased ocean heat transports may have been a major factor in past climates. Increased ocean heat transports create latitudinal temperature gradients that closely approximate paleoclimate data and solve the problem of tropical overheating that results from elevated atmospheric carbon dioxide. Increased carbon dioxide cannot duplicate the Jurassic climate without also including increased ocean heat transports.

  3. Venus mesosphere and thermosphere. III. Three-dimensional general circulation with coupled dynamics and composition

    SciTech Connect

    Bougher, S.W.; Roble, R.G.E.; Dickinson, R.E.; Ridley, E.C.

    1988-03-01

    The three-dimensional structure and circulation of Venus' upper mesosphere and thermosphere is examined by means of a modification of NCAR's earth thermosphere general circulation model, using the parameterizations from an earlier two-dimensional Venus model that included eddy diffusion and wave drag. Many of the observed Venus thermosphere features are found to be reproduced by the model, which thereby serves as a benchmark on which to incorporate additional minor constituents and test new self-consistent parameterizations for wave drag and superrotation. 36 references.

  4. The Numerical Studies Program for the Atmospheric General Circulation Experiment (AGCE) for Spacelab Flights

    NASA Technical Reports Server (NTRS)

    Fowlis, W. W. (Editor); Davis, M. H. (Editor)

    1981-01-01

    The atmospheric general circulation experiment (AGCE) numerical design for Spacelab flights was studied. A spherical baroclinic flow experiment which models the large scale circulations of the Earth's atmosphere was proposed. Gravity is simulated by a radial dielectric body force. The major objective of the AGCE is to study nonlinear baroclinic wave flows in spherical geometry. Numerical models must be developed which accurately predict the basic axisymmetric states and the stability of nonlinear baroclinic wave flows. A three dimensional, fully nonlinear, numerical model and the AGCE based on the complete set of equations is required. Progress in the AGCE numerical design studies program is reported.

  5. Autofocus for 3D imaging

    NASA Astrophysics Data System (ADS)

    Lee-Elkin, Forest

    2008-04-01

    Three dimensional (3D) autofocus remains a significant challenge for the development of practical 3D multipass radar imaging. The current 2D radar autofocus methods are not readily extendable across sensor passes. We propose a general framework that allows a class of data adaptive solutions for 3D auto-focus across passes with minimal constraints on the scene contents. The key enabling assumption is that portions of the scene are sparse in elevation which reduces the number of free variables and results in a system that is simultaneously solved for scatterer heights and autofocus parameters. The proposed method extends 2-pass interferometric synthetic aperture radar (IFSAR) methods to an arbitrary number of passes allowing the consideration of scattering from multiple height locations. A specific case from the proposed autofocus framework is solved and demonstrates autofocus and coherent multipass 3D estimation across the 8 passes of the "Gotcha Volumetric SAR Data Set" X-Band radar data.

  6. Observations and Modeling of the Transient General Circulation of the North Pacific Basin

    NASA Technical Reports Server (NTRS)

    McWilliams, James C.

    2000-01-01

    Because of recent progress in satellite altimetry and numerical modeling and the accumulation and archiving of long records of hydrographic and meteorological variables, it is becoming feasible to describe and understand the transient general circulation of the ocean (i.e., variations with spatial scales larger than a few hundred kilometers and time scales of seasonal and longer-beyond the mesoscale). We have carried out various studies in investigation of the transient general circulation of the Pacific Ocean from a coordinated analysis of satellite altimeter data, historical hydrographic gauge data, scatterometer wind observations, reanalyzed operational wind fields, and a variety of ocean circulation models. Broadly stated, our goal was to achieve a phenomenological catalogue of different possible types of large-scale, low-frequency variability, as a context for understanding the observational record. The approach is to identify the simplest possible model from which particular observed phenomena can be isolated and understood dynamically and then to determine how well these dynamical processes are represented in more complex Oceanic General Circulation Models (OGCMs). Research results have been obtained on Rossby wave propagation and transformation, oceanic intrinsic low-frequency variability, effects of surface gravity waves, pacific data analyses, OGCM formulation and developments, and OGCM simulations of forced variability.

  7. 3D and Education

    NASA Astrophysics Data System (ADS)

    Meulien Ohlmann, Odile

    2013-02-01

    Today the industry offers a chain of 3D products. Learning to "read" and to "create in 3D" becomes an issue of education of primary importance. 25 years professional experience in France, the United States and Germany, Odile Meulien set up a personal method of initiation to 3D creation that entails the spatial/temporal experience of the holographic visual. She will present some different tools and techniques used for this learning, their advantages and disadvantages, programs and issues of educational policies, constraints and expectations related to the development of new techniques for 3D imaging. Although the creation of display holograms is very much reduced compared to the creation of the 90ies, the holographic concept is spreading in all scientific, social, and artistic activities of our present time. She will also raise many questions: What means 3D? Is it communication? Is it perception? How the seeing and none seeing is interferes? What else has to be taken in consideration to communicate in 3D? How to handle the non visible relations of moving objects with subjects? Does this transform our model of exchange with others? What kind of interaction this has with our everyday life? Then come more practical questions: How to learn creating 3D visualization, to learn 3D grammar, 3D language, 3D thinking? What for? At what level? In which matter? for whom?

  8. The puzzling Venusian polar atmospheric structure reproduced by a general circulation model

    PubMed Central

    Ando, Hiroki; Sugimoto, Norihiko; Takagi, Masahiro; Kashimura, Hiroki; Imamura, Takeshi; Matsuda, Yoshihisa

    2016-01-01

    Unlike the polar vortices observed in the Earth, Mars and Titan atmospheres, the observed Venus polar vortex is warmer than the midlatitudes at cloud-top levels (∼65 km). This warm polar vortex is zonally surrounded by a cold latitude band located at ∼60° latitude, which is a unique feature called ‘cold collar' in the Venus atmosphere. Although these structures have been observed in numerous previous observations, the formation mechanism is still unknown. Here we perform numerical simulations of the Venus atmospheric circulation using a general circulation model, and succeed in reproducing these puzzling features in close agreement with the observations. The cold collar and warm polar region are attributed to the residual mean meridional circulation enhanced by the thermal tide. The present results strongly suggest that the thermal tide is crucial for the structure of the Venus upper polar atmosphere at and above cloud levels. PMID:26832195

  9. Regional climates in the GISS general circulation model: Surface air temperature

    NASA Technical Reports Server (NTRS)

    Hewitson, Bruce

    1994-01-01

    One of the more viable research techniques into global climate change for the purpose of understanding the consequent environmental impacts is based on the use of general circulation models (GCMs). However, GCMs are currently unable to reliably predict the regional climate change resulting from global warming, and it is at the regional scale that predictions are required for understanding human and environmental responses. Regional climates in the extratropics are in large part governed by the synoptic-scale circulation and the feasibility of using this interscale relationship is explored to provide a way of moving to grid cell and sub-grid cell scales in the model. The relationships between the daily circulation systems and surface air temperature for points across the continental United States are first developed in a quantitative form using a multivariate index based on principal components analysis (PCA) of the surface circulation. These relationships are then validated by predicting daily temperature using observed circulation and comparing the predicted values with the observed temperatures. The relationships predict surface temperature accurately over the major portion of the country in winter, and for half the country in summer. These relationships are then applied to the surface synoptic circulation of the Goddard Institute for Space Studies (GISS) GCM control run, and a set of surface grid cell temperatures are generated. These temperatures, based on the larger-scale validated circulation, may now be used with greater confidence at the regional scale. The generated temperatures are compared to those of the model and show that the model has regional errors of up to 10 C in individual grid cells.

  10. Using the Flow-3D General Moving Object Model to Simulate Coupled Liquid Slosh - Container Dynamics on the SPHERES Slosh Experiment: Aboard the International Space Station

    NASA Technical Reports Server (NTRS)

    Schulman, Richard; Kirk, Daniel; Marsell, Brandon; Roth, Jacob; Schallhorn, Paul

    2013-01-01

    The SPHERES Slosh Experiment (SSE) is a free floating experimental platform developed for the acquisition of long duration liquid slosh data aboard the International Space Station (ISS). The data sets collected will be used to benchmark numerical models to aid in the design of rocket and spacecraft propulsion systems. Utilizing two SPHERES Satellites, the experiment will be moved through different maneuvers designed to induce liquid slosh in the experiment's internal tank. The SSE has a total of twenty-four thrusters to move the experiment. In order to design slosh generating maneuvers, a parametric study with three maneuvers types was conducted using the General Moving Object (GMO) model in Flow-30. The three types of maneuvers are a translation maneuver, a rotation maneuver and a combined rotation translation maneuver. The effectiveness of each maneuver to generate slosh is determined by the deviation of the experiment's trajectory as compared to a dry mass trajectory. To fully capture the effect of liquid re-distribution on experiment trajectory, each thruster is modeled as an independent force point in the Flow-3D simulation. This is accomplished by modifying the total number of independent forces in the GMO model from the standard five to twenty-four. Results demonstrate that the most effective slosh generating maneuvers for all motions occurs when SSE thrusters are producing the highest changes in SSE acceleration. The results also demonstrate that several centimeters of trajectory deviation between the dry and slosh cases occur during the maneuvers; while these deviations seem small, they are measureable by SSE instrumentation.

  11. Protocol for a process evaluation of a cluster randomised controlled trial to improve management of multimorbidity in general practice: the 3D study

    PubMed Central

    Shaw, Alison; Guthrie, Bruce; Wye, Lesley; Brookes, Sara; Bower, Peter; Mercer, Stewart

    2016-01-01

    Introduction As an increasing number of people are living with more than 1 long-term condition, identifying effective interventions for the management of multimorbidity in primary care has become a matter of urgency. Interventions are challenging to evaluate due to intervention complexity and the need for adaptability to different contexts. A process evaluation can provide extra information necessary for interpreting trial results and making decisions about whether the intervention is likely to be successful in a wider context. The 3D (dimensions of health, drugs and depression) study will recruit 32 UK general practices to a cluster randomised controlled trial to evaluate effectiveness of a patient-centred intervention. Practices will be randomised to intervention or usual care. Methods and analysis The aim of the process evaluation is to understand how and why the intervention was effective or ineffective and the effect of context. As part of the intervention, quantitative data will be collected to provide implementation feedback to all intervention practices and will contribute to evaluation of implementation fidelity, alongside case study data. Data will be collected at the beginning and end of the trial to characterise each practice and how it provides care to patients with multimorbidity. Mixed methods will be used to collect qualitative data from 4 case study practices, purposively sampled from among intervention practices. Qualitative data will be analysed using techniques of constant comparison to develop codes integrated within a flexible framework of themes. Quantitative and qualitative data will be integrated to describe case study sites and develop possible explanations for implementation variation. Analysis will take place prior to knowing trial outcomes. Ethics and dissemination Study approved by South West (Frenchay) National Health Service (NHS) Research Ethics Committee (14/SW/0011). Findings will be disseminated via a final report, peer

  12. 3D Imaging.

    ERIC Educational Resources Information Center

    Hastings, S. K.

    2002-01-01

    Discusses 3 D imaging as it relates to digital representations in virtual library collections. Highlights include X-ray computed tomography (X-ray CT); the National Science Foundation (NSF) Digital Library Initiatives; output peripherals; image retrieval systems, including metadata; and applications of 3 D imaging for libraries and museums. (LRW)

  13. Global coupled ocean-atmosphere general circulation models in LASG/IAP

    NASA Astrophysics Data System (ADS)

    Yongqiang, Yu; Xuehong, Zhang; Yufu, Guo

    2004-06-01

    Coupled ocean-atmospheric general circulation models are the only tools to quantitatively simulate the climate system. Since the end of the 1980s, a group of scientists in the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences (CAS), have been working to develop a global OGCM and a global coupled ocean-atmosphere general circulation model (CGCM). From the original flux anomaly-coupling model developed in the beginning of the 1990s to the latest directly-coupling model, LASG scientists have developed four global coupled GCMs. This study summarizes the development history of these models and describes the third and fourth coupled GCMs and selected applications. Strengths and weaknesses of these models are highlighted.

  14. Energetics analysis of the observed and simulated general circulation using three-dimensional normal mode expansions

    NASA Technical Reports Server (NTRS)

    Tanaka, Hiroshi; Kung, Ernest C.; Baker, Wayman E.

    1986-01-01

    The energetics characteristics of the observed and simulated general circulation are analyzed using three-dimensional normal mode expansions. The data sets involved are the Goddard Laboratory for Atmospheres (GLA) analysis and simulation data and the Geophysical Fluid Dynamics Laboratory (GFDL) analysis data. The spectral energy properties of the Rossby and gravity modes and energy transformations are presented. Significant influences of model characteristics and the assimilation techniques are observed in the barotropic energy spectrum, particularly for the gravity mode. Energy transformations of the zonal mean field in the GLA analysis and simulation are similar, but distinctly different from that in the GFDL analysis. However, overall, the energy generation in the baroclinic mode is largely balanced by the sink in the barotropic mode. The present study may demonstrate utilities of the three-dimensional normal mode energetics in the analysis of the general circulation.

  15. The influence of the tropics upon the prediction of the Southern Hemisphere circulation within the GLAS GCM. [Goddard Laboratory for Atmospheric Sciences General Circulation Model

    NASA Technical Reports Server (NTRS)

    Baker, W. E.; Paegle, J.

    1983-01-01

    An examination is undertaken of the sensitivity of short term Southern Hemisphere circulation prediction to tropical wind data and tropical latent heat release. The data assimilation experiments employ the Goddard Laboratory for Atmospheric Sciences' fourth-order general circulation model. Two of the experiments are identical, but for the fact that one uses tropical wind data while the other does not. A third experiment contains the identical initial conditions of forecasts with tropical winds, while suppressing tropical latent heat release.

  16. Global OH distribution derived from general circulation model fields of ozone and water vapor

    SciTech Connect

    Allam, R.J.; Groves, K.S.; Tuck, A.F.

    1981-06-20

    The variability of OH computed with a photochemical steady state model from general circulation model fields of ozone and water vapor is examined. Multivariate regression analysis is used to obtain values of parametric coefficients for the variables upon which the OH field principally depends, and conclusions are drawn about the longitudinal phase relations between these variables for various pressure levels. 21 references, 8 figures, 6 tables.

  17. Use of Ocean Remote Sensing Data to Enhance Predictions with a Coupled General Circulation Model

    NASA Technical Reports Server (NTRS)

    Rienecker, Michele M.

    1999-01-01

    Surface height, sea surface temperature and surface wind observations from satellites have given a detailed time sequence of the initiation and evolution of the 1997/98 El Nino. The data have beet complementary to the subsurface TAO moored data in their spatial resolution and extent. The impact of satellite observations on seasonal prediction in the tropical Pacific using a coupled ocean-atmosphere general circulation model will be presented.

  18. Derivation of revised formulae for eddy viscous forces used in the ocean general circulation model

    NASA Technical Reports Server (NTRS)

    Chou, Ru Ling

    1988-01-01

    Presented is a re-derivation of the eddy viscous dissipation tensor commonly used in present oceanographic general circulation models. When isotropy is imposed, the currently-used form of the tensor fails to return to the laplacian operator. In this paper, the source of this error is identified in a consistent derivation of the tensor in both rectangular and earth spherical coordinates, and the correct form of the eddy viscous tensor is presented.

  19. Stratospheric wind errors, initial states and forecast skill in the GLAS general circulation model

    NASA Technical Reports Server (NTRS)

    Tenenbaum, J.

    1983-01-01

    Relations between stratospheric wind errors, initial states and 500 mb skill are investigated using the GLAS general circulation model initialized with FGGE data. Erroneous stratospheric winds are seen in all current general circulation models, appearing also as weak shear above the subtropical jet and as cold polar stratospheres. In this study it is shown that the more anticyclonic large-scale flows are correlated with large forecast stratospheric winds. In addition, it is found that for North America the resulting errors are correlated with initial state jet stream accelerations while for East Asia the forecast winds are correlated with initial state jet strength. Using 500 mb skill scores over Europe at day 5 to measure forecast performance, it is found that both poor forecast skill and excessive stratospheric winds are correlated with more anticyclonic large-scale flows over North America. It is hypothesized that the resulting erroneous kinetic energy contributes to the poor forecast skill, and that the problem is caused by a failure in the modeling of the stratospheric energy cycle in current general circulation models independent of vertical resolution.

  20. The Impact of Soil Moisture Anomalies on the General Circulation: A Comprehensive Analysis over North America

    NASA Astrophysics Data System (ADS)

    Koster, R. D.; Chang, Y.; Wang, H.; Schubert, S. D.

    2014-12-01

    Recent work (Koster et al., 2014) has demonstrated the potential for a soil moisture anomaly to influence the general circulation (as characterized by the meridional wind at 250 mb) and to influence thereby the surface meteorological conditions in remote locations, even a thousand kilometers away. An in-depth look at this phenomenon is now afforded by a more comprehensive set of AGCM ensemble experiments. Each experiment is designed to quantify the impact of a specific local dry soil moisture anomaly, prescribed somewhere in North America, on the general circulation. The locations tested in the different experiments span much of the continent, allowing a comprehensive picture of the circulation's sensitivity to soil moisture anomalies. The main result is that while the sensitivity does vary with the imposed anomaly's geographical location, a dry anomaly in general tends to induce, just to the east, a northerly flow at 250 mb, with (at times) consequent impacts on surface meteorological variables. These results tend to be supported by reanalysis data. Koster, R. D., Y. Chang, and S. D. Schubert, 2014: A mechanism for land-atmosphere feedback involving planetary wave structures. J. Climate, 27, 9290-9301.

  1. The Impact of Soil Moisture Anomalies on the General Circulation: A Comprehensive Analysis over North America

    NASA Astrophysics Data System (ADS)

    Koster, R. D.; Chang, Y.; Wang, H.; Schubert, S. D.

    2015-12-01

    Recent work (Koster et al., 2014) has demonstrated the potential for a soil moisture anomaly to influence the general circulation (as characterized by the meridional wind at 250 mb) and to influence thereby the surface meteorological conditions in remote locations, even a thousand kilometers away. An in-depth look at this phenomenon is now afforded by a more comprehensive set of AGCM ensemble experiments. Each experiment is designed to quantify the impact of a specific local dry soil moisture anomaly, prescribed somewhere in North America, on the general circulation. The locations tested in the different experiments span much of the continent, allowing a comprehensive picture of the circulation's sensitivity to soil moisture anomalies. The main result is that while the sensitivity does vary with the imposed anomaly's geographical location, a dry anomaly in general tends to induce, just to the east, a northerly flow at 250 mb, with (at times) consequent impacts on surface meteorological variables. These results tend to be supported by reanalysis data. Koster, R. D., Y. Chang, and S. D. Schubert, 2014: A mechanism for land-atmosphere feedback involving planetary wave structures. J. Climate, 27, 9290-9301.

  2. 3D Computations and Experiments

    SciTech Connect

    Couch, R; Faux, D; Goto, D; Nikkel, D

    2004-04-05

    This project consists of two activities. Task A, Simulations and Measurements, combines all the material model development and associated numerical work with the materials-oriented experimental activities. The goal of this effort is to provide an improved understanding of dynamic material properties and to provide accurate numerical representations of those properties for use in analysis codes. Task B, ALE3D Development, involves general development activities in the ALE3D code with the focus of improving simulation capabilities for problems of mutual interest to DoD and DOE. Emphasis is on problems involving multi-phase flow, blast loading of structures and system safety/vulnerability studies.

  3. RETICULOENDOTHELIAL CLEARANCE OF CIRCULATING FIBRIN IN THE PATHOGENESIS OF THE GENERALIZED SHWARTZMAN REACTION

    PubMed Central

    Lee, Leung

    1962-01-01

    Intravenous injections of endotoxin or infusions of thrombin in the rabbit initiate intravascular coagulation but do not usually result in massive deposition of fibrin. It has been proposed that the reticuloendothelial system may function efficiently in the removal of circulating fibrin; its blockade permits reproduction of all of the features of the generalized Shwartzman reaction by infusions of thrombin. In the rabbit the reticuloendothelial system may constitute the major protective mechanism against the vasculo-occlusive lesions of the generalized Shwartzman reaction, which appears to be the direct consequence of intravascular fibrin formation and deposition. PMID:14463528

  4. Results of various studies made with the NCAR Thermospheric General Circulation Model (TGCM) (invited review)

    NASA Technical Reports Server (NTRS)

    Roble, R. G.

    1986-01-01

    The NCAR thermospheric general circulation model (TGCM) has been used for a variety of thermospheric dynamic studies. It has also been used to compare model predictions with measurements made from various ground-based Fabry-Perot interferometer stations, incoherent scatter radar stations and the Dynamics Explorer satellites. The various input and output features of the model are described. These include the specification of solar EUV fluxes, and descriptions of empirical models to specify auroral particle precipitation, ion drag, and magnetospheric convection. Results are presented for solstice conditions giving the model perturbation temperature and circulation response to solar heating forcing alone and also with the inclusion of magnetospheric convections for two different dawn-dusk potential drops, 20 and 60 kV respectively. Results at two constant pressure levels Z =+1 at 300 km and Z= -4 at 120 km are presented for both the winter and summer polar cap regions. The circulation over the Northern Hemisphere polar cap in both the upper and lower thermosphere are presented along with a figure showing that the circulation is mainly a non-divergent irrotational flow responding to ion drag. The results of a study made on the Southern Hemisphere polar cap during October 1981 where Dynamics Explorer satellite measurements of winds, temperature and composition are compared to TGCM predictions are also presented. A diagnostic package that has been developed to analyze the balance of forces operating in the TGCM is presented next illustrating that in the F-region ion drag and pressure provide the main force balance and in the E-region ion drag, pressure and the coriolis forces provide the main balance. The TGCM prediction for the June 10, 1983 total solar eclipse are next presented showing a thermospheric disturbance following the path of totality. Finally, results are presented giving the global circulation, temperature and composition structure of the thermosphere for

  5. High Altitude Dust Layers on Mars: Observations and Impact on the General Circulation

    NASA Astrophysics Data System (ADS)

    Guzewich, S. D.; Talaat, E. R.; Toigo, A. D.; Waugh, D. W.; McConnochie, T. H.

    2012-12-01

    Limb-scanning observations of dust mixing ratio with the Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor spanning three Mars years (MY 24-27) show two discrete layers of enhanced dust mixing ratios at 20-30 km and 45-65 km. This represents a significant departure from the canonical Conrath-ν (Conrath, 1975) vertical dust profile used in most Mars general circulation models (GCMs). The lower layer was previously identified with the Mars Climate Sounder (Heavens et al., 2011) and is primarily a tropical phenomenon. It is persistent year-round, save a brief period each year from Ls = 20°-50°, reaches highest altitudes and amplitudes during the dust storm season, and exhibits significant diurnal variability associated with water ice clouds. The 45-65 km layer is nearly absent in nighttime observations, reaches highest amplitudes during northern summer, and is not observed during the dust storm season. The TES dust climatology was adapted to radiatively force the MarsWRF GCM and simulations were performed to investigate the effect of the new dust profiles. Changes in the vertical profile of dust result in significant changes to the general circulation of the atmosphere including an enhanced polar warming, decoupled middle and lower atmosphere meridional circulations, and an improved match to TES temperature observations.

  6. Hierarchical framework for coupling a biogeochemical trace gas model to a general circulation model

    SciTech Connect

    Miller, N.L.; Foster, I.T.

    1994-04-01

    A scheme is described for the computation of terrestrial biogeochemical trace gas fluxes in the context of a general circulation model. This hierarchical system flux scheme (HSFS) incorporates five major components: (1) a general circulation model (GCM), which provides a medium-resolution (i.e., 1{degrees} by 1{degrees}) simulation of the atmospheric circulation; (2) a procedure for identifying regions of defined homogeneity of surface type within GCM grid cells; (3) a set of surface process models, to be run within each homogeneous region, which include a biophysical model, the Biosphere Atmospheric Transfer Scheme (BATS), and a biogeochemical model (BGCM); (4) an interpolation/integration system that transfers information between the GCM and surface process models with finer resolution; and (5) an interactive data array based on a geographic information system (GIS), which provides land characteristic information via the interpolator. The goals of this detailed investigation are to compute the local and global sensitivities of trace gas fluxes to GCM and BATS variables, the effects of trace gas fluxes on global climate, and the effects of global climate on specific biomes.

  7. AE3D

    SciTech Connect

    Spong, Donald A

    2016-06-20

    AE3D solves for the shear Alfven eigenmodes and eigenfrequencies in a torodal magnetic fusion confinement device. The configuration can be either 2D (e.g. tokamak, reversed field pinch) or 3D (e.g. stellarator, helical reversed field pinch, tokamak with ripple). The equations solved are based on a reduced MHD model and sound wave coupling effects are not currently included.

  8. A simple biosphere model (SiB) for use within general circulation models

    NASA Technical Reports Server (NTRS)

    Sellers, P. J.; Mintz, Y.; Sud, Y. C.; Dalcher, A.

    1986-01-01

    A simple realistic biosphere model for calculating the transfer of energy, mass and momentum between the atmosphere and the vegetated surface of the earth has been developed for use in atmospheric general circulation models. The vegetation in each terrestrial model grid is represented by an upper level, representing the perennial canopy of trees and shrubs, and a lower level, representing the annual cover of grasses and other heraceous species. The vegetation morphology and the physical and physiological properties of the vegetation layers determine such properties as: the reflection, transmission, absorption and emission of direct and diffuse radiation; the infiltration, drainage, and storage of the residual rainfall in the soil; and the control over the stomatal functioning. The model, with prescribed vegetation parameters and soil interactive soil moisture, can be used for prediction of the atmospheric circulation and precipitaion fields for short periods of up to a few weeks.

  9. Intraseasonal eddies in the Sulawesi Sea simulated in an ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Masumoto, Y.; Kagimoto, T.; Yoshida, M.; Fukuda, M.; Hirose, N.; Yamagata, T.

    The intraseasonal variability associated with mesoscale eddies in the Sulawesi Sea simulated in a high resolution ocean general circulation model is described in detail. The cyclonic eddies, with a diameter of about 400 km, are generated at the entrance of the Sulawesi Sea between the Mindanao and the Halmahera Islands with 40 days interval. They are associated with a high speed (> 20 cm/s) down to 1000 m level. The anticlockwise circulation in the Sulawesi Sea, reported so far in both models and observations, may be a long time-averaged image of the above energetic eddies. The intraseasonal eddies significantly affect the volume transport through passages in the northern part of the Indonesian archipelago. The intraseasonal transport variation, however, is highly damped within the Indonesian seas in the present model.

  10. Vertical heat flux in the ocean: Estimates from observations and from a coupled general circulation model

    NASA Astrophysics Data System (ADS)

    Cummins, Patrick F.; Masson, Diane; Saenko, Oleg A.

    2016-06-01

    The net heat uptake by the ocean in a changing climate involves small imbalances between the advective and diffusive processes that transport heat vertically. Generally, it is necessary to rely on global climate models to study these processes in detail. In the present study, it is shown that a key component of the vertical heat flux, namely that associated with the large-scale mean vertical circulation, can be diagnosed over extra-tropical regions from global observational data sets. This component is estimated based on the vertical velocity obtained from the geostrophic vorticity balance, combined with estimates of absolute geostrophic flow. Results are compared with the output of a non-eddy resolving, coupled atmosphere-ocean general circulation model. Reasonable agreement is found in the latitudinal distribution of the vertical heat flux, as well as in the area-integrated flux below about 250 m depth. The correspondence with the coupled model deteriorates sharply at depths shallower than 250 m due to the omission of equatorial regions from the calculation. The vertical heat flux due to the mean circulation is found to be dominated globally by the downward contribution from the Southern Hemisphere, in particular the Southern Ocean. This is driven by the Ekman vertical velocity which induces an upward transport of seawater that is cold relative to the horizontal average at a given depth. The results indicate that the dominant characteristics of the vertical transport of heat due to the mean circulation can be inferred from simple linear vorticity dynamics over much of the ocean.

  11. Multi-Stencil Streamline Fast Marching: A General 3-D Framework to Determine Myocardial Thickness and Transmurality in Late Enhancement Images.

    PubMed

    Merino-Caviedes, Susana; Cordero-Grande, Lucilio; Revilla-Orodea, Ana; Sevilla-Ruiz, Teresa; Pérez, M Teresa; Martín-Fernández, Marcos; Alberola-López, Carlos

    2014-01-01

    We propose a fully 3-D methodology for the computation of myocardial nonviable tissue transmurality in contrast enhanced magnetic resonance images. The outcome is a continuous map defined within the myocardium where not only current state-of-the-art measures of transmurality can be calculated, but also information on the location of nonviable tissue is preserved. The computation is done by means of a partial differential equation framework we have called multi-stencil streamline fast marching. Using it, the myocardial and scarred tissue thickness is simultaneously computed. Experimental results show that the proposed 3-D method allows for the computation of transmurality in myocardial regions where current 2-D methods are not able to as conceived, and it also provides more robust and accurate results in situations where the assumptions on which current 2-D methods are based-i.e., there is a visible endocardial contour and its corresponding epicardial points lie on the same slice-, are not met.

  12. Moisture and wave-mean flow interactions in the general circulation of Earth's atmosphere

    NASA Astrophysics Data System (ADS)

    Yamada, Ray

    Baroclinic eddies play an important role in shaping the midlatitude climate and its variability. They are the dominant means by which heat, momentum, and water vapor are transported in the atmosphere, but their turbulent nature makes it challenging to grasp their aggregate effect on the mean circulation. Wave-mean flow diagnostics provide an effective means for understanding the interactions between eddies and the mean circulation. These diagnostics are derived by dynamically motivated averaging of the equations of motion, which exposes the total explicit eddy effect on the mean circulation tendency. Most of the classic formulations of these diagnostics have been limited by the fact that they do not account for the eddy flux of water vapor, which can drive circulation through latent heat released from condensation. In the first part of this thesis, a moist isentropic generalization of the Eliassen-Palm (EP) flux diagnostic is developed. Moist isentropes are often not invertible with height, which prevents the standard techniques used to derive the dry diagnostic from being applied in the moist case. This issue is resolved by using a conditional-averaging approach to define a weak coordinate transformation. The primitive equations, EP flux, and EP theorem are derived in generality for non- invertible coordinates, without assumptions of quasi-geostrophy or small wave-amplitude. It is shown that, in the reanalysis climatology, the moist EP flux is twice as strong as the dry EP flux and has a greater equatorward extent. Physically, the increase in momentum exchange is tied to an enhancement of the form drag associated with the horizontal structure of midlatitude eddies, where the poleward flow of moist air is located in regions of strong eastward pressure gradients. The second part of this thesis studies the effect of latent heating on the mean flow adjustment in idealized baroclinic life cycles. The life cycles are simulated in an idealized moist general circulation

  13. An Improved Heat Budget Estimation Including Bottom Effects for General Ocean Circulation Models

    NASA Technical Reports Server (NTRS)

    Carder, Kendall; Warrior, Hari; Otis, Daniel; Chen, R. F.

    2001-01-01

    This paper studies the effects of the underwater light field on heat-budget calculations of general ocean circulation models for shallow waters. The presence of a bottom significantly alters the estimated heat budget in shallow waters, which affects the corresponding thermal stratification and hence modifies the circulation. Based on the data collected during the COBOP field experiment near the Bahamas, we have used a one-dimensional turbulence closure model to show the influence of the bottom reflection and absorption on the sea surface temperature field. The water depth has an almost one-to-one correlation with the temperature rise. Effects of varying the bottom albedo by replacing the sea grass bed with a coral sand bottom, also has an appreciable effect on the heat budget of the shallow regions. We believe that the differences in the heat budget for the shallow areas will have an influence on the local circulation processes and especially on the evaporative and long-wave heat losses for these areas. The ultimate effects on humidity and cloudiness of the region are expected to be significant as well.

  14. Definition of a generalized diabatic circulation based on a variational approach

    NASA Astrophysics Data System (ADS)

    Medvedev, A. S.

    2007-08-01

    Diabatic-circulation diagnostics with the use of the distributions of heating rates and potential temperature requires that, in each particular case, a special and ambiguously defined correction to the stream function be introduced to turn a globally averaged vertical velocity to zero at any isobaric level. Up to now, the physical nature of this correction has been little explained and it has been usually written in a form that has not been substantiated to a sufficient extent. In this paper, this correction and its uncertainty are related to the eddy term, which is usually neglected in the concept of diabatic velocities. The decomposition of wave fluxes into advective and diffusion components is not unique. As a result, one can formulate a variational problem of minimizing the diffusion component of the wave flux and, thus, the problem of finding advective velocities, which involve the maximum of eddy-induced advection. A unique solution of this problem is obtained, and the relation of the solution to the “standard” diabatic circulation is studied. It is shown that, in the approximation of quasi-horizontal isentropes, the generalized diabatic stream function is identical with the “standard“ stream function. This result partially justifies the correction that is commonly used in calculations of the diabatic circulation.

  15. Tropical Pacific moisture variability: Its detection, synoptic structure and consequences in the general circulation

    NASA Technical Reports Server (NTRS)

    Mcguirk, James P.

    1990-01-01

    Satellite data analysis tools are developed and implemented for the diagnosis of atmospheric circulation systems over the tropical Pacific Ocean. The tools include statistical multi-variate procedures, a multi-spectral radiative transfer model, and the global spectral forecast model at NMC. Data include in-situ observations; satellite observations from VAS (moisture, infrared and visible) NOAA polar orbiters (including Tiros Operational Satellite System (TOVS) multi-channel sounding data and OLR grids) and scanning multichannel microwave radiometer (SMMR); and European Centre for Medium Weather Forecasts (ECHMWF) analyses. A primary goal is a better understanding of the relation between synoptic structures of the area, particularly tropical plumes, and the general circulation, especially the Hadley circulation. A second goal is the definition of the quantitative structure and behavior of all Pacific tropical synoptic systems. Finally, strategies are examined for extracting new and additional information from existing satellite observations. Although moisture structure is emphasized, thermal patterns are also analyzed. Both horizontal and vertical structures are studied and objective quantitative results are emphasized.

  16. General circulation modeling of the thermosphere-ionosphere during a geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Yiǧit, Erdal; Immel, Thomas; Ridley, Aaron; Frey, Harald U.; Moldwin, Mark

    2016-07-01

    Using a three-dimensional general circulation model (GCM) of the upper atmosphere, we investigate the response of the thermosphere-ionosphere system to the August 2011 major geomagnetic storm. The GCM is driven by measured storm-time input data of the Interplanetary Magnetic Field (IMF), solar activity, and auroral activity. Simulations for quiet steady conditions over the same period are performed as well in order to assess the response of the neutral and plasma parameters to the storm. During the storm, the high-latitude mean ion flows are enhanced by up to ~150%. Overall, the global mean neutral temperature increases by up to 15%, while the maximum thermal response is higher in the winter Southern Hemisphere at high-latitudes than the summer Northern Hemisphere: 40% vs. 20% increase in high-latitude mean temperature, respectively. The global mean Joule heating of the neutral atmosphere increases by more than a factor of three. There are distinct hemispheric differences in the magnitude and morphology of the horizontal ion flows and thermospheric circulation during the different phases of the storm. The thermospheric circulation demonstrates the largest amount of hemispheric differences during the later stages of the storm. Dynamical diagnostics show that advective forcing contributes to hemispheric differences.

  17. Global aspects of the Los Alamos general circulation model hydrologic cycle

    NASA Technical Reports Server (NTRS)

    Roads, J. O.; Chen, S.-C.; Kao, J.; Langley, D.; Glatzmaier, G.

    1992-01-01

    The global hydrologic cycle in the Los Alamos general circulation model (GCM) is compared to available global observations. Global observations of the water vapor, water-vapor flux and water-vapor flux divergence are derived from the National Meteorological Center's final analysis for the period 1986-1989. The new precipitation data set of Legates and Willmott (1990) is used for the global precipitation observations. Global evaporation is derived as a residual of the precipitation and water-vapor flux divergence. There are a number of similarities as well as discrepancies between the GCM and observations. The large-scale nondivergent and divergent GCM circulations are remarkably similar to the observed circulations; the large-scale GCM precipitation and evaporation patterns are also qualitatively similar to observations. Discrepancies are mainly quantitative and small-scale in nature: the GCM atmosphere is relatively dry which results in a slightly greater evaporation and precipitation rate than is observed; the GCM South Pacific convergence zone is displaced too far to the northwest.

  18. Progress in General Circulation Modeling of Recent Climate Change on Mars

    NASA Astrophysics Data System (ADS)

    Haberle, R. M.

    2003-12-01

    The Mars Global Surveyor and Odyssey spacecraft reveal evidence that Mars may have experienced significant climate change in the recent past (105 - 108 My). Examples include gullies, cold-based tropical glaciers, paleolakes, youthful near-surface ice, and recent localized heavy erosion. Except for the gullies and erosion, the evidence for recent climate changes requires ice and/or liquid water at low latitudes. An obvious question, therefore, is how is it possible for ice and/or liquid water to exist at low latitudes which is not possible in the present climate system? Possible mechanisms for recent climate change are volcanism, impacts, polar wander, solar variability, and orbital changes. Of these, orbital changes are the least controversial and most widely accepted mechanism for climate change. Jakosky and Carr (1985) used simple scaling arguments to suggest that at high obliquity water evaporating from the north polar cap would be transported southward by the general circulation and precipitate out at low latitudes forming tropical ice deposits. General circulation models have since confirmed this prediction. However the location and abundance of the GCM-predicted deposits varies from model to model for a given orbital configuration. The reason for this variability is probably related to how the processes that control the water cycle are represented in the models. Thus far, the models run for these high obliquity cases have simple representations of cloud microphysical processes, and totally ignore the radiative effects of water vapor and clouds. Regolith exchange and dust/ice interactions are also neglected. This talk will review the current status of general circulation modeling of recent climate change and the directions future efforts are headed towards. Reference: Jakosky, B.M., and M.H. Carr (1985). Nature, 315, 559-561.

  19. General circulation model simulations of winter and summer sea-level pressures over North America

    USGS Publications Warehouse

    McCabe, G.J.; Legates, D.R.

    1992-01-01

    In this paper, observed sea-level pressures were used to evaluate winter and summer sea-level pressures over North America simulated by the Goddard Institute for Space Studies (GISS) and the Geophysical Fluid Dynamics Laboratory (GFDL) general circulation models. The objective of the study is to determine how similar the spatial and temporal distributions of GCM-simulated daily sea-level pressures over North America are to observed distributions. Overall, both models are better at reproducing observed within-season variance of winter and summer sea-level pressures than they are at simulating the magnitude of mean winter and summer sea-level pressures. -from Authors

  20. Mars atmospheric dynamics as simulated by the NASA AMES General Circulation Model. II - Transient baroclinic eddies

    NASA Astrophysics Data System (ADS)

    Barnes, J. R.; Pollack, J. B.; Haberle, R. M.; Leovy, C. B.; Zurek, R. W.; Lee, H.; Schaeffer, J.

    1993-02-01

    A large set of experiments performed with the NASA Ames Mars General Circulation Model is analyzed to determine the properties, structure, and dynamics of the simulated transient baroclinic eddies. There is strong transient baroclinic eddy activity in the extratropics of the Northern Hemisphere during the northern autumn, winter, and spring seasons. The eddy activity remains strong for very large dust loadings, though it shifts northward. The eastward propagating eddies are characterized by zonal wavenumbers of 1-4 and periods of about 2-10 days. The properties of the GCM baroclinic eddies in the northern extratropics are compared in detail with analogous properties inferred from Viking Lander meteorology observations.

  1. Cloud-radiative effects on implied oceanic energy transports as simulated by atmospheric general circulation models

    SciTech Connect

    Gleckler, P.J.; Randall, D.A.; Boer, G.

    1994-03-01

    This paper reports on energy fluxes across the surface of the ocean as simulated by fifteen atmospheric general circulation models in which ocean surface temperatures and sea-ice boundaries are prescribed. The oceanic meridional energy transport that would be required to balance these surface fluxes is computed, and is shown to be critically sensitive to the radiative effects of clouds, to the extent that even the sign of the Southern Hemisphere ocean energy transport can be affected by the errors in simulated cloud-radiation interactions.

  2. Computational design of the basic dynamical processes of the UCLA general circulation model

    NASA Technical Reports Server (NTRS)

    Arakawa, A.; Lamb, V. R.

    1977-01-01

    The 12-layer UCLA general circulation model encompassing troposphere and stratosphere (and superjacent 'sponge layer') is described. Prognostic variables are: surface pressure, horizontal velocity, temperature, water vapor and ozone in each layer, planetary boundary layer (PBL) depth, temperature, moisture and momentum discontinuities at PBL top, ground temperature and water storage, and mass of snow on ground. Selection of space finite-difference schemes for homogeneous incompressible flow, with/without a free surface, nonlinear two-dimensional nondivergent flow, enstrophy conserving schemes, momentum advection schemes, vertical and horizontal difference schemes, and time differencing schemes are discussed.

  3. Winter polar warmings and the meridional transport on Mars simulated with a general circulation model

    NASA Astrophysics Data System (ADS)

    Medvedev, Alexander S.; Hartogh, Paul

    2007-01-01

    Winter polar warmings in the middle atmosphere of Mars occur due to the adiabatic heating associated with the downward branch of the cross-equatorial meridional circulation. Thus, they are the manifestation of the global meridional transport rather than of local radiative effects. We report on a series of numerical experiments with a recently developed general circulation model of the martian atmosphere to examine the relative roles of the mechanical and thermal forcing in the meridional transport. The experiments were focused on answering the question of whether the martian circulation is consistent with the thermally driven nearly inviscid Hadley cell, as was pointed out by some previous studies, or it is forced mainly by zonally asymmetric eddies. It is demonstrated that, under realistic conditions in the middle atmosphere, the meridional transport is maintained primarily by dissipating large-scale planetary waves and solar tides. This mechanism is similar to the "extratropical pump" in the middle atmosphere on Earth. Only in the run with artificially weak zonal disturbances, was the circulation reminiscent of thermally induced Hadley cells. In the experiment with an imposed dust storm, the modified atmospheric refraction changes the vertical propagation of the eddies. As the result, the Eliassen-Palm fluxes convergence increases in high winter latitudes of the middle atmosphere, the meridional transport gets stronger, and the polar temperature rises. Additional numerical experiments demonstrated that insufficient model resolution, increased numerical dissipation, and, especially, neglect of non-LTE effects for the 15 μm CO 2 band could weaken the meridional transport and the magnitude of polar warmings in GCMs.

  4. 3-D Seismic Interpretation

    NASA Astrophysics Data System (ADS)

    Moore, Gregory F.

    2009-05-01

    This volume is a brief introduction aimed at those who wish to gain a basic and relatively quick understanding of the interpretation of three-dimensional (3-D) seismic reflection data. The book is well written, clearly illustrated, and easy to follow. Enough elementary mathematics are presented for a basic understanding of seismic methods, but more complex mathematical derivations are avoided. References are listed for readers interested in more advanced explanations. After a brief introduction, the book logically begins with a succinct chapter on modern 3-D seismic data acquisition and processing. Standard 3-D acquisition methods are presented, and an appendix expands on more recent acquisition techniques, such as multiple-azimuth and wide-azimuth acquisition. Although this chapter covers the basics of standard time processing quite well, there is only a single sentence about prestack depth imaging, and anisotropic processing is not mentioned at all, even though both techniques are now becoming standard.

  5. A General Method for Evaluation of 2D and 3D Domain Integrals Without Domain Discretization and its Application in BEM

    NASA Astrophysics Data System (ADS)

    Hematiyan, M. R.

    2007-03-01

    A robust method is presented to evaluate 2D and 3D domain integrals without domain discretization. Each domain integral is transformed into a double integral, a boundary integral and a 1D integral. Both integrals are evaluated by adaptive Simpson quadrature method. The method can be used to evaluate domain integrals over simply or multiply connected regions with any arbitrary form of integrands. As an application of the method, domain integrals produced in boundary element formulation of potential and elastostatic problems are analyzed. Several examples are provided to show the validity and accuracy of the method.

  6. The general circulation in the eastern Algerian subbasin inferred from the ELISA experiment

    NASA Astrophysics Data System (ADS)

    Aubertin, E.; Millot, C.; Taupier-Letage, I.; Albérola, C.; Robin, S.; Font, J.

    2003-04-01

    About 40 current meters were set at nominal depths of 100, 350, 1000, 1800 and 2700 m on 9 moorings in the eastern Algerian subbasin from July 1997 to July 1998 during the ELISA operation (http://www.com.univ-mrs.fr/ELISA/). Most moorings were located on the 2800-m isobath, and all data sets were checked using the tidal currents analysis (Albérola et al., 1995). They allow i) confirming known features about the alongslope circulation, ii) proving that Algerian Eddies (AE's) can extend down to the bottom and iii) evidencing an anticlockwise circulation at intermediate and greater depths in the whole subbasin. i) At about 50 km from the Algerian and Sardinian coastlines, the general circulation is clearly alongslope and anticlockwise at all depths, as during previous experiments (Millot, 1994; Bouzinac et al., 1999). It is also confirmed that alongslope currents are generally larger closer to the bottom than at intermediate depths, with most annual means from 350 to 2700 m in the range 3-6 cm/s, up to about 10 cm/s at 2700 m on one mooring. This permanent (unless disturbed by AE's, see ii)) and extremely large circulation is still not well simulated by the general circulation models, which still prevents from getting a correct understanding of the functioning of the whole western basin. ii) During the experiment, three 100-200 km AE's (96-1, 97-1, and 98-2) have been identified following the anticlockwise circuit that was first specified by Fuda et al. (2000) in the study area. One of them (96-1), which had a lifetime of about 3 years (Puillat et al., 2002), remained stationary during about 5 months and was well sampled at that time by 3 moorings at least. This AE, as all AE's previously sampled (Millot et al., 1997; Ruiz et al., 2002), was clearly an anticyclone, not only in the surface AW layer, but also in the whole deep layer (i.e. down to 2800 m). Alongslope, the eddy-associated current is opposed to the general circulation at all depths, and can even be larger

  7. Venus in 3D

    NASA Technical Reports Server (NTRS)

    Plaut, Jeffrey J.

    1993-01-01

    Stereographic images of the surface of Venus which enable geologists to reconstruct the details of the planet's evolution are discussed. The 120-meter resolution of these 3D images make it possible to construct digital topographic maps from which precise measurements can be made of the heights, depths, slopes, and volumes of geologic structures.

  8. 2D and 3D documentation of St. Nicolas baroque church for the general reconstruction using laser scanning and photogrammetry technologies combination

    NASA Astrophysics Data System (ADS)

    Křemen, Tomáš; Koska, Bronislav

    2013-04-01

    Total reconstruction of a historical object is a complicated process consisting of several partial steps. One of these steps is acquiring high-quality data for preparation of the project documentation. If these data are not available from the previous periods, it is necessary to proceed to a detailed measurement of the object and to create a required drawing documentation. New measurement of the object brings besides its costs also several advantages as complex content and form of drawings exactly according to the requirements together with their high accuracy. The paper describes measurement of the Baroque church by the laser scanning method extended by the terrestrial and air photogrammetry. It deals with processing the measured data and creating the final outputs, which is a 2D drawing documentation, orthophotos and a 3D model. Attention is focused on their problematic parts like interconnection of the measurement data acquired by various technologies, creation of orthophotos and creation of the detailed combined 3D model of the church exterior. Results of this work were used for preparation of the planned reconstruction of the object.

  9. 3D photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Carson, Jeffrey J. L.; Roumeliotis, Michael; Chaudhary, Govind; Stodilka, Robert Z.; Anastasio, Mark A.

    2010-06-01

    Our group has concentrated on development of a 3D photoacoustic imaging system for biomedical imaging research. The technology employs a sparse parallel detection scheme and specialized reconstruction software to obtain 3D optical images using a single laser pulse. With the technology we have been able to capture 3D movies of translating point targets and rotating line targets. The current limitation of our 3D photoacoustic imaging approach is its inability ability to reconstruct complex objects in the field of view. This is primarily due to the relatively small number of projections used to reconstruct objects. However, in many photoacoustic imaging situations, only a few objects may be present in the field of view and these objects may have very high contrast compared to background. That is, the objects have sparse properties. Therefore, our work had two objectives: (i) to utilize mathematical tools to evaluate 3D photoacoustic imaging performance, and (ii) to test image reconstruction algorithms that prefer sparseness in the reconstructed images. Our approach was to utilize singular value decomposition techniques to study the imaging operator of the system and evaluate the complexity of objects that could potentially be reconstructed. We also compared the performance of two image reconstruction algorithms (algebraic reconstruction and l1-norm techniques) at reconstructing objects of increasing sparseness. We observed that for a 15-element detection scheme, the number of measureable singular vectors representative of the imaging operator was consistent with the demonstrated ability to reconstruct point and line targets in the field of view. We also observed that the l1-norm reconstruction technique, which is known to prefer sparseness in reconstructed images, was superior to the algebraic reconstruction technique. Based on these findings, we concluded (i) that singular value decomposition of the imaging operator provides valuable insight into the capabilities of

  10. Integrated cumulus ensemble and turbulence (ICET): An integrated parameterization system for general circulation models (GCMs)

    SciTech Connect

    Evans, J.L.; Frank, W.M.; Young, G.S.

    1996-04-01

    Successful simulations of the global circulation and climate require accurate representation of the properties of shallow and deep convective clouds, stable-layer clouds, and the interactions between various cloud types, the boundary layer, and the radiative fluxes. Each of these phenomena play an important role in the global energy balance, and each must be parameterized in a global climate model. These processes are highly interactive. One major problem limiting the accuracy of parameterizations of clouds and other processes in general circulation models (GCMs) is that most of the parameterization packages are not linked with a common physical basis. Further, these schemes have not, in general, been rigorously verified against observations adequate to the task of resolving subgrid-scale effects. To address these problems, we are designing a new Integrated Cumulus Ensemble and Turbulence (ICET) parameterization scheme, installing it in a climate model (CCM2), and evaluating the performance of the new scheme using data from Atmospheric Radiation Measurement (ARM) Program Cloud and Radiation Testbed (CART) sites.

  11. a General Circulation Model Investigation of the Atmospheric Response to EL Nino

    NASA Astrophysics Data System (ADS)

    de Aragao, Jose Oribe Rocha

    The observed atmospheric response to sea surface temperature (SST) anomalies associated with El Nino episodes is simulated with the use of a general circulation model (GCM) of the atmosphere. A series of experiments has been performed with the Rasmusson and Carpenter six-episode (El Nino) composite SST anomaly (SSTA) in the tropical Pacific superimposed upon the prescribed climatological SST (CSST). Five independent 400-day runs were made beginning in April of the El Nino year (Year 0) and ending in May of the year after the maximum SSTA in the tropical Pacific (Year +1). Each of the integrations started from different initial conditions selected from different years in a 20 -year control run. The five-year El Nino integration was compared with the control run by analyzing the ensemble monthly, seasonal and annual mean statistics. The model's tropical response resembles the anomalous features found in previous studies. Some features are expected from the constraint imposed by the vorticity balance in the linear theory. For example, the upper level anticyclone pair and the lower level cyclonic circulation centers in the central Pacific are present for almost all months. These responses are significant and seem to be related to the location of both the maximum in CSST and the maximum in SSTA. An anomalous Walker Circulation is found in the vertical plane along the equatorial region. Rainfall departures from the long-term mean are associated with the anomalous Walker Circulation. An analysis of rainfall data over Northeast Brazil reveals sup- pressed rainfall in this area during the rainy season of Year(+1). Significant lower-than-normal rainfall is also found in the model's response during that period. This reduction in precipitation is associated with the downward branch of the anomalous Walker Circulation. The model's extratropical response is weaker than the tropical response and is not well organized. A Pacific/North American (PNA) pattern is present during the

  12. Comparing the Degree of Land-Atmosphere Interaction in Four Atmospheric General Circulation Models

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Dirmeyer, Paul A.; Hahmann, Andrea N.; Ijpelaar, Ruben; Tyahla, Lori; Cox, Peter; Suarez, Max J.; Houser, Paul R. (Technical Monitor)

    2001-01-01

    Land-atmosphere feedback, by which (for example) precipitation-induced moisture anomalies at the land surface affect the overlying atmosphere and thereby the subsequent generation of precipitation, has been examined and quantified with many atmospheric general circulation models (AGCMs). Generally missing from such studies, however, is an indication of the extent to which the simulated feedback strength is model dependent. Four modeling groups have recently performed a highly controlled numerical experiment that allows an objective inter-model comparison of land-atmosphere feedback strength. The experiment essentially consists of an ensemble of simulations in which each member simulation artificially maintains the same time series of surface prognostic variables. Differences in atmospheric behavior between the ensemble members then indicates the degree to which the state of the land surface controls atmospheric processes in that model. A comparison of the four sets of experimental results shows that feedback strength does indeed vary significantly between the AGCMs.

  13. GCM studies of the influence of vegetation on the general circulation: The role of albedo in modulating climate change. [GCM (general circulation model)

    SciTech Connect

    Dirmeyer, P.A.

    1992-01-01

    An atmospheric general circulation model (GCM) coupled to a simple biosphere model is used to examine the role of vegetation change on climate. Various biomes are substituted to simulate degradation of vegetation. It is found that albedo change plays a distinct role in the local decrease of rainfall. Changes in vegetation morphology and physiology do not cause catastrophic decreases in precipitation. Simulations of Amazon deforestation show that the climate response is very dependent on the amount of change in albedo between rainforest and degraded grass. Precipitation drops as albedo increases. The change in plant physiology decreases evapotranspiration, but moisture convergence increases to offset the drying. This compensation is a result of cloud feedback in this model, and does not occur when cloudiness is prescribed. Experiments with idealized boundary conditions show a similar dependence of rainfall on albedo in cases of tropical deforestation, subtropical desertification, and mid-latitude deforestation. In the topics, rainfall decreases over land only when reflectivity is increased, even when the rainforest is left intact. The monsoon precipitation of the subtropical experiment fails when savannah is replaced by high-albedo desert. When low-albedo desert is used, the decrease in summer rainfall is small. When mid-latitude forest is replaced by grassland, precipitation patterns shift, but net rainfall remains unchanged. Additional simulations of mid-latitude drought show that low soil moisture leads to moderate spring and summer droughts, but dry soil combined with dormant vegetation produces extremely severe droughts. Soil moisture deficits were more persistent when vegetation did not go dormant.

  14. Thermodynamics of the general diffusion process: Equilibrium supercurrent and nonequilibrium driven circulation with dissipation

    NASA Astrophysics Data System (ADS)

    Qian, H.

    2015-07-01

    Unbalanced probability circulation, which yields cyclic motions in phase space, is the defining characteristics of a stationary diffusion process without detailed balance. In over-damped soft matter systems, such behavior is a hallmark of the presence of a sustained external driving force accompanied with dissipations. In an under-damped and strongly correlated system, however, cyclic motions are often the consequences of a conservative dynamics. In the present paper, we give a novel interpretation of a class of diffusion processes with stationary circulation in terms of a Maxwell-Boltzmann equilibrium in which cyclic motions are on the level set of stationary probability density function thus non-dissipative, e.g., a supercurrent. This implies an orthogonality between stationary circulation J ss ( x) and the gradient of stationary probability density f ss ( x) > 0. A sufficient and necessary condition for the orthogonality is a decomposition of the drift b( x) = j( x) + D( x)∇φ( x) where ∇ṡ j( x) = 0 and j( x) ṡ∇φ( x) = 0. Stationary processes with such Maxwell-Boltzmann equilibrium has an underlying conservative dynamics , and a first integral ϕ( x) ≡ -ln f ss (x) = const, akin to a Hamiltonian system. At all time, an instantaneous free energy balance equation exists for a given diffusion system; and an extended energy conservation law among an entire family of diffusion processes with different parameter α can be established via a Helmholtz theorem. For the general diffusion process without the orthogonality, a nonequilibrium cycle emerges, which consists of external driven φ-ascending steps and spontaneous φ-descending movements, alternated with iso-φ motions. The theory presented here provides a rich mathematical narrative for complex mesoscopic dynamics, with contradistinction to an earlier one [H. Qian et al., J. Stat. Phys. 107, 1129 (2002)]. This article is supplemented with comments by H. Ouerdane and a final reply by the author.

  15. An eddy-permitting oceanic general circulation model and its preliminary evaluation

    NASA Astrophysics Data System (ADS)

    Liu, Hailong; Zhang, Xuehong; Li, Wei; Yu, Yongqiang; Yu, Rucong

    2004-10-01

    An eddy-permitting, quasi-global oceanic general circulation model, LICOM (LASG/IAP (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics) Climate System Ocean Model), with a uniform grid of 0.5° × 0.5° is established. Forced by wind stresses from Hellerman and Rosenstain (1983), a 40-yr integration is conducted with sea surface temperature and salinity being restored to the Levitus 94 datasets. The evaluation of the annual mean climatology of the LICOM control run shows that the large-scale circulation can be well reproduced. A comparison between the LICOM control run and a parallel integration of L30T63, which has the same framework but a coarse resolution, is also made to confirm the impact of resolution on the model performance. On account of the reduction of horizontal viscosity with the enhancement of the horizontal resolution, LICOM improves the simulation with respect to not only the intensity of the large scale circulations, but also the magnitude and structure of the Equatorial Undercurrent and South Equatorial Current. Taking advantage of the fine grid size, the pathway of the Indonesian Throughflow (ITF) is better represented in LICOM than in L30T63. The transport of ITF in LICOM is more convergent in the upper layer. As a consequence, the Indian Ocean tends to get warmer in LICOM. The poleward heat transports for both the global and individual basins are also significantly improved in LICOM. A decomposed analysis indicates that the transport due to the barotropic gyre, which primarily stands for the barotropic effect of the western boundary currents, plays a crucial role in making the difference.

  16. TACO3D. 3-D Finite Element Heat Transfer Code

    SciTech Connect

    Mason, W.E.

    1992-03-04

    TACO3D is a three-dimensional, finite-element program for heat transfer analysis. An extension of the two-dimensional TACO program, it can perform linear and nonlinear analyses and can be used to solve either transient or steady-state problems. The program accepts time-dependent or temperature-dependent material properties, and materials may be isotropic or orthotropic. A variety of time-dependent and temperature-dependent boundary conditions and loadings are available including temperature, flux, convection, and radiation boundary conditions and internal heat generation. Additional specialized features treat enclosure radiation, bulk nodes, and master/slave internal surface conditions (e.g., contact resistance). Data input via a free-field format is provided. A user subprogram feature allows for any type of functional representation of any independent variable. A profile (bandwidth) minimization option is available. The code is limited to implicit time integration for transient solutions. TACO3D has no general mesh generation capability. Rows of evenly-spaced nodes and rows of sequential elements may be generated, but the program relies on separate mesh generators for complex zoning. TACO3D does not have the ability to calculate view factors internally. Graphical representation of data in the form of time history and spatial plots is provided through links to the POSTACO and GRAPE postprocessor codes.

  17. Venus atmosphere simulated by a high-resolution general circulation model

    NASA Astrophysics Data System (ADS)

    Sugimoto, Norihiko

    2016-07-01

    An atmospheric general circulation model (AGCM) for Venus on the basis of AFES (AGCM For the Earth Simulator) have been developed (e.g., Sugimoto et al., 2014a) and a very high-resolution simulation is performed. The highest resolution of the model is T319L120; 960 times 480 horizontal grids (grid intervals are about 40 km) with 120 vertical layers (layer intervals are about 1 km). In the model, the atmosphere is dry and forced by the solar heating with the diurnal and semi-diurnal components. The infrared radiative process is simplified by adopting Newtonian cooling approximation. The temperature is relaxed to a prescribed horizontally uniform temperature distribution, in which a layer with almost neutral static stability observed in the Venus atmosphere presents. A fast zonal wind in a solid-body rotation is given as the initial state. Starting from this idealized superrotation, the model atmosphere reaches a quasi-equilibrium state within 1 Earth year and this state is stably maintained for more than 10 Earth years. The zonal-mean zonal flow with weak midlatitude jets has almost constant velocity of 120 m/s in latitudes between 45°S and 45°N at the cloud top levels, which agrees very well with observations. In the cloud layer, baroclinic waves develop continuously at midlatitudes and generate Rossby-type waves at the cloud top (Sugimoto et al., 2014b). At the polar region, warm polar vortex zonally surrounded by a cold latitude band (cold collar) is well reproduced (Ando et al., 2016). As for horizontal kinetic energy spectra, divergent component is broadly (k>10) larger than rotational component compared with that on Earth (Kashimura et al., in preparation). Finally, recent results for thermal tides and small-scale waves will be shown in the presentation. Sugimoto, N. et al. (2014a), Baroclinic modes in the Venus atmosphere simulated by GCM, Journal of Geophysical Research: Planets, Vol. 119, p1950-1968. Sugimoto, N. et al. (2014b), Waves in a Venus general

  18. Snowline instability in a general circulation model: application to Carboniferous glaciation

    SciTech Connect

    Crowley, T.J.; Yip, Kuor-Kier, J.; Baum, S.K.

    1994-11-01

    For over twenty years it has been known that energy balance models (EBMs) with snow-albedo feedback are characterized by unstable behavior in some areas of parameter space. This behaviour leads to rapid changes in snow area due to small changes in forcing, and has been termed the small ice cap instability (SICI). It has never been clarified whether this behaviour reflects a real feature of the climate system or a limitation in EBMs. In this study we demonstrate that evidence for similar unstable behavior can also be found in an atmospheric general circulation model (GCM), using a realistic set of boundary conditions for the Carboniferous (300 Ma), one of the most extensive periods of glaciation in Earth history. When solar luminosity is sequentially lowered to near values appropriate for the Carboniferous, there is a discontinuous increase in summer snow area. The instability occurs in approximately the same area of parameter space as one previously found in an EBM. Analysis of selected fields indicates that the circulation is primarily affected in the area of snow increase; far-field effects are minimal. There is good agreement between model-generated summer snowcover and one reconstruction of Carboniferous ice cover. Although more work is required on this topic, our results provide increased support for the possibility that the snowline instability represents a real feature of the climate system, and that it may help explain some cases of glacial inception and abrupt transitions in Earth history. 63 refs., 20 figs.

  19. Improved short-term variability in the thermosphere-ionosphere-mesosphere-electrodynamics general circulation model

    NASA Astrophysics Data System (ADS)

    Häusler, K.; Hagan, M. E.; Baumgaertner, A. J. G.; Maute, A.; Lu, G.; Doornbos, E.; Bruinsma, S.; Forbes, J. M.; Gasperini, F.

    2014-08-01

    We report on a new source of tidal variability in the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM). Lower boundary forcing of the TIME-GCM for a simulation of November-December 2009 based on 3-hourly Modern-Era Retrospective Analysis for Research and Application (MERRA) reanalysis data includes day-to-day variations in both diurnal and semidiurnal tides of tropospheric origin. Comparison with TIME-GCM results from a heretofore standard simulation that includes climatological tropospheric tides from the global-scale wave model reveal evidence of the impacts of MERRA forcing throughout the model domain, including measurable tidal variability in the TIME-GCM upper thermosphere. Additional comparisons with measurements made by the Gravity field and steady-state Ocean Circulation Explorer satellite show improved TIME-GCM capability to capture day-to-day variations in thermospheric density for the November-December 2009 period with the new MERRA lower boundary forcing.

  20. Geochemical constraints on ocean general circulation models. Final report, May 1, 1995--April 30, 1997

    SciTech Connect

    Broecker, W.S.

    1998-05-17

    A better understanding of the manner in which the ocean operates is essential to the preparation for the consequences of the generation of CO{sub 2} by fossil fuel burning. Examples are as follows: (1) the ocean will ultimately take up a major fraction of the CO{sub 2} produced, but this uptake is retarded by the slow mixing rates, in order to predict the uptake, researchers must develop and validate general circulation models for the ocean; (2) during glacial time large global climate changes occurred. The changes were abrupt happening in a few decades. The trigger for these changes appears to have been reorganizations of the large-scale thermohaline circulation of the ocean. Models suggest that if the CO{sub 2} content of the atmosphere rises to more than 700 ppm, then a possibility exists that another such reorganization might occur. Hence, researchers must learn more about the factors influencing deep-water formation both in the northern Atlantic and in the Souther Ocean. The thrust of this research was to develop constraints based on the distributions of chemicals and tracers in the sea. The accomplishments are outlined in this report.

  1. [The Contribution of Vascular Capacity and Blood Volume to Maintain Stable Blood Circulation during General Anesthesia].

    PubMed

    Shigemi, Kenji

    2016-05-01

    To maintain proper cardiac preload is one of the most effective procedures for the systemic circulation remaining stable. In particular, the balance between vascular capacity and total blood volume must be maintained within appropriate range by the administration of fluids, blood and/or vasoactive drugs with mean circulatory filling pressure (Pmcf), central venous pressure (CVP) or stroke volume variation (SVV). End-diastolic left ventricular volume (Ved) is theoretically the best index of cardiac preload; however, without transesophageal echocardbalanceiogram we cannot directly monitor Ved during anesthesia. The infused fluid volume remaining in intravascular space, the vascular capacity controlled by autonomic nervous system and/or vasoactive agents, and the unstressed blood volume properly mobilized to excess blood volume are the crucial factors to maintain cardiac output The knowledge of vascular physiology contribute the decision making to manipulate such factors to control blood circulation during general anesthesia. For example, CVP is usually maintained in the narrow range and seems to be stable; however, it must be changed just after the circulatory disturbances, such as acute bleeding, blood transfusion, and fluid infusion, and followed by gradual returning to initial value, because of the solid mechanism to preserve cardiac output

  2. Constraining a Martian general circulation model with the MAVEN/IUVS observations in the thermosphere

    NASA Astrophysics Data System (ADS)

    Moeckel, Chris; Medvedev, Alexander; Nakagawa, Hiromu; Evans, Scott; Kuroda, Takeshi; Hartogh, Paul; Yiğit, Erdal; Jain, Sonal; Lo, Daniel; Schneider, Nicholas M.; Jakosky, Bruce

    2016-10-01

    The recent measurements of the number density of atomic oxygen by Mars Atmosphere and Volatile EvolutioN/ Imaging UltraViolet Spectrograph (MAVEN/IUVS) have been implemented for the first time into a global circulation model to quantify the effect on the Martian thermosphere. The number density has been converted to 1D volume mixing ratio and this profile is compared to the atomic oxygen scenarios based on chemical models. Simulations were performed with the Max Planck Institute Martian General Circulation Model (MPI-MGCM). The simulations closely emulate the conditions at the time of observations. The results are compared to the IUVS-measured CO2 number density and temperature above 130 km to gain knowledge of the processes in the upper atmosphere and further constrain them in MGCMs. The presentation will discuss the role and importance in the thermosphere of the following aspects: (a) impact of the observed atomic oxygen, (b) 27-day solar cycle variations, (c) varying dust load in the lower atmosphere, and (d) gravity waves.

  3. Low-level jets in the NASA Ames Mars general circulation model

    NASA Astrophysics Data System (ADS)

    Joshi, M. M.; Haberle, R. M.; Barnes, J. R.; Murphy, J. R.; Schaeffer, J.

    1997-03-01

    Previous simulations of the Martian atmosphere have shown how topography acts to confine the low-level Hadley cell flow into intense jets on the eastern flanks of Tharsis and Syrtis Major. We now conduct detailed studies of these jets using the NASA Ames Mars general circulation model (MGCM). The structure of the flow is found to be sensitive to local topography as well as large-scale diabatic heating patterns, consistent with terrestrial studies, and MGCM studies carried out with simplified topography. The summer subtropical zonal winds associated with the Hadley circulation also form spatially confined intense jet cores. Diurnal variations in heating affect jet structure in three distinct ways. Global tides interact with the jets, resulting in effects such as the two reinforcing each other at the summer subtropics near midday, leading to high winds and surface stresses at this time. Slope winds act to change the character of the jets during the course of a day, especially at Syrtis Major and the Hellas basin, where slopes are large. Vertical mixing acts to decrease low-level winds during the late afternoon. The sensitivity of the results to atmospheric dust loading is examined. We finally show how a decrease in boundary layer height due to dust loading actually augments mid-afternoon jet strength near the surface. The resulting increase in maximum surface stress indicates that this is a positive feedback to dust lifting.

  4. 3D change detection - Approaches and applications

    NASA Astrophysics Data System (ADS)

    Qin, Rongjun; Tian, Jiaojiao; Reinartz, Peter

    2016-12-01

    Due to the unprecedented technology development of sensors, platforms and algorithms for 3D data acquisition and generation, 3D spaceborne, airborne and close-range data, in the form of image based, Light Detection and Ranging (LiDAR) based point clouds, Digital Elevation Models (DEM) and 3D city models, become more accessible than ever before. Change detection (CD) or time-series data analysis in 3D has gained great attention due to its capability of providing volumetric dynamics to facilitate more applications and provide more accurate results. The state-of-the-art CD reviews aim to provide a comprehensive synthesis and to simplify the taxonomy of the traditional remote sensing CD techniques, which mainly sit within the boundary of 2D image/spectrum analysis, largely ignoring the particularities of 3D aspects of the data. The inclusion of 3D data for change detection (termed 3D CD), not only provides a source with different modality for analysis, but also transcends the border of traditional top-view 2D pixel/object-based analysis to highly detailed, oblique view or voxel-based geometric analysis. This paper reviews the recent developments and applications of 3D CD using remote sensing and close-range data, in support of both academia and industry researchers who seek for solutions in detecting and analyzing 3D dynamics of various objects of interest. We first describe the general considerations of 3D CD problems in different processing stages and identify CD types based on the information used, being the geometric comparison and geometric-spectral analysis. We then summarize relevant works and practices in urban, environment, ecology and civil applications, etc. Given the broad spectrum of applications and different types of 3D data, we discuss important issues in 3D CD methods. Finally, we present concluding remarks in algorithmic aspects of 3D CD.

  5. Influence of viscosity on the reflection and transmission of an acoustic wave by a periodic array of screens. The general 3-D problem

    PubMed Central

    Homentcovschi, Dorel; Miles, Ronald N.

    2008-01-01

    An analysis is presented of the diffraction of a pressure wave by a periodic grating including the influence of the air viscosity. The direction of the incoming pressure wave is arbitrary. As opposed to the classical nonviscous case, the problem cannot be reduced to a plane problem having a definite 3-D character. The system of partial differential equations used for solving the problem consists of the compressible Navier-Stokes equations associated with no-slip boundary conditions on solid surfaces. The problem is reduced to a system of two hypersingular integral equations for determining the velocity components in the slits’ plane and a hypersingular integral equation for the normal component of velocity. These equations are solved by using Galerkin’s method with some special trial functions. The results can be applied in designing protective screens for miniature microphones realized in MEMS technology. In this case, the physical dimensions of the device are on the order of the viscous boundary layer so that the viscosity cannot be neglected. The analysis indicates that the openings in the screen should be on the order of 10 microns in order to avoid excessive attenuation of the signal. This paper also provides the variation of the transmission coefficient with frequency in the acoustical domain. PMID:19122753

  6. Explicit entrainment parameterization in the general circulation model ECHAM5-HAM

    NASA Astrophysics Data System (ADS)

    Siegenthaler-Le Drian, Colombe; Spichtinger, Peter; Lohmann, Ulrike

    2010-05-01

    The complex interactions affecting cloud lifetime and liquid water path (LWP) are not well captured in state-of-the-art general circulation models (GCM). A recent climate model intercomparison showed an overestimation of the positive correlation of LWP with aerosol optical depth by a factor of two as compared to MODIS data for almost all participating models (Quaas et al., 2009). As the authors suggest, a proper interaction of the boundary layer dynamics, particularly the inclusion of cloud top entrainment may lead to an improvement. ECHAM5 was one of the participating model. In this model, the turbulent fluxes in the planetary boundary layer are simulated using a turbulent kinetic energy - mixing length scheme. It has been showed that its performance diminishes when the resolution decreases, the different fluxes being not represented satisfactory with 31 vertical levels, particularly at the cloud top (Lenderink et al., 2000). We thus replace the turbulent fluxes by the explicit entrainment closure by Turton and Nicholls (1987) at the top of the stratocumulus capped boundary layers. The turbulent fluxes are weighted with the cloud cover to apply the entrainment closure only above clouds. In addition, we use an explicit term for the radiative cooling contribution in the buoyancy production term. We use the new version of the Hamburg general circulation model ECHAM5-HAM (Roeckner et al., 2003; Stier et al., 2005). The cloud scheme that is used for this study includes the double-moment cloud microphysics scheme for cloud droplets and ice crystals (Lohmann et al., 2007). The principal effect of the explicit entrainment is to dry and warm the planetary boundary layer. The averaged profiles are more stable and the inversion is reduced. The stratocumulus deck is reduced in all typical stratocumulus regions. In a single column version of the model, the diurnal cycle simulated in cloud cover or equivalentely in cloud water is much more representative of observed subtropical

  7. Intercomparison and interpretation of surface energy fluxes in atmospheric general circulation models

    NASA Technical Reports Server (NTRS)

    Randall, D. A.; Cess, R. D.; Blanchet, J. P.; Boer, G. J.; Dazlich, D. A.; Del Genio, A. D.; Deque, M.; Dymnikov, V.; Galin, V.; Ghan, S. J.

    1992-01-01

    Responses of the surface energy budgets and hydrologic cycles of 19 atmospheric general circulation models to an imposed, globally uniform sea surface temperature perturbation of 4 K were analyzed. The responses of the simulated surface energy budgets are extremely diverse and are closely linked to the responses of the simulated hydrologic cycles. The response of the net surface energy flux is not controlled by cloud effects; instead, it is determined primarily by the response of the latent heat flux. The prescribed warming of the oceans leads to major increases in the atmospheric water vapor content and the rates of evaporation and precipitation. The increased water vapor amount drastically increases the downwelling IR radiation at the earth's surface, but the amount of the change varies dramatically from one model to another.

  8. Stable water isotope behavior during the last glacial maximum: A general circulation model analysis

    NASA Technical Reports Server (NTRS)

    Jouzel, Jean; Koster, Randal D.; Suozzo, Robert J.; Russell, Gary L.

    1994-01-01

    Global water isotope geochemisty during the last glacial maximum (LGM) is simulated with an 8 deg x 10 deg atmospheric general circulation model (GCM). The simulation results suggest that the spatial delta O-18/temperature relationships observed for the present day and LGM climates are very similar. Furthermore, the temporal delta O-18/temperature relationship is similar to the present-day spatial relationship in regions for which the LGM/present-day temperature change is significant. This helps justify the standard practice of applying the latter to the interpretation of paleodata, despite the possible influence of other factors, such as changes in the evaportive sources of precipitation or in the seasonality of precipitation. The model suggests, for example, that temperature shifts inferred from ice core data may differ from the true shifts by only about 30%.

  9. Simulation of the great plains low-level jet and associated clouds by general circulation models

    SciTech Connect

    Ghan, S.J.; Bian, X.; Corsetti, L.

    1996-07-01

    The low-level jet frequently observed in the Great Plains of the United States forms preferentially at night and apparently influences the timing of the thunderstorms in the region. The authors have found that both the European Centre for Medium-Range Weather Forecasts general circulation model and the National Center for Atmospheric Research Community Climate Model simulate the low-level jet rather well, although the spatial distribution of the jet frequency simulated by the two GCM`s differ considerably. Sensitivity experiments have demonstrated that the simulated low-level jet is surprisingly robust, with similar simulations at much coarser horizontal and vertical resolutions. However, both GCM`s fail to simulate the observed relationship between clouds and the low-level jet. The pronounced nocturnal maximum in thunderstorm frequency associated with the low-level jet is not simulated well by either GCM, with only weak evidence of a nocturnal maximum in the Great Plains. 36 refs., 20 figs.

  10. Infrared cooling rate calculations in operational general circulation models - Comparisons with benchmark computations

    NASA Technical Reports Server (NTRS)

    Kiehl, J. T.; Lacis, A. A.; Schwarzkopf, M. D.; Fels, S. B.

    1991-01-01

    The performance of several parameterized models is described with respect to numerical prediction and climate research at GFDL, NCAR, and GISS. The radiation codes of the models were compared to benchmark calculations and other codes for the intercomparison of radiation codes in climate models (ICRCCM). Cooling rates and fluxes calculated from the models are examined in terms of their application to established general circulation models (GCMs) from the three research institutions. The newest radiation parameterization techniques show the most significant agreement with the benchmark line-by-line (LBL) results. The LBL cooling rates correspond to cooling rate profiles from the models, but the parameterization of the water vapor continuum demonstrates uncertain results. These uncertainties affect the understanding of some lower tropospheric cooling, and therefore more accurate parameterization of the water vapor continuum, as well as the weaker absorption bands of CO2 and O3 is recommended.

  11. Tropical Pacific Ocean response to observed winds in a layered general circulation model

    NASA Technical Reports Server (NTRS)

    Miller, Arthur J.; Oberhuber, Joseph M.; Graham, Nicholas E.; Barnett, Tim P.

    1992-01-01

    The effect of forcing by monthly wind-stress variability is assessed with respect to the behavior of an isopycnic coordinate general circulation model. The isopycnic model incorporates an embedded mixed layer, and the equations are given for the interior layers, the surface mixed layer, and the atmospheric forcing. The anomalous variability of several variables is examined in a simulation using data from 1970-1985 with specific attention given to the anomalous response related to the 1982-1983 ENSO. The model fields describing sea-surface temperature (SST), sea level, and currents are found to be comparable to those reported from observational campaigns. Anomalous values of SST compare best with observed data when averaged over large spatial regions, and the amplitudes of the mean horizontal currents and anomalous zonal currents are comparable except with respect to amplitude data. The present study permits the simulation of basin-scale tropical Pacific mixed-layer depth and the mean vertical velocity field.

  12. Two-Layer Variable Infiltration Capacity Land Surface Representation for General Circulation Models

    NASA Technical Reports Server (NTRS)

    Xu, L.

    1994-01-01

    A simple two-layer variable infiltration capacity (VIC-2L) land surface model suitable for incorporation in general circulation models (GCMs) is described. The model consists of a two-layer characterization of the soil within a GCM grid cell, and uses an aerodynamic representation of latent and sensible heat fluxes at the land surface. The effects of GCM spatial subgrid variability of soil moisture and a hydrologically realistic runoff mechanism are represented in the soil layers. The model was tested using long-term hydrologic and climatalogical data for Kings Creek, Kansas to estimate and validate the hydrological parameters. Surface flux data from three First International Satellite Land Surface Climatology Project Field Experiments (FIFE) intensive field compaigns in the summer and fall of 1987 in central Kansas, and from the Anglo-Brazilian Amazonian Climate Observation Study (ABRACOS) in Brazil were used to validate the mode-simulated surface energy fluxes and surface temperature.

  13. Tracer water transport and subgrid precipitation variation within atmospheric general circulation models

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Eagleson, Peter S.; Broecker, Wallace S.

    1988-01-01

    A capability is developed for monitoring tracer water movement in the three-dimensional Goddard Institute for Space Science Atmospheric General Circulation Model (GCM). A typical experiment with the tracer water model follows water evaporating from selected grid squares and determines where this water first returns to the Earth's surface as precipitation or condensate, thereby providing information on the lateral scales of hydrological transport in the GCM. Through a comparison of model results with observations in nature, inferences can be drawn concerning real world water transport. Tests of the tracer water model include a comparison of simulated and observed vertically-integrated vapor flux fields and simulations of atomic tritium transport from the stratosphere to the oceans. The inter-annual variability of the tracer water model results is also examined.

  14. The parameterization of the planetary boundary layer in the UCLA general circulation model - Formulation and results

    NASA Technical Reports Server (NTRS)

    Suarez, M. J.; Arakawa, A.; Randall, D. A.

    1983-01-01

    A planetary boundary layer (PBL) parameterization for general circulation models (GCMs) is presented. It uses a mixed-layer approach in which the PBL is assumed to be capped by discontinuities in the mean vertical profiles. Both clear and cloud-topped boundary layers are parameterized. Particular emphasis is placed on the formulation of the coupling between the PBL and both the free atmosphere and cumulus convection. For this purpose a modified sigma-coordinate is introduced in which the PBL top and the lower boundary are both coordinate surfaces. The use of a bulk PBL formulation with this coordinate is extensively discussed. Results are presented from a July simulation produced by the UCLA GCM. PBL-related variables are shown, to illustrate the various regimes the parameterization is capable of simulating.

  15. Greenhouse gas-induced climate change simulated with the CCS second-generation general circulation model

    SciTech Connect

    Boer, G.J.; Mcfarlane, N.A.; Lazare, M. )

    1992-10-01

    The Canadian Climate Centre second-generation atmospheric general circulation model coupled to a mixed-layer ocean incorporating thermodynamic sea ice is used to simulate the equilibrium climate response to a doubling of CO[sub 2]. The results of the simulation indicate a global annual warming of 3.5 C with enhanced warming found over land and at higher latitudes. Precipitation and evaporation rates increase by about 4 percent, and cloud cover decreases by 2.2 percent. Soil moisture decreases over continental Northern Hemisphere land areas in summer. The frozen component of soil moisture decreases and the liquid component increases in association with the increase of temperature at higher latitudes. The simulated accumulation rate of permanent snow cover decreases markedly over Greenland and increases slightly over Antarctica. Seasonal snow and sea ice boundaries retreat, but local decreases in planetary albedo are counteracted by tropical increases, so there is little change in the global average. 39 refs.

  16. The Venus nitric oxide night airglow - Model calculations based on the Venus Thermospheric General Circulation Model

    NASA Technical Reports Server (NTRS)

    Bougher, S. W.; Gerard, J. C.; Stewart, A. I. F.; Fesen, C. G.

    1990-01-01

    The mechanism responsible for the Venus nitric oxide (0,1) delta band nightglow observed in the Pioneer Venus Orbiter UV spectrometer (OUVS) images was investigated using the Venus Thermospheric General Circulation Model (Dickinson et al., 1984), modified to include simple odd nitrogen chemistry. Results obtained for the solar maximum conditions indicate that the recently revised dark-disk average NO intensity at 198.0 nm, based on statistically averaged OUVS measurements, can be reproduced with minor modifications in chemical rate coefficients. The results imply a nightside hemispheric downward N flux of (2.5-3) x 10 to the 9th/sq cm sec, corresponding to the dayside net production of N atoms needed for transport.

  17. The sensitivity of the general circulation to Arctic Sea ice boundaries - A numerical experiment

    NASA Technical Reports Server (NTRS)

    Herman, G. F.; Johnson, W. T.

    1978-01-01

    Results are presented for a set of numerical experiments conducted with the Goddard (formerly GISS) general circulation model. The experiments were designed to test the model atmospheric response to a single fixed and specified parameter, the total ice cover in the Davis Strait, Barents Sea, East Greenland Sea, Sea of Okhotsk and Bering Sea. Margin variations are considered that are substantially smaller than those involved in ice age or ice-free Arctic simulations. Anomaly is defined as the mean of two runs corresponding to climatological maximum sea ice conditions. Model results indicate that the ice margin anomalies are capable of altering local climates in certain regions of high and middle latitudes. Possible interactions between high latitudes and subtropical regions are suggested.

  18. Dynamical predictability in a simple general circulation model - Average error growth

    NASA Technical Reports Server (NTRS)

    Schubert, Siegfried D.; Suarez, Max

    1989-01-01

    Average predictability and error growth in a simple realistic two-level general circulation model (GCM) were investigated using a series of Monte Carlo experiments for fixed external forcing (perpetual winter in the Northern Hemisphere). It was found that, for realistic initial errors, the dependence of the limit of dynamic predictability on total wavenumber was similar to that found for the ECMWF model for the 1980/1981 winter conditions, with the lowest wavenumbers showing significant skill for forecast ranges of more than 1 month. On the other hand, for very small amplitude errors distributed according to the climate spectrum, the total error growth was superexponential, reaching a maximum growth rate (2-day doubling time) in about 1 week. A simple empirical model of error variance, which involved two broad wavenumber bands and incorporating a 3/2 power saturation term, was found to provide an excellent fit to the GCM error growth behavior.

  19. Dust Emissions, Transport, and Deposition Simulated with the NASA Finite-Volume General Circulation Model

    NASA Technical Reports Server (NTRS)

    Colarco, Peter; daSilva, Arlindo; Ginoux, Paul; Chin, Mian; Lin, S.-J.

    2003-01-01

    Mineral dust aerosols have radiative impacts on Earth's atmosphere, have been implicated in local and regional air quality issues, and have been identified as vectors for transporting disease pathogens and bringing mineral nutrients to terrestrial and oceanic ecosystems. We present for the first time dust simulations using online transport and meteorological analysis in the NASA Finite-Volume General Circulation Model (FVGCM). Our dust formulation follows the formulation in the offline Georgia Institute of Technology-Goddard Global Ozone Chemistry Aerosol Radiation and Transport Model (GOCART) using a topographical source for dust emissions. We compare results of the FVGCM simulations with GOCART, as well as with in situ and remotely sensed observations. Additionally, we estimate budgets of dust emission and transport into various regions.

  20. Surface Lander Missions to Mars: Support via Analysis of the NASA Ames Mars General Circulation Model

    NASA Technical Reports Server (NTRS)

    Murphy, James R.; Bridger, Alison F.C.; Haberle, Robert M.

    1997-01-01

    We have characterized the near-surface martian wind environment as calculated with a set of numerical simulations carried out with the NASA Ames Mars General Circulation Model (Mars GCM). These wind environments are intended to offer future spacecraft missions to the martian surface a data base from which to choose those locations which meet the mission's criteria for minimal near surface winds to enable a successful landing. We also became involved in the development and testing of the wind sensor which is currently onboard the Mars-bound Pathfinder lander. We began this effort with a comparison of Mars GCM produced winds with those measured by the Viking landers during their descent through the martian atmosphere and their surface wind measurements during the 3+ martian year lifetime of the mission. Unexpected technical difficulties in implementing the sophisticated Planetary Boundary Layer (PBL) scheme of Haberle et al. (1993) within the Mars GCM precluded our carrying out this investigation with the desired improvement to the model's treatment of the PBL. Thus, our results from this effort are not as conclusive as we had anticipated. As it turns out, similar difficulties have been experienced by other Mars modelling groups in attempting to implement very similar PBL routines into their GCMs (Mars General Circulation Model Intercomparison Workshop, held at Oxford University, United Kingdom, July 22-24, 1996; organized by J. Murphy, J. Hollingsworth, M. Joshi). These problems, which arise due to the nature of the time stepping in each of the models, are near to being resolved at the present. The model discussions which follow herein are based upon results using the existing, less sophisticated PBL routine. We fully anticipate implementing the tools we have developed in the present effort to investigate GCM results with the new PBL scheme implemented, and thereafter producing the technical document detailing results from the analysis tools developed during this

  1. High-Southern Latitudes Sulfur Cycle in an Atmospheric General Circulation Model

    NASA Astrophysics Data System (ADS)

    Cosme, E.; Genthon, C.; Martinerie, P.; Boucher, O.; Pham, M.

    2002-05-01

    This modeling study (Cosme et al., Sulfur cycle in the high southern latitudes in the LMD-ZT General Circulation Model, submitted to JGR) was motivated by the recent publication of annual time-scale records of dimethylsulfide (DMS) and dimethylsulfoxide (DMSO) in Antarctica, completing the available series of sulfate and methanesulfonic acid (MSA). Sulfur chemistry has been incorporated in the Laboratoire de Météorologie Dynamique Atmospheric General Circulation Model (AGCM), LMD-ZT, with high resolution and improved physics in the high-southern latitudes. The model predicts the concentration of 6 major sulfur species through emissions, transport, wet and dry deposition and chemistry in both gaseous and aqueous phases. Model results are broadly realistic when compared with measurements in air and snow or ice, and to results of other modeling studies, at high- and mid- southern latitudes. Although not corrected in this work, defects are identified and discussed: Atmospheric MSA concentrations are underestimated and DMSO concentrations are overestimated in summer, reflecting the lack of a DMSO sink leading to MSA; the deposition scheme used in the model may not be adapted to polar regions; DMS concentrations are underestimated in winter, and the model does not adequately reproduces interannual variability. Oceanic DMS sources appear deciding for the description of the sulfur cycle in these regions. The model suggests that ground atmospheric DMS concentrations are higher in winter than in summer, in a large part of central Antarctica. In the high-southern latitudes, high loads of DMS and DMSO are found and the main chemical sink of sulfur dioxide (SO2) is aqueous oxidation by ozone (O3), whereas oxidation by hydrogen peroxide (H2O2) dominates at the global scale.

  2. Wind driven general circulation of the Mediterranean Sea simulated with a Spectral Element Ocean Model

    NASA Astrophysics Data System (ADS)

    Molcard, A.; Pinardi, N.; Iskandarani, M.; Haidvogel, D. B.

    2002-05-01

    This work is an attempt to simulate the Mediterranean Sea general circulation with a Spectral Finite Element Model. This numerical technique associates the geometrical flexibility of the finite elements for the proper coastline definition with the precision offered by spectral methods. The model is reduced gravity and we study the wind-driven ocean response in order to explain the large scale sub-basin gyres and their variability. The study period goes from January 1987 to December 1993 and two forcing data sets are used. The effect of wind variability in space and time is analyzed and the relationship between wind stress curl and ocean response is stressed. Some of the main permanent structures of the general circulation (Gulf of Lions cyclonic gyre, Rhodes gyre, Gulf of Syrte anticylone) are shown to be induced by permanent wind stress curl structures. The magnitude and spatial variability of the wind is important in determining the appearance or disappearance of some gyres (Tyrrhenian anticyclonic gyre, Balearic anticyclonic gyre, Ionian cyclonic gyre). An EOF analysis of the seasonal variability indicates that the weakening and strengthening of the Levantine basin boundary currents is a major component of the seasonal cycle in the basin. The important discovery is that seasonal and interannual variability peak at the same spatial scales in the ocean response and that the interannual variability includes the change in amplitude and phase of the seasonal cycle in the sub-basin scale gyres and boundary currents. The Coriolis term in the vorticity balance seems to be responsible for the weakening of anticyclonic structures and their total disappearance when they are close to a boundary. The process of adjustment to winds produces a train of coastally trapped gravity waves which travel around the eastern and western basins, respectively in approximately 6 months. This corresponds to a phase velocity for the wave of about 1 m/s, comparable to an average velocity of

  3. Circulating Irisin Concentrations Are Associated with a Favourable Lipid Profile in the General Population

    PubMed Central

    Oelmann, Simon; Nauck, Matthias; Völzke, Henry; Bahls, Martin; Friedrich, Nele

    2016-01-01

    Background/aims Irisin is a myokine, which is mainly inversely associated with the risk for non-communicable diseases. Irisin improves cellular energy metabolism by uncoupling the mitochondrial respiratory chain resulting in increased energy expenditure using lipids. To date potential associations between irisin concentration and lipid profile are poorly understood. Therefore, this investigation aimed to evaluate potential associations between irisin and lipid levels in the general population. Methods Data of 430 men and 537 women from the population-based Study of Health in Pomerania (SHIP-TREND) with available irisin and lipid concentrations were used. Analyses of variance, linear and logistic regression models adjusted for age, HBA1c, waist circumference, physical activity, smoking, alcohol consumption, systolic blood pressure, ALAT were calculated. Results We detected significantly inverse associations between irisin and circulating levels of total [beta coefficient 0.21 (standard error 0.08), p = 0.01], low-density cholesterol [-0.16 (0.07), p = 0.03] and triglycerides [-0.17 (0.08), p = 0.02] for men. Females without lipid lowering medication had an inverse association between irisin and total cholesterol [-0.12 (0.06), p = 0.05]. Further, male subjects with irisin concentrations in the third tertile had an increased odds for elevated low-density cholesterol [odds ratio 1.96 (95% confidence interval 1.07–3.48), p = 0.03) and triglyceride [1.95 (1.09–3.47), p = 0.02] levels, even after exclusion of subjects with lipid lowering medication. In addition, our data revealed an annual rhythm of serum irisin levels with peak levels arise in winter and summer months. Conclusion This is the first investigation to report a significant association between circulating irisin and a favourable lipid profile in the general population. This may infer that higher irisin concentrations are associated with a reduced risk for non-communicable diseases. PMID:27128661

  4. Evaluating the Climate Role of Tropical Cyclones Using an Atmospheric General Circulation Model

    NASA Astrophysics Data System (ADS)

    Winterbottom, H. R.; Pegion, P. J.; Hart, R. E.

    2011-12-01

    A formal assessment and an identification for the global circulation impact of a tropical cyclone (TC) remains in the developmental stages. This area of research was first suggested by Bengtsson et al., [1982], when questions were posed regarding the role of TCs with respect to the poleward transport of heat, moisture, and momentum. To date, much attention has been paid to the role of oceanic heat transport [Emanuel, 2001; Sriver and Huber, 2007; Hart et al., 2007; Liu et al., 2008; Hu and Meehl, 2009]. Fewer studies, however, have identified an explicit role for the TC within the atmosphere, although recent work has begun to quantify the magnitude of that atmospheric footprint from reanalysis datasets [Hart et al., 2007; Schenkel and Hart, 2011]. A recent study by Hart [2011] deduced a statistical relationship between northern hemisphere TC activity (evaluated using both TC count and power dissipation [Emanuel, 2007]) and the subsequent winter climate. Hart [2011] ascertained that there exists a strong (statistical) inverse relationship between the amount of pole-ward TC power-dissipation (e.g., recurving TCs) and the 500-hPa extratropical stationary eddy-temperature flux, and speculated on the physical (and potential nonphysical) explanations for such a relationship. Indeed, the relationship was so strong that it was the most robust predictor of this measure of wind activity amidst all known teleconnection indices. These prior works provide the foundation on which to further explore the TC role in climate. Accordingly, in this study, we diagnose the climatic impact of TCs upon the Earth's general circulation using the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM) and the TC vortex removal procedure discussed by Winterbottom and Chassignet [2011]. A series of experiments with and without TCs will be compared. We will evaluate the mean and transient eddy fluxes as a function of a simulation with TCs and a simulation without. We

  5. Twin Peaks - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The two hills in the distance, approximately one to two kilometers away, have been dubbed the 'Twin Peaks' and are of great interest to Pathfinder scientists as objects of future study. 3D glasses are necessary to identify surface detail. The white areas on the left hill, called the 'Ski Run' by scientists, may have been formed by hydrologic processes.

    The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  6. 3D and beyond

    NASA Astrophysics Data System (ADS)

    Fung, Y. C.

    1995-05-01

    This conference on physiology and function covers a wide range of subjects, including the vasculature and blood flow, the flow of gas, water, and blood in the lung, the neurological structure and function, the modeling, and the motion and mechanics of organs. Many technologies are discussed. I believe that the list would include a robotic photographer, to hold the optical equipment in a precisely controlled way to obtain the images for the user. Why are 3D images needed? They are to achieve certain objectives through measurements of some objects. For example, in order to improve performance in sports or beauty of a person, we measure the form, dimensions, appearance, and movements.

  7. 3D Audio System

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Ames Research Center research into virtual reality led to the development of the Convolvotron, a high speed digital audio processing system that delivers three-dimensional sound over headphones. It consists of a two-card set designed for use with a personal computer. The Convolvotron's primary application is presentation of 3D audio signals over headphones. Four independent sound sources are filtered with large time-varying filters that compensate for motion. The perceived location of the sound remains constant. Possible applications are in air traffic control towers or airplane cockpits, hearing and perception research and virtual reality development.

  8. A study of eddy-mean flow interactions using Eliassen-Palm diagnostics: FGGE SOP-1 data and the NASA GLAS general circulation model compared

    NASA Technical Reports Server (NTRS)

    Baldwin, M. P.; Edmon, H. J., Jr.; Holton, J. R.

    1984-01-01

    Latitude-height cross sections of the Eliassen-Palm (ep) flux, its divergence, the residual mean meridional circulation as well as conventional eddy and mean flow fields are computed using both observational and general circulation model data.

  9. 3D Surgical Simulation

    PubMed Central

    Cevidanes, Lucia; Tucker, Scott; Styner, Martin; Kim, Hyungmin; Chapuis, Jonas; Reyes, Mauricio; Proffit, William; Turvey, Timothy; Jaskolka, Michael

    2009-01-01

    This paper discusses the development of methods for computer-aided jaw surgery. Computer-aided jaw surgery allows us to incorporate the high level of precision necessary for transferring virtual plans into the operating room. We also present a complete computer-aided surgery (CAS) system developed in close collaboration with surgeons. Surgery planning and simulation include construction of 3D surface models from Cone-beam CT (CBCT), dynamic cephalometry, semi-automatic mirroring, interactive cutting of bone and bony segment repositioning. A virtual setup can be used to manufacture positioning splints for intra-operative guidance. The system provides further intra-operative assistance with the help of a computer display showing jaw positions and 3D positioning guides updated in real-time during the surgical procedure. The CAS system aids in dealing with complex cases with benefits for the patient, with surgical practice, and for orthodontic finishing. Advanced software tools for diagnosis and treatment planning allow preparation of detailed operative plans, osteotomy repositioning, bone reconstructions, surgical resident training and assessing the difficulties of the surgical procedures prior to the surgery. CAS has the potential to make the elaboration of the surgical plan a more flexible process, increase the level of detail and accuracy of the plan, yield higher operative precision and control, and enhance documentation of cases. Supported by NIDCR DE017727, and DE018962 PMID:20816308

  10. Martian terrain - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    An area of rocky terrain near the landing site of the Sagan Memorial Station can be seen in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. This image is part of a 3D 'monster' panorama of the area surrounding the landing site.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  11. A comparison between general circulation model simulations using two sea surface temperature datasets for January 1979

    NASA Technical Reports Server (NTRS)

    Ose, Tomoaki; Mechoso, Carlos; Halpern, David

    1994-01-01

    Simulations with the UCLA atmospheric general circulation model (AGCM) using two different global sea surface temperature (SST) datasets for January 1979 are compared. One of these datasets is based on Comprehensive Ocean-Atmosphere Data Set (COADS) (SSTs) at locations where there are ship reports, and climatology elsewhere; the other is derived from measurements by instruments onboard NOAA satellites. In the former dataset (COADS SST), data are concentrated along shipping routes in the Northern Hemisphere; in the latter dataset High Resolution Infrared Sounder (HIRS SST), data cover the global domain. Ensembles of five 30-day mean fields are obtained from integrations performed in the perpetual-January mode. The results are presented as anomalies, that is, departures of each ensemble mean from that produced in a control simulation with climatological SSTs. Large differences are found between the anomalies obtained using COADS and HIRS SSTs, even in the Northern Hemisphere where the datasets are most similar to each other. The internal variability of the circulation in the control simulation and the simulated atmospheric response to anomalous forcings appear to be linked in that the pattern of geopotential height anomalies obtained using COADS SSTs resembles the first empirical orthogonal function (EOF 1) in the control simulation. The corresponding pattern obtained using HIRS SSTs is substantially different and somewhat resembles EOF 2 in the sector from central North America to central Asia. To gain insight into the reasons for these results, three additional simulations are carried out with SST anomalies confined to regions where COADS SSTs are substantially warmer than HIRS SSTs. The regions correspond to warm pools in the northwest and northeast Pacific, and the northwest Atlantic. These warm pools tend to produce positive geopotential height anomalies in the northeastern part of the corresponding oceans. Both warm pools in the Pacific produce large

  12. Fast and Broadband Signal Integrity Analysis of Multiple Vias in Heterogeneous 3D IC and Die-Level Packaging by Using Generalized Foldy-Lax Scattering Method

    NASA Astrophysics Data System (ADS)

    Chang, Xin

    This dissertation proposal is concerned with the use of fast and broadband full-wave electromagnetic methods for modeling high speed interconnects (e.g, vertical vias and horizontal traces) and passive components (e.g, decoupling capacitors) for structures of PCB and packages, in 3D IC, Die-level packaging and SIW based devices, to effectively modeling the designs signal integrity (SI) and power integrity (PI) aspects. The main contributions finished in this thesis is to create a novel methodology, which hybridizes the Foldy-Lax multiple scattering equations based fast full wave method, method of moment (MoM) based 1D technology, modes decoupling based geometry decomposition and cavity modes expansions, to model and simulate the electromagnetic scattering effects for the irregular power/ground planes, multiple vias and traces, for fast and accurate analysis of link level simulation on multilayer electronic structures. For the modeling details, the interior massively-coupled multiple vias problem is modeled most-analytically by using the Foldy-Lax multiple scattering equations. The dyadic Green's functions of the magnetic field are expressed in terms of waveguide modes in the vertical direction and vector cylindrical wave expansions or cavity modes expansions in the horizontal direction, combined with 2D MoM realized by 1D technology. For the incident field of the case of vias in the arbitrarily shaped antipad in finite large cavity/waveguide, the exciting and scattering field coefficients are calculated based on the transformation which converts surface integration of magnetic surface currents in antipad into 1D line integration of surface charges on the vias and on the ground plane. Geometry decomposition method is applied to model and integrate both the vertical and horizontal interconnects/traces in arbitrarily shaped power/ground planes. Moreover, a new form of multiple scattering equations is derived for solving coupling effects among mixed metallic

  13. A 3-D Generalization of the Budyko Framework Captures the Mutual Interdependence Between Long-Term Mean Annual Precipitation, Actual and Potential Evapotranspiration

    NASA Astrophysics Data System (ADS)

    Carmona, A. M.; Poveda, G.

    2012-12-01

    We study the behavior of the 3-D parameter space defined by Φ =PET/P (so-called Aridity Index), Ψ =AET/P, and Ω =AET/PET, where P denotes mean annual precipitation, and PET and AET denote mean annual potential and actual evapotranspiration, respectively. Using information from the CLIMWAT 2.0 database (www.fao.org/nr/water/infores_databases_climwat.html) for P and PET, we estimate AET using both Budyko's and Turc's equations. Our results indicate that the well-known Budyko function that relates Φ vs.Ψ corresponds to a particular bi-dimensional cross-section of a broader coupling existing between Φ, Ψ and Ω (Figure 1a), and in turn of the mutual interdependence between P, PET and AET. The behavior of the three bi-dimensional projections are clearly parameterized by the remaining ortogonal parameter, such that: (i) the relation Φ vs. Ψ is defined by physically consistent varying values of Ω (Figure 1b); (ii) the relation Ω vs. Ψ is defined by physically consistent varying values of the Aridity Index,Φ (Figure 1c), and (iii) the relation Ω vs. Φ is defined by physically consistent varying values of Ψ (Figure 1d). Interestingly, we show that Φ and Ω are related by a power law, Φ~Ω-θ, with scaling exponent θ=1.15 (R2=0.91, n=3420) for the whole world (Figure 1d). Mathematical functions that model the three bi-dimensional projections and the surface defining the interdependence between Φ, Ψ and Ω will be presented. Our results provide a new framework to understand the coupling between the long-term mean annual water and energy balances in river basins, and the hydrological effects brought about by climate change, while taking into account the mutual interdependence between the three non-dimensional parameters Φ, Ψ and Ω, and in turn between P, PET and AET. Figure 1. (a) Three-dimensional rendering of sample values of Φ =PET/P (so-called Aridity Index), Ψ =AET/P, and Ω=AET/PET. Bi-dimensional projections of: (b) relation Φ vs.

  14. Using Green's Functions to initialize and adjust a global, eddying ocean biogeochemistry general circulation model

    NASA Astrophysics Data System (ADS)

    Brix, H.; Menemenlis, D.; Hill, C.; Dutkiewicz, S.; Jahn, O.; Wang, D.; Bowman, K.; Zhang, H.

    2015-11-01

    The NASA Carbon Monitoring System (CMS) Flux Project aims to attribute changes in the atmospheric accumulation of carbon dioxide to spatially resolved fluxes by utilizing the full suite of NASA data, models, and assimilation capabilities. For the oceanic part of this project, we introduce ECCO2-Darwin, a new ocean biogeochemistry general circulation model based on combining the following pre-existing components: (i) a full-depth, eddying, global-ocean configuration of the Massachusetts Institute of Technology general circulation model (MITgcm), (ii) an adjoint-method-based estimate of ocean circulation from the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) project, (iii) the MIT ecosystem model "Darwin", and (iv) a marine carbon chemistry model. Air-sea gas exchange coefficients and initial conditions of dissolved inorganic carbon, alkalinity, and oxygen are adjusted using a Green's Functions approach in order to optimize modeled air-sea CO2 fluxes. Data constraints include observations of carbon dioxide partial pressure (pCO2) for 2009-2010, global air-sea CO2 flux estimates, and the seasonal cycle of the Takahashi et al. (2009) Atlas. The model sensitivity experiments (or Green's Functions) include simulations that start from different initial conditions as well as experiments that perturb air-sea gas exchange parameters and the ratio of particulate inorganic to organic carbon. The Green's Functions approach yields a linear combination of these sensitivity experiments that minimizes model-data differences. The resulting initial conditions and gas exchange coefficients are then used to integrate the ECCO2-Darwin model forward. Despite the small number (six) of control parameters, the adjusted simulation is significantly closer to the data constraints (37% cost function reduction, i.e., reduction in the model-data difference, relative to the baseline simulation) and to independent observations (e.g., alkalinity). The adjusted air-sea gas

  15. Local and Global Views of Systematic Errors of Atmosphere-Ocean General Circulation Models

    NASA Astrophysics Data System (ADS)

    Mechoso, C. Roberto; Wang, Chunzai; Lee, Sang-Ki; Zhang, Liping; Wu, Lixin

    2014-05-01

    Coupled Atmosphere-Ocean General Circulation Models (CGCMs) have serious systematic errors that challenge the reliability of climate predictions. One major reason for such biases is the misrepresentations of physical processes, which can be amplified by feedbacks among climate components especially in the tropics. Much effort, therefore, is dedicated to the better representation of physical processes in coordination with intense process studies. The present paper starts with a presentation of these systematic CGCM errors with an emphasis on the sea surface temperature (SST) in simulations by 22 participants in the Coupled Model Intercomparison Project phase 5 (CMIP5). Different regions are considered for discussion of model errors, including the one around the equator, the one covered by the stratocumulus decks off Peru and Namibia, and the confluence between the Angola and Benguela currents. Hypotheses on the reasons for the errors are reviewed, with particular attention on the parameterization of low-level marine clouds, model difficulties in the simulation of the ocean heat budget under the stratocumulus decks, and location of strong SST gradients. Next the presentation turns to a global perspective of the errors and their causes. It is shown that a simulated weak Atlantic Meridional Overturning Circulation (AMOC) tends to be associated with cold biases in the entire Northern Hemisphere with an atmospheric pattern that resembles the Northern Hemisphere annular mode. The AMOC weakening is also associated with a strengthening of Antarctic bottom water formation and warm SST biases in the Southern Ocean. It is also shown that cold biases in the tropical North Atlantic and West African/Indian monsoon regions during the warm season in the Northern Hemisphere have interhemispheric links with warm SST biases in the tropical southeastern Pacific and Atlantic, respectively. The results suggest that improving the simulation of regional processes may not suffice for a more

  16. The water cycle in the general circulation model of the martian atmosphere

    NASA Astrophysics Data System (ADS)

    Shaposhnikov, D. S.; Rodin, A. V.; Medvedev, A. S.

    2016-03-01

    Within the numerical general-circulation model of the Martian atmosphere MAOAM (Martian Atmosphere: Observation and Modeling), we have developed the water cycle block, which is an essential component of modern general circulation models of the Martian atmosphere. The MAOAM model has a spectral dynamic core and successfully predicts the temperature regime on Mars through the use of physical parameterizations typical of both terrestrial and Martian models. We have achieved stable computation for three Martian years, while maintaining a conservative advection scheme taking into account the water-ice phase transitions, water exchange between the atmosphere and surface, and corrections for the vertical velocities of ice particles due to sedimentation. The studies show a strong dependence of the amount of water that is actively involved in the water cycle on the initial data, model temperatures, and the mechanism of water exchange between the atmosphere and the surface. The general pattern and seasonal asymmetry of the water cycle depends on the size of ice particles, the albedo, and the thermal inertia of the planet's surface. One of the modeling tasks, which results from a comparison of the model data with those of the TES experiment on board Mars Global Surveyor, is the increase in the total mass of water vapor in the model in the aphelion season and decrease in the mass of water ice clouds at the poles. The surface evaporation scheme, which takes into account the turbulent rise of water vapor, on the one hand, leads to the most complete evaporation of ice from the surface in the summer season in the northern hemisphere and, on the other hand, supersaturates the atmosphere with ice due to the vigorous evaporation, which leads to worse consistency between the amount of the precipitated atmospheric ice and the experimental data. The full evaporation of ice from the surface increases the model sensitivity to the size of the polar cap; therefore, the increase in the

  17. A simple hydrologically based model of land surface water and energy fluxes for general circulation models

    NASA Technical Reports Server (NTRS)

    Liang, XU; Lettenmaier, Dennis P.; Wood, Eric F.; Burges, Stephen J.

    1994-01-01

    A generalization of the single soil layer variable infiltration capacity (VIC) land surface hydrological model previously implemented in the Geophysical Fluid Dynamics Laboratory (GFDL) general circulation model (GCM) is described. The new model is comprised of a two-layer characterization of the soil column, and uses an aerodynamic representation of the latent and sensible heat fluxes at the land surface. The infiltration algorithm for the upper layer is essentially the same as for the single layer VIC model, while the lower layer drainage formulation is of the form previously implemented in the Max-Planck-Institut GCM. The model partitions the area of interest (e.g., grid cell) into multiple land surface cover types; for each land cover type the fraction of roots in the upper and lower zone is specified. Evapotranspiration consists of three components: canopy evaporation, evaporation from bare soils, and transpiration, which is represented using a canopy and architectural resistance formulation. Once the latent heat flux has been computed, the surface energy balance is iterated to solve for the land surface temperature at each time step. The model was tested using long-term hydrologic and climatological data for Kings Creek, Kansas to estimate and validate the hydrological parameters, and surface flux data from three First International Satellite Land Surface Climatology Project Field Experiment (FIFE) intensive field campaigns in the summer-fall of 1987 to validate the surface energy fluxes.

  18. The NASA/Ames Mars General Circulation Model: Model Improvements and Comparison with Observations

    NASA Technical Reports Server (NTRS)

    Haberle, R. M.; Hollingsworth, J. L.; Colaprete, A.; Bridger, A. F. C.; McKay, C. P.; Murphy, J. R.; Schaeffer, J.; Freedman, R.; Fonda, Mark (Technical Monitor)

    2003-01-01

    For many years, the NASA/Ames Mars General Circulation Model (GCM) has been built around the UCLA B-grid dynamical core. An attached tracer transport scheme based on the aerosol microphysical model of Toon et al. (1988) provided a tool for studying dust storm transport and feedbacks (Murphy et al., 1995). While we still use a B-grid version of the model, the Ames group is now transitioning to the ARIES/GEOS Goddard C-grid dynamical core (Suarez and Takacs, 1995). The C-grid produces smoother fields when the model top is raised above 50 km, and has a built in transport scheme for an arbitrary number of tracers. All of our transport simulations are now carried out with the C-grid. We have also been updating our physics package. Several years ago we replaced our bulk boundary layer scheme with a level 2 type diffusive scheme, and added a multi-level soil model (Haberle et al., 2000). More recently we replaced our radiation code with a more generalized two-stream code that accounts for aerosol multiple scattering and gaseous absorption. This code gives us much more flexibility in choosing aerosol optical properties and radiatively active gases.

  19. The zonally averaged transport characteristics of the atmosphere as determined by a general circulation model

    NASA Technical Reports Server (NTRS)

    Plumb, R. A.

    1985-01-01

    Two dimensional modeling has become an established technique for the simulation of the global structure of trace constituents. Such models are simpler to formulate and cheaper to operate than three dimensional general circulation models, while avoiding some of the gross simplifications of one dimensional models. Nevertheless, the parameterization of eddy fluxes required in a 2-D model is not a trivial problem. This fact has apparently led some to interpret the shortcomings of existing 2-D models as indicating that the parameterization procedure is wrong in principle. There are grounds to believe that these shortcomings result primarily from incorrect implementations of the predictions of eddy transport theory and that a properly based parameterization may provide a good basis for atmospheric modeling. The existence of these GCM-derived coefficients affords an unprecedented opportunity to test the validity of the flux-gradient parameterization. To this end, a zonally averaged (2-D) model was developed, using these coefficients in the transport parameterization. Results from this model for a number of contrived tracer experiments were compared with the parent GCM. The generally good agreement substantially validates the flus-gradient parameterization, and thus the basic principle of 2-D modeling.

  20. Effects of implementing the Simple Biosphere Model in a general circulation model

    NASA Technical Reports Server (NTRS)

    Sato, N.; Sellers, P. J.; Randall, D. A.; Schneider, E. K.; Shukla, J.

    1989-01-01

    The Simple Biosphere Model (SiB) of Sellers et al., was designed to simulate the interactions between the earth's land surface and the atmosphere by treating the vegetation explicitly and realistically, thereby incorporating the biophysical controls on the exchanges of radiation, momentum, sensible and latent heat between the two systems. This paper describes the steps taken to implement SiB in a modified version of the National Meteorological Center's global spectral general circulation model (GCM) and explores the impact of the implementation on the simulated land surface fluxes and near-surface meteorological conditions. The coupled model (SiB-GCM) was used to produce summer and winter simulations. The same GCM was used with a conventional hydrological model (Ctl-GCM) to produce comparable 'control' summer and winter simulations for comparison. It was found that SiB-GCM produced a more realistic partitioning of energy at the land surface than Ctl-GCM. Generally, SiB-GCM, produced more sensible heat flux and less latent heat flux over vegetated land than did Ctl-GCM and this resulted in a much deeper daytime planetary boundary layer and reduced precipitation rates over the continents in SiB-GCM. In the summer simulation, the 200 mb jet stream was slightly weakened in the SiB-GCM relative to the Ctl-GCM results and analyses made from observations.

  1. The annual cycle of stratospheric water vapor in a general circulation model

    NASA Technical Reports Server (NTRS)

    Mote, Philip W.

    1995-01-01

    The application of general circulation models (GCM's) to stratospheric chemistry and transport both permits and requires a thorough investigation of stratospheric water vapor. The National Center for Atmospheric Research has redesigned its GCM, the Community Climate Model (CCM2), to enable studies of the chemistry and transport of tracers including water vapor; the importance of water vapor to the climate and chemistry of the stratosphere requires that it be better understood in the atmosphere and well represented in the model. In this study, methane is carried as a tracer and converted to water; this simple chemistry provides an adequate representation of the upper stratospheric water vapor source. The cold temperature bias in the winter polar stratosphere, which the CCM2 shares with other GCM's, produces excessive dehydration in the southern hemisphere, but this dry bias can be ameliorated by setting a minimum vapor pressure. The CCM2's water vapor distribution and seasonality compare favorably with observations in many respects, though seasonal variations including the upper stratospheric semiannual oscillation are generally too small. Southern polar dehydration affects midlatitude water vapor mixing ratios by a few tenths of a part per million, mostly after the demise of the vortex. The annual cycle of water vapor in the tropical and northern midlatitude lower stratosphere is dominated by drying at the tropical tropopause. Water vapor has a longer adjustment time than methane and had not reached equilibrium at the end of the 9 years simulated here.

  2. 3D field harmonics

    SciTech Connect

    Caspi, S.; Helm, M.; Laslett, L.J.

    1991-03-30

    We have developed an harmonic representation for the three dimensional field components within the windings of accelerator magnets. The form by which the field is presented is suitable for interfacing with other codes that make use of the 3D field components (particle tracking and stability). The field components can be calculated with high precision and reduced cup time at any location (r,{theta},z) inside the magnet bore. The same conductor geometry which is used to simulate line currents is also used in CAD with modifications more readily available. It is our hope that the format used here for magnetic fields can be used not only as a means of delivering fields but also as a way by which beam dynamics can suggest correction to the conductor geometry. 5 refs., 70 figs.

  3. 6D Interpretation of 3D Gravity

    NASA Astrophysics Data System (ADS)

    Herfray, Yannick; Krasnov, Kirill; Scarinci, Carlos

    2017-02-01

    We show that 3D gravity, in its pure connection formulation, admits a natural 6D interpretation. The 3D field equations for the connection are equivalent to 6D Hitchin equations for the Chern–Simons 3-form in the total space of the principal bundle over the 3-dimensional base. Turning this construction around one gets an explanation of why the pure connection formulation of 3D gravity exists. More generally, we interpret 3D gravity as the dimensional reduction of the 6D Hitchin theory. To this end, we show that any \\text{SU}(2) invariant closed 3-form in the total space of the principal \\text{SU}(2) bundle can be parametrised by a connection together with a 2-form field on the base. The dimensional reduction of the 6D Hitchin theory then gives rise to 3D gravity coupled to a topological 2-form field.

  4. Radiative Impacts of Cloud Heterogeneity and Overlap in an Atmospheric General Circulation Model

    NASA Technical Reports Server (NTRS)

    Oreopoulos, L.; Lee, D.; Sud, Y. C.; Suarez, M. J.

    2012-01-01

    The radiative impacts of introducing horizontal heterogeneity of layer cloud condensate, and vertical overlap of condensate and cloud fraction are examined with the aid of a new radiation package operating in the GEOS-5 Atmospheric General Circulation Model. The impacts are examined in terms of diagnostic top-of-the-atmosphere shortwave (SW) and longwave (LW) cloud radiative effect (CRE) calculations for a range of assumptions and parameter specifications about the overlap. The investigation is conducted for two distinct cloud schemes, the one that comes with the standard GEOS-5 distribution, and another which has been recently used experimentally for its enhanced GEOS-5 distribution, and another which has been recently used experimentally for its enhanced cloud microphysical capabilities; both are coupled to a cloud generator allowing arbitrary cloud overlap specification. We find that cloud overlap radiative impacts are significantly stronger for the operational cloud scheme for which a change of cloud fraction overlap from maximum-random to generalized results to global changes of SW and LW CRE of approximately 4 Watts per square meter, and zonal changes of up to approximately 10 Watts per square meter. This is because of fewer occurrences compared to the other scheme of large layer cloud fractions and of multi-layer situations with large numbers of atmospheric being simultaneously cloudy, conditions that make overlap details more important. The impact on CRE of the details of condensate distribution overlap is much weaker. Once generalized overlap is adopted, both cloud schemes are only modestly sensitive to the exact values of the overlap parameters. We also find that if one of the CRE components is overestimated and the other underestimated, both cannot be driven towards observed values by adjustments to cloud condensate heterogeneity and overlap alone.

  5. A comparative study of rapidly and slowly rotating dynamical regimes in a terrestrial general circulation model

    NASA Technical Reports Server (NTRS)

    Del Genio, Anthony D.; Suozzo, Robert J.

    1987-01-01

    As a preliminary step in the development of a general circulation model for general planetary use, a simplified vesion of thef GISS Model I GCM has been run at various rotation periods to investigate differences between the dynamical regimes of rapidly and slowly rotating planets. To isolate the dynamical processes, the hydrologic cycle is suppressed and the atmosphere is forced with perpetual annual mean solar heating. All other parameters except the rotation period remain fixed at their terrestrial values. Experiments were conducted for rotation periods of 2/3, 1, 2, 4, 8, 16, 64 and 256 days. The results are in qualitative agreement with similar experiments carried out previously with other GCMs and with certain aspects of one Venus GCM simulation. As rotation rate decreases, the energetics shifts from baroclinc to quasi-barotropic when the Rossby radius of deformation reaches planetary scale. The Hadley cell expands poleward and replaces eddies as the primary mode of large-scale heat transport. Associated with this is a poleward shift of the baroclinic zone and jet stream and a reduction of the equator-pole temperature contrast. Midlatitude jet strength peaks at 8 days period, as does the weak positive equatorial zonal wind which occurs at upper levels at all rotation periods. Eddy momentum transport switches from poleward to equatorward at the same period. Tropospheric mean static stability generally increases in the tropics and decreases in midlatitudes as rotation rate decreases, but the global mean static stability is independent of rotation rate. The peak in the eddy kinetic energy spectrum shifts toward lower wavenumbers, reaching wavenumber 1 at a period of 8 days. Implications of these results for the dynamics of Venus and Titan are discussed. Specifically, it is suggested that the extent of low-level convection determines whether the Gierasch mechanism contributes significantly to equatorial superrotation on these planets.

  6. Fast 3-D seismic modeling and prestack depth migration using generalized screen methods. Final report for period January 1, 1998 - December 31, 2000

    SciTech Connect

    Toksoz, M. Nafi

    2001-03-31

    Completed a theoretical analysis of phase screen propagators to answer several critical questions: the existence of a singularity in the Green's function for the case of a zero vertical wavenumber, the stability and accuracy of such propagators, and the effects of backscattering for large contrast heterogeneous media. The theory is based on separating the wavefield into forescattering and backscattering parts. The approach is robust and appropriate for earth structures with high velocity contrast. This theory also resolves the apparent singularity problem that has persisted in generalized screen propagator formulations. With this formulation we studied the effects of the commonly used approximations as a function of the degree of velocity contrast in the media.

  7. Intraoral 3D scanner

    NASA Astrophysics Data System (ADS)

    Kühmstedt, Peter; Bräuer-Burchardt, Christian; Munkelt, Christoph; Heinze, Matthias; Palme, Martin; Schmidt, Ingo; Hintersehr, Josef; Notni, Gunther

    2007-09-01

    Here a new set-up of a 3D-scanning system for CAD/CAM in dental industry is proposed. The system is designed for direct scanning of the dental preparations within the mouth. The measuring process is based on phase correlation technique in combination with fast fringe projection in a stereo arrangement. The novelty in the approach is characterized by the following features: A phase correlation between the phase values of the images of two cameras is used for the co-ordinate calculation. This works contrary to the usage of only phase values (phasogrammetry) or classical triangulation (phase values and camera image co-ordinate values) for the determination of the co-ordinates. The main advantage of the method is that the absolute value of the phase at each point does not directly determine the coordinate. Thus errors in the determination of the co-ordinates are prevented. Furthermore, using the epipolar geometry of the stereo-like arrangement the phase unwrapping problem of fringe analysis can be solved. The endoscope like measurement system contains one projection and two camera channels for illumination and observation of the object, respectively. The new system has a measurement field of nearly 25mm × 15mm. The user can measure two or three teeth at one time. So the system can by used for scanning of single tooth up to bridges preparations. In the paper the first realization of the intraoral scanner is described.

  8. 'Diamond' in 3-D

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 3-D, microscopic imager mosaic of a target area on a rock called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  9. Prominent rocks - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Many prominent rocks near the Sagan Memorial Station are featured in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. Wedge is at lower left; Shark, Half-Dome, and Pumpkin are at center. Flat Top, about four inches high, is at lower right. The horizon in the distance is one to two kilometers away.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  10. The implementation and validation of improved land-surface hydrology in an atmospheric general circulation model

    NASA Technical Reports Server (NTRS)

    Johnson, Kevin D.; Entekhabi, Dara; Eagleson, Peter S.

    1993-01-01

    New land-surface hydrologic parameterizations are implemented into the NASA Goddard Institute for Space Studies (GISS) General Circulation Model (GCM). These parameterizations are: 1) runoff and evapotranspiration functions that include the effects of subgrid-scale spatial variability and use physically based equations of hydrologic flux at the soil surface and 2) a realistic soil moisture diffusion scheme for the movement of water and root sink in the soil column. A one-dimensional climate model with a complete hydrologic cycle is used to screen the basic sensitivities of the hydrological parameterizations before implementation into the full three-dimensional GCM. Results of the final simulation with the GISS GCM and the new land-surface hydrology indicate that the runoff rate, especially in the tropics, is significantly improved. As a result, the remaining components of the heat and moisture balance show similar improvements when compared to observations. The validation of model results is carried from the large global (ocean and land-surface) scale to the zonal, continental, and finally the regional river basin scales.

  11. Three-dimensional computer model for the atmospheric general circulation experiment

    NASA Technical Reports Server (NTRS)

    Roberts, G. O.

    1984-01-01

    An efficient, flexible, three-dimensional, hydrodynamic, computer code has been developed for a spherical cap geometry. The code will be used to simulate NASA's Atmospheric General Circulation Experiment (AGCE). The AGCE is a spherical, baroclinic experiment which will model the large-scale dynamics of our atmosphere; it has been proposed to NASA for future Spacelab flights. In the AGCE a radial dielectric body force will simulate gravity, with hot fluid tending to move outwards. In order that this force be dominant, the AGCE must be operated in a low gravity environment such as Spacelab. The full potential of the AGCE will only be realized by working in conjunction with an accurate computer model. Proposed experimental parameter settings will be checked first using model runs. Then actual experimental results will be compared with the model predictions. This interaction between experiment and theory will be very valuable in determining the nature of the AGCE flows and hence their relationship to analytical theories and actual atmospheric dynamics.

  12. Variation of the global electric circuit and Ionospheric potential in a general circulation model

    NASA Astrophysics Data System (ADS)

    Mareev, E. A.; Volodin, E. M.

    2014-12-01

    A general circulation model of the atmosphere and ocean INMCM4.0 (Institute of Numerical Mathematics Coupled Model) is used for modeling the global electric circuit short-time variability and long-term evolution. The ionospheric potential parameterization is proposed which takes into account quasi-stationary currents of electrified clouds (including thunderstorms) as principal contributors into the DC global circuit. The diurnal, seasonal, and interannual variations of the ionospheric potential (IP) are modeled and compared with available data. Numerical simulations suggest that the IP decreases in the mean with the global warming due to increasing greenhouse gas emission (by about 10% during the 21st century if the Representative Concentration Pathway 8.5 Wm-2 scenario is assumed). At the same time the lightning flash rate increases with global warming by about 5 fl/s per degree. Interannual IP variability is low and does not exceed 1% of the mean value, being tightly correlated with the mean sea surface temperature in the Pacific Ocean (El Niño area).

  13. Hurricane Forecasting with the High-resolution NASA Finite-volume General Circulation Model

    NASA Technical Reports Server (NTRS)

    Atlas, R.; Reale, O.; Shen, B.-W.; Lin, S.-J.; Chern, J.-D.; Putman, W.; Lee, T.; Yeh, K.-S.; Bosilovich, M.; Radakovich, J.

    2004-01-01

    A high-resolution finite-volume General Circulation Model (fvGCM), resulting from a development effort of more than ten years, is now being run operationally at the NASA Goddard Space Flight Center and Ames Research Center. The model is based on a finite-volume dynamical core with terrain-following Lagrangian control-volume discretization and performs efficiently on massive parallel architectures. The computational efficiency allows simulations at a resolution of a quarter of a degree, which is double the resolution currently adopted by most global models in operational weather centers. Such fine global resolution brings us closer to overcoming a fundamental barrier in global atmospheric modeling for both weather and climate, because tropical cyclones and even tropical convective clusters can be more realistically represented. In this work, preliminary results of the fvGCM are shown. Fifteen simulations of four Atlantic tropical cyclones in 2002 and 2004 are chosen because of strong and varied difficulties presented to numerical weather forecasting. It is shown that the fvGCM, run at the resolution of a quarter of a degree, can produce very good forecasts of these tropical systems, adequately resolving problems like erratic track, abrupt recurvature, intense extratropical transition, multiple landfall and reintensification, and interaction among vortices.

  14. El Nino-southern oscillation simulated in an MRI atmosphere-ocean coupled general circulation model

    SciTech Connect

    Nagai, T.; Tokioka, T.; Endoh, M.; Kitamura, Y. )

    1992-11-01

    A coupled atmosphere-ocean general circulation model (GCM) was time integrated for 30 years to study interannual variability in the tropics. The atmospheric component is a global GCM with 5 levels in the vertical and 4[degrees]latitude X 5[degrees] longitude grids in the horizontal including standard physical processes (e.g., interactive clouds). The oceanic component is a GCM for the Pacific with 19 levels in the vertical and 1[degrees]x 2.5[degrees] grids in the horizontal including seasonal varying solar radiation as forcing. The model succeeded in reproducing interannual variations that resemble the El Nino-Southern Oscillation (ENSO) with realistic seasonal variations in the atmospheric and oceanic fields. The model ENSO cycle has a time scale of approximately 5 years and the model El Nino (warm) events are locked roughly in phase to the seasonal cycle. The cold events, however, are less evident in comparison with the El Nino events. The time scale of the model ENSO cycle is determined by propagation time of signals from the central-eastern Pacific to the western Pacific and back to the eastern Pacific. Seasonal timing is also important in the ENSO time scale: wind anomalies in the central-eastern Pacific occur in summer and the atmosphere ocean coupling in the western Pacific operates efficiently in the first half of the year.

  15. Global environmental effects of impact-generated aerosols: Results from a general circulation model, revision 1

    NASA Technical Reports Server (NTRS)

    Covey, Curt; Ghan, Steven J.; Walton, John J.; Weissman, Paul R.

    1989-01-01

    Interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet would lead to substantial land surface cooling, according to our three-dimensional atmospheric general circulation model (GCM). This result is qualitatively similar to conclusions drawn from an earlier study that employed a one-dimensional atmospheric model, but in the GCM simulation the heat capacity of the oceans substantially mitigates land surface cooling, an effect that one-dimensional models cannot quantify. On the other hand, the low heat capacity of the GCM's land surface allows temperatures to drop more rapidly in the initial stage of cooling than in the one-dimensional model study. These two differences between three-dimensional and one-dimensional model simulations were noted previously in studies of nuclear winter; GCM-simulated climatic changes in the Alvarez-inspired scenario of asteroid/comet winter, however, are more severe than in nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on earth. Impacts of smaller objects could also lead to dramatic, though less severe, climatic changes, according to our GCM. Our conclusion is that it is difficult to imagine an asteroid or comet impact leading to anything approaching complete global freezing, but quite reasonable to assume that impacts at the Alvarez level, or even smaller, dramatically alter the climate in at least a patchy sense.

  16. Global environmental effects of impact-generated aerosols: Results from a general circulation model

    NASA Technical Reports Server (NTRS)

    Covey, Curt; Ghan, Steven J.; Walton, John J.; Weissman, Paul R.

    1989-01-01

    Interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet would lead to substantial land surface cooling, according to the three-dimensional atmospheric general circulation model (GCM). This result is qualitatively similar to conclusions drawn from an earlier study that employed a one-dimensional atmospheric model, but in the GCM simulation the heat capacity of the oceans, not included in the one-dimensional model, substantially mitigates land surface cooling. On the other hand, the low heat capacity of the GCM's land surface allows temperatures to drop more rapidly in the initial stages of cooling than in the one-dimensional model study. GCM-simulated climatic changes in the scenario of asteroid/comet winter are more severe than in nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on earth. Impacts of smaller objects could also lead to dramatic, though of course less severe, climatic changes, according to the GCM. An asteroid or comet impact would not lead to anything approaching complete global freezing, but quite reasonable to assume that impacts would dramatically alter the climate in at least a patchy sense.

  17. The implementation and validation of improved landsurface hydrology in an atmospheric general circulation model

    NASA Technical Reports Server (NTRS)

    Johnson, Kevin D.; Entekhabi, Dara; Eagleson, Peter S.

    1991-01-01

    Landsurface hydrological parameterizations are implemented in the NASA Goddard Institute for Space Studies (GISS) General Circulation Model (GCM). These parameterizations are: (1) runoff and evapotranspiration functions that include the effects of subgrid scale spatial variability and use physically based equations of hydrologic flux at the soil surface, and (2) a realistic soil moisture diffusion scheme for the movement of water in the soil column. A one dimensional climate model with a complete hydrologic cycle is used to screen the basic sensitivities of the hydrological parameterizations before implementation into the full three dimensional GCM. Results of the final simulation with the GISS GCM and the new landsurface hydrology indicate that the runoff rate, especially in the tropics is significantly improved. As a result, the remaining components of the heat and moisture balance show comparable improvements when compared to observations. The validation of model results is carried from the large global (ocean and landsurface) scale, to the zonal, continental, and finally the finer river basin scales.

  18. Thermosphere-Ionosphere-Electrodynamics General Circulation Model for the Ionospheric Connection Explorer: TIEGCM-ICON

    NASA Astrophysics Data System (ADS)

    Maute, Astrid

    2017-04-01

    The NASA Ionospheric Connection explorer (ICON) will study the coupling between the thermosphere and ionosphere at low- and mid-latitudes by measuring the key parameters. The ICON mission will also employ numerical modeling to support the interpretation of the observations, and examine the importance of different vertical coupling mechanisms by conducting numerical experiments. One of these models is the Thermosphere-Ionosphere-Electrodynamics General Circulation Model-ICON (TIEGCM-ICON) which will be driven by tidal perturbations derived from ICON observations using the Hough Mode Extension method (HME) and at high latitude by ion convection and auroral particle precipitation patterns from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE). The TIEGCM-ICON will simulate the thermosphere-ionosphere (TI) system during the period of the ICON mission. In this report the TIEGCM-ICON is introduced, and the focus is on examining the effect of the lower boundary on the TI-system to provide some guidance for interpreting future ICON model results.

  19. Modeling of submarine melting in Petermann Fjord, Northwestern Greenland using an ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Cai, C.; Rignot, E. J.; Xu, Y.; An, L.

    2013-12-01

    Basal melting of the floating tongue of Petermann Glacier, in northwestern Greenland is by far the largest process of mass ablation. Melting of the floating tongue is controlled by the buoyancy of the melt water plume, the pressure-dependence of the melting point of sea ice, and the mixing of warm subsurface water with fresh buoyant subglacial discharge. In prior simulations of this melting process, the role of subglacial discharge has been neglected because in similar configurations (floating ice shelves) in the Antarctic, surface runoff is negligible; this is however not true in Greenland. Here, we use the Mass Institute of Technology general circulation model (MITgcm) at a high spatial resolution (10 m x 10 m) to simulate the melting process of the ice shelf in 2-D. the model is constrained by ice shelf bathymetry and ice thickness from NASA Operation IceBridge, ocean temperature/salinity data from Johnson et al. (2011), and subglacial discharge estimated from output products of the Regional Atmospheric Climate Model (RACMO). We compare the results obtained in winter (no runoff) with summer, and the sensitivity of the results to thermal forcing from the ocean, and to the magnitude of subglacial runoff. We conclude on the impact of the ocean and surface melting on the melting regime of the floating ice tongue of Petermann. This work is performed under a contract with NASA Cryosphere Program.

  20. Evaluating Parameterizations in General Circulation Models: Climate Simulation Meets Weather Prediction

    SciTech Connect

    Phillips, T J; Potter, G L; Williamson, D L; Cederwall, R T; Boyle, J S; Fiorino, M; Hnilo, J J; Olson, J G; Xie, S; Yio, J J

    2004-05-06

    To significantly improve the simulation of climate by general circulation models (GCMs), systematic errors in representations of relevant processes must first be identified, and then reduced. This endeavor demands that the GCM parameterizations of unresolved processes, in particular, should be tested over a wide range of time scales, not just in climate simulations. Thus, a numerical weather prediction (NWP) methodology for evaluating model parameterizations and gaining insights into their behavior may prove useful, provided that suitable adaptations are made for implementation in climate GCMs. This method entails the generation of short-range weather forecasts by a realistically initialized climate GCM, and the application of six-hourly NWP analyses and observations of parameterized variables to evaluate these forecasts. The behavior of the parameterizations in such a weather-forecasting framework can provide insights on how these schemes might be improved, and modified parameterizations then can be tested in the same framework. In order to further this method for evaluating and analyzing parameterizations in climate GCMs, the U.S. Department of Energy is funding a joint venture of its Climate Change Prediction Program (CCPP) and Atmospheric Radiation Measurement (ARM) Program: the CCPP-ARM Parameterization Testbed (CAPT). This article elaborates the scientific rationale for CAPT, discusses technical aspects of its methodology, and presents examples of its implementation in a representative climate GCM.

  1. Application of Local Discretization Methods in the NASA Finite-Volume General Circulation Model

    NASA Technical Reports Server (NTRS)

    Yeh, Kao-San; Lin, Shian-Jiann; Rood, Richard B.

    2002-01-01

    We present the basic ideas of the dynamics system of the finite-volume General Circulation Model developed at NASA Goddard Space Flight Center for climate simulations and other applications in meteorology. The dynamics of this model is designed with emphases on conservative and monotonic transport, where the property of Lagrangian conservation is used to maintain the physical consistency of the computational fluid for long-term simulations. As the model benefits from the noise-free solutions of monotonic finite-volume transport schemes, the property of Lagrangian conservation also partly compensates the accuracy of transport for the diffusion effects due to the treatment of monotonicity. By faithfully maintaining the fundamental laws of physics during the computation, this model is able to achieve sufficient accuracy for the global consistency of climate processes. Because the computing algorithms are based on local memory, this model has the advantage of efficiency in parallel computation with distributed memory. Further research is yet desirable to reduce the diffusion effects of monotonic transport for better accuracy, and to mitigate the limitation due to fast-moving gravity waves for better efficiency.

  2. Modeling of clouds and radiation for developing parameterizations for general circulation models. Annual report, 1994

    SciTech Connect

    1994-12-31

    We are using a hierarchy of numerical models of cirrus and stratus clouds and radiative transfer to improve the reliability of general circulation models. Our detailed cloud microphysical model includes all of the physical processes believed to control the lifecycle of liquid and ice clouds in the troposphere. In our one-dimensional cirrus studies, we find that the ice crystal number and size in cirrus clouds are not very sensitive to the number of condensation nuclei which are present. We have compared our three-dimensional meoscale simulations of cirrus clouds with radar, lidar satellite and other observations of water vapor and cloud fields and find that the model accurately predicts the characteristics of a cirrus cloud system. The model results reproduce several features detected by remote sensing (lidar and radar) measurements, including the appearance of the high cirrus cloud at about 15 UTC and the thickening of the cloud at 20 UTC. We have developed a new parameterizations for production of ice crystals based on the detailed one-dimensional cloud model, and are presently testing the parameterization in three-dimensional simulations of the FIRE-II November 26 case study. We have analyzed NWS radiosonde humidity data from FIRE and ARM and found errors, biases, and uncertainties in the conversion of the sensed resistance to humidity.

  3. Modeling of clouds and radiation for developing parameterizations for general circulation models. Annual report, 1995

    SciTech Connect

    Toon, O.B.; Westphal, D.L.

    1996-07-01

    We have used a hierarchy of numerical models for cirrus and stratus clouds and for radiative transfer to improve the reliability of general circulation models. Our detailed cloud microphysical model includes all of the physical processes believed to control the lifecycles of liquid and ice clouds in the troposphere. We have worked on specific GCM parameterizations for the radiative properties of cirrus clouds, making use of a mesocale model as the test-bed for the parameterizations. We have also modeled cirrus cloud properties with a detailed cloud physics model to better understand how the radiatively important properties of cirrus are controlled by their environment. We have used another cloud microphysics model to investigate of the interactions between aerosols and clouds. This work is some of the first to follow the details of interactions between aerosols and cloud droplets and has shown some unexpected relations between clouds and aerosols. We have also used line-by- line radiative transfer results verified with ARM data, to derive a GCMS.

  4. Diagnostic study of climate feedback processes in atmospheric general circulation models

    SciTech Connect

    Zhang, M.H.; Cess, R.D.; Hack, J.J.; Kiehl, J.T.

    1994-03-20

    A method is proposed to diagnose climate feedbacks of water vapor, temperature lapse-rate, and cloud variations in atmospheric general circulation models. It is then applied to study differences in sensitivity of the National Center for Atmospheric Research community climate model (CCM2) and two hybrid versions of CCM2 with different cumulus-convection schemes. Water vapor feedback and temperature lapse-rate feedback differ among the models due to different efficiencies of heat and moisture transport by cumulus convections. A large compensation occurs between water vapor feedback and temperature lapse-rate feedback. This leads to similar clear-sky sensitivities in the models. Cloud-radiative feedback is negative in CCM2 with a {delta}SST climate change due to the vigorous cumulus-convective scheme. Stronger convection warms the upper troposphere and reduces its cloudiness more, resulting in negative longwave cloud-radiative feedback. In models where a moist-adiabatic-adjustment scheme and then a decoupling of the atmospheric boundary layer are subsequently used, intensity of cumulus convection is successively reduced and cloud-radiative feedback changes to either neutral or positive. 31 refs., 21 figs., 21 tabs.

  5. A hierarchical framework for coupling surface fluxes to atompsheric general circulation models: The homogeneity test

    SciTech Connect

    Miller, N.L.

    1993-01-01

    The atmosphere and the biosphere are inherently coupled to one another. Atmospheric surface state variables such as temperature, winds, water vapor, precipitation, and radiation control biophysical, biogeochemical, and ecological processes at the surface and subsurface. At the same time, surface fluxes of momentum, moisture, heat, and trace gases act as time-dependent boundary conditions providing feedback on atmospheric processes. To understand such phenomena, a coupled set of interactive models is required. Costs are still prohibitive for computing surface/subsurface fluxes directly for medium-resolution atmospheric general circulation models (AGCMs), but a technique has been developed for testing large-scale homogeneity and accessing surface parameterizations and models to reduce this computational cost and maintain accuracy. This modeling system potentially bridges the observed spatial and temporal ranges yet allows the incorporation of necessary details about individual ecological community types or biomes and simulates the net momentum, heat, moisture, and trace gas fluxes. This suite of coupled models is defined here as the hierarchical systems flux scheme (HSFS).

  6. A hierarchical framework for coupling surface fluxes to atompsheric general circulation models: The homogeneity test

    SciTech Connect

    Miller, N.L.

    1993-12-31

    The atmosphere and the biosphere are inherently coupled to one another. Atmospheric surface state variables such as temperature, winds, water vapor, precipitation, and radiation control biophysical, biogeochemical, and ecological processes at the surface and subsurface. At the same time, surface fluxes of momentum, moisture, heat, and trace gases act as time-dependent boundary conditions providing feedback on atmospheric processes. To understand such phenomena, a coupled set of interactive models is required. Costs are still prohibitive for computing surface/subsurface fluxes directly for medium-resolution atmospheric general circulation models (AGCMs), but a technique has been developed for testing large-scale homogeneity and accessing surface parameterizations and models to reduce this computational cost and maintain accuracy. This modeling system potentially bridges the observed spatial and temporal ranges yet allows the incorporation of necessary details about individual ecological community types or biomes and simulates the net momentum, heat, moisture, and trace gas fluxes. This suite of coupled models is defined here as the hierarchical systems flux scheme (HSFS).

  7. Evaluation of tropical cloud regimes in observations and a general circulation model

    NASA Astrophysics Data System (ADS)

    Chen, Yonghua; Del Genio, Anthony D.

    2009-02-01

    Tropical cloud regimes defined by cluster analysis of International Satellite Cloud Climatology Project (ISCCP) cloud top pressure (CTP)-optical thickness distributions and ISCCP-like Goddard Institute for Space Studies (GISS) general circulation model (GCM) output are analyzed in this study. The observations are evaluated against radar-lidar cloud-top profiles from the atmospheric radiation measurement (ARM) Program active remote sensing of cloud layers (ARSCL) product at two tropical locations and by placing them in the dynamical context of the Madden-Julian oscillation (MJO). ARSCL highest cloud-top profiles indicate that differences among some of the six ISCCP regimes may not be as prominent as suggested by ISCCP at the ARM tropical sites. An experimental adjustment of the ISCCP CTPs to produce cloud-top height profiles consistent with ARSCL eliminates the independence between those regimes. Despite these ambiguities, the ISCCP regime evolution over different phases of the MJO is consistent with existing MJO mechanisms, but with a greater mix of cloud types in each phase than is usually envisioned. The GISS Model E GCM produces two disturbed and two suppressed regimes when vertical convective condensate transport is included in the model’s cumulus parameterization. The primary model deficiencies are the absence of an isolated cirrus regime, a lack of mid-level cloud relative to ARSCL, and a tendency for occurrences of specific parameterized processes such as deep and shallow convection and stratiform low cloud formation to not be associated preferentially with any single cloud regime.

  8. The GEOS-5 Atmospheric General Circulation Model: Mean Climate and Development from MERRA to Fortuna

    NASA Technical Reports Server (NTRS)

    Molod, Andrea; Takacs, Lawrence; Suarez, Max; Bacmeister, Julio; Song, In-Sun; Eichmann, Andrew

    2012-01-01

    This report is a documentation of the Fortuna version of the GEOS-5 Atmospheric General Circulation Model (AGCM). The GEOS-5 AGCM is currently in use in the NASA Goddard Modeling and Assimilation Office (GMAO) for simulations at a wide range of resolutions, in atmosphere only, coupled ocean-atmosphere, and data assimilation modes. The focus here is on the development subsequent to the version that was used as part of NASA s Modern-Era Retrospective Analysis for Research and Applications (MERRA). We present here the results of a series of 30-year atmosphere-only simulations at different resolutions, with focus on the behavior of the 1-degree resolution simulation. The details of the changes in parameterizations subsequent to the MERRA model version are outlined, and results of a series of 30-year, atmosphere-only climate simulations at 2-degree resolution are shown to demonstrate changes in simulated climate associated with specific changes in parameterizations. The GEOS-5 AGCM presented here is the model used for the GMAO s atmosphere-only and coupled CMIP-5 simulations.

  9. MJO prediction skill, predictability, and teleconnection impacts in the Beijing Climate Center Atmospheric General Circulation Model

    NASA Astrophysics Data System (ADS)

    Wu, Jie; Ren, Hong-Li; Zuo, Jinqing; Zhao, Chongbo; Chen, Lijuan; Li, Qiaoping

    2016-09-01

    This study evaluates performance of Madden-Julian oscillation (MJO) prediction in the Beijing Climate Center Atmospheric General Circulation Model (BCC_AGCM2.2). By using the real-time multivariate MJO (RMM) indices, it is shown that the MJO prediction skill of BCC_AGCM2.2 extends to about 16-17 days before the bivariate anomaly correlation coefficient drops to 0.5 and the root-mean-square error increases to the level of the climatological prediction. The prediction skill showed a seasonal dependence, with the highest skill occurring in boreal autumn, and a phase dependence with higher skill for predictions initiated from phases 2-4. The results of the MJO predictability analysis showed that the upper bounds of the prediction skill can be extended to 26 days by using a single-member estimate, and to 42 days by using the ensemble-mean estimate, which also exhibited an initial amplitude and phase dependence. The observed relationship between the MJO and the North Atlantic Oscillation was accurately reproduced by BCC_AGCM2.2 for most initial phases of the MJO, accompanied with the Rossby wave trains in the Northern Hemisphere extratropics driven by MJO convection forcing. Overall, BCC_AGCM2.2 displayed a significant ability to predict the MJO and its teleconnections without interacting with the ocean, which provided a useful tool for fully extracting the predictability source of subseasonal prediction.

  10. Secular Trends and Climate Drift in Coupled Ocean-Atmosphere General Circulation Models

    SciTech Connect

    Covey, C C; Gleckler, P J; Phillips, T J; Bader, D C

    2004-11-23

    Coupled ocean-atmosphere general circulation models (coupled GCMs) with interactive sea ice are the primary tool for investigating possible future global warming and numerous other issues in climate science. A long-standing problem with such models is that when different components of the physical climate system are linked together, the simulated climate can drift away from observations unless constrained by ad hoc adjustments to interface fluxes. However, eleven modern coupled GCMs--including three that do not employ flux adjustments--behave much better in this respect than the older generation of models. Surface temperature trends in control run simulations (with external climate forcing such as solar brightness and atmospheric carbon dioxide held constant) are small compared with observed trends, which include 20th century climate change due to both anthropogenic and natural factors. Sea ice changes in the models are dominated by interannual variations. Deep ocean temperature and salinity trends are small enough for model control runs to extend over 1000 simulated years or more, but trends in some regions, most notably the Arctic, are inconsistent among the models and may be problematic.

  11. The annual pressure cycle on Mars: Results from the LMD Martian atmospheric general circulation model

    NASA Technical Reports Server (NTRS)

    Hourdin, Frederic; Forget, Francois; Talagrand, O.

    1993-01-01

    We have been developing a General Circulation Model (GCM) of the martian atmosphere since 1989. The model has been described rather extensively elsewhere and only the main characteristics are given here. The dynamical part of the model, adapted from the LMD terrestrial climate model, is based on a finite-difference formulation of the classical 'primitive equations of meteorology.' The radiative transfer code includes absorption and emission by CO2 (carefully validated by comparison to line-by-line calculations) and dust in the thermal range and absorption and scattering by dust in the visible range. Other physical parameterizations are included: modeling of vertical turbulent mixing, dry convective adjustment (in order to prevent vertical unstable temperature profiles), and a multilayer model of the thermal conduction in the soil. Finally, the condensation-sublimation of CO2 is introduced through specification of a pressure-dependent condensation temperature. The atmospheric and surface temperatures are prevented from falling below this critical temperature by condensation and direct precipitation onto the surface of atmospheric CO2. The only prespecified spatial fields are the surface thermal inertia, albedo, and topography.

  12. Spatial and Temporal Variation of Torrential Rain over Northwest China and General Circulation Anomaly in Summer

    NASA Astrophysics Data System (ADS)

    ZHAO, Qingyun; YANG, Guiming

    2015-04-01

    The features of spatial and temporal variation of torrential rain over Northwest China and general circulation were analyzed, by using the daily precipitation observed at 248 stations and NCEP/NCAR reanalysis data from 1981 to 2010. The results show that torrential rain occurred in Shanxi province, southeast of Gansu province and southeast of Ningxia Hui Autonomous Region. The frequency of torrential rain reduced gradually from southeast to northwest, and had obvious inter-annual difference . Torrential rain mainly occurred between July and August each year, the number of torrential rain in July and August contributed 64% to the whole year, with the highest in July and sub-high in August. The number of regional torrential rain was most numerous in late July. The regional torrential rain in Summer was greater than normal when the western Pacific subtropical high was strong, west ridge point reached 110° E and low pressure systems constantly appeared at middle and high latitudes area of Asia. The south air at low level (700hPa) stretched northward to the east part of northwest, and transported the vapor to the region, and encountered northwest air at about 35° N. The regional torrential rain in Summer was less than normal when the western Pacific subtropical high was weak, far away from the mainland China, and the high pressure systems constantly appeared at high latitudes area of Asia, while the north air was dominated over the east part of northwest.

  13. Martian atmospheric gravity waves simulated by a high-resolution general circulation model

    NASA Astrophysics Data System (ADS)

    Kuroda, Takeshi; Yiǧit, Erdal; Medvedev, Alexander S.; Hartogh, Paul

    2016-07-01

    Gravity waves (GWs) significantly affect temperature and wind fields in the Martian middle and upper atmosphere. They are also one of the observational targets of the MAVEN mission. We report on the first simulations with a high-resolution general circulation model (GCM) and present a global distributions of small-scale GWs in the Martian atmosphere. The simulated GW-induced temperature variances are in a good agreement with available radio occultation data in the lower atmosphere between 10 and 30 km. For the northern winter solstice, the model reveals a latitudinal asymmetry with stronger wave generation in the winter hemisphere and two distinctive sources of GWs: mountainous regions and the meandering winter polar jet. Orographic GWs are filtered upon propagating upward, and the mesosphere is primarily dominated by harmonics with faster horizontal phase velocities. Wave fluxes are directed mainly against the local wind. GW dissipation in the upper mesosphere generates a body force per unit mass of tens of m s^{-1} per Martian solar day (sol^{-1}), which tends to close the simulated jets. The results represent a realistic surrogate for missing observations, which can be used for constraining GW parameterizations and validating GCMs.

  14. An Infrared Radiative Transfer Parameterization For A Venus General Circulation Model

    NASA Astrophysics Data System (ADS)

    Eymet, Vincent; Fournier, R.; Lebonnois, S.; Bullock, M. A.; Dufresne, J.; Hourdin, F.

    2006-09-01

    A new 3-dimensional General Circulation Model (GCM) of Venus'atmosphere is curently under development at the Laboratoire de Meteorologie Dynamique, in the context of the Venus-Express mission. Special attention was devoted to the parameterization of infrared radiative transfer: this parameterization has to be both very fast and sufficiently accurate in order to provide valid results over extented periods of time. We have developped at the Laboratoire d'Energetique a Monte-Carlo code for computing reference radiative transfer results for optically thick inhomogeneous scattering planetary atmospheres over the IR spectrum. This code (named KARINE) is based on a Net-Exchange Rates formulation, and uses a k-distribution spectral model. The Venus spectral data, that was compiled at the Southwest Research Institute, accounts for gaseous absorption and scattering, typical clouds absorption and scattering, as well as CO2 and H2O absorption continuums. We will present the Net-Exchange Rates matrix that was computed using the Monte-Carlo approach. We will also show how this matrix has been used in order to produce a first-order radiative transfer parameterization that is used in the LMD Venus GCM. In addition, we will present how the proposed radiative transfer model was used in a simple convective-radiative equilibrium model in order to reproduce the main features of Venus' temperature profile.

  15. Modeling and analysis of aerosol processes in an interactive chemistry general circulation model

    NASA Astrophysics Data System (ADS)

    Verma, Sunita; Boucher, O.; Reddy, M. S.; Upadhyaya, H. C.; Le van, P.; Binkowski, F. S.; Sharma, O. P.

    2007-02-01

    An "online" aerosol dynamics and chemistry module is included in the Laboratoire de Météorologie Dynamique general circulation model (LMDZ), so that the chemical species are advected at each dynamical time step and evolve through chemical and physical processes that have been parameterized consistently with the meteorology. These processes include anthropogenic and biogenic emissions, over 50 gas/aqueous phase chemical reactions, transport due to advection, vertical diffusion and convection, dry deposition and wet scavenging. We have introduced a size-resolved representation of aerosols which undergo various processes such as coagulation, nucleation and dry and wet scavenging. The model considers 16 prognostic tracers: water vapor, liquid water, dimethyl sulfide (DMS), hydrogen sulfide (H2S), dimethyl sulphoxide (DMSO), methanesulphonic acid (MSA), sulfur dioxide (SO2), nitrogen oxides (NOX), carbon monoxide (CO), nitric acid (HNO3), ozone (O3), hydrogen peroxide (H2O2), sulfate mass and number for Aitken and accumulation modes. The scheme accounts for two-way interactions between tropospheric chemistry and aerosols. The oxidants and chemical species fields that represent the sulfate aerosol formation are evolved interactively with the model dynamics. A detailed description on the coupled climate-chemistry interactive module is presented with the evaluation of chemical species in winter and summer seasons. Aqueous phase reactions in cloud accounted for 71% of sulfate production rate, while only 45% of the sulfate burden in the troposphere is derived from in-cloud oxidation.

  16. GCM (general circulation model)-data intercomparison: The good news and the bad

    SciTech Connect

    Grotch, S.L.

    1990-09-01

    General circulation models (GCMs) are being actively used to assess possible climate change due to increasing greenhouse gas concentrations. Because such simulations provide detailed climatic predictions at a wide range of scales, they are of particular interest to those making regional assessments of climatic change. It is especially important that workers using the results of such simulations be aware of some of the limitations of these results. In this study some of the positive results from these model simulations will be shown and some of the deficiencies will also be highlighted. Following an introductory section describing the nature of GCM climate simulations the issue of the spatial scales of such simulations is examined. A comparison of the results of seven GCM simulations of the current climate and the predictions of these models for the changes due to a doubling of CO{sub 2} will be discussed. In these intercomparisons, the spatial scale over which the results are compared varies from global to zonal (longitudinally averaged at a given latitude) to individual slices through the data along specified latitudes or longitudes. Finally, the dangers and pitfalls of relying on simple averages will be highlighted. 19 refs., 9 figs., 1 tab.

  17. The extratropical 40-day oscillation in the UCLA general circulation model. Part 1: Atmospheric angular momentum

    NASA Technical Reports Server (NTRS)

    Marcus, S. L.; Ghil, M.; Dickey, J. O.

    1994-01-01

    Variations in atmospheric angular momentum (AAM) are examined in a three-year simulation of the large-scale atmosphere with perpetual January forcing. The simulation is performed with a version of the University of California at Los Angeles (UCLA) general circulation model that contains no tropical Madden-Julian Oscillation (MJO). In addition, the results of three shorter experiments with no topography are analyzed. The three-year standard topography run contains no significant intraseasonal AAM periodicity in the tropics, consistent with the lack of the MJO, but produces a robust, 42-day AAM oscillation in the Northern Hemisphere (NH) extratropics. The model tropics undergoes a barotropic, zonally symmetric oscillation, driven by an exchange of mass with the NH extratropics. No intraseasonal periodicity is found in the average tropical latent heating field, indicating that the model oscillation is dynamically rather than thermodynamically driven. The no-mountain runs fail to produce an intraseasonal AAM oscillation, consistent with a topographic origin for the NH extratropical oscillation in the standard model. The spatial patterns of the oscillation in the 500-mb height field, and the relationship of the extratropical oscillation to intraseasonal variations in the tropics, will be discussed in Part 2 of this study.

  18. The Tropical Subseasonal Variability Simulated in the NASA GISS General Circulation Model

    NASA Technical Reports Server (NTRS)

    Kim, Daehyun; Sobel, Adam H.; DelGenio, Anthony D.; Chen, Yonghua; Camargo, Suzana J.; Yao, Mao-Sung; Kelley, Maxwell; Nazarenko, Larissa

    2012-01-01

    The tropical subseasonal variability simulated by the Goddard Institute for Space Studies general circulation model, Model E2, is examined. Several versions of Model E2 were developed with changes to the convective parameterization in order to improve the simulation of the Madden-Julian oscillation (MJO). When the convective scheme is modified to have a greater fractional entrainment rate, Model E2 is able to simulate MJO-like disturbances with proper spatial and temporal scales. Increasing the rate of rain reevaporation has additional positive impacts on the simulated MJO. The improvement in MJO simulation comes at the cost of increased biases in the mean state, consistent in structure and amplitude with those found in other GCMs when tuned to have a stronger MJO. By reinitializing a relatively poor-MJO version with restart files from a relatively better-MJO version, a series of 30-day integrations is constructed to examine the impacts of the parameterization changes on the organization of tropical convection. The poor-MJO version with smaller entrainment rate has a tendency to allow convection to be activated over a broader area and to reduce the contrast between dry and wet regimes so that tropical convection becomes less organized. Besides the MJO, the number of tropical-cyclone-like vortices simulated by the model is also affected by changes in the convection scheme. The model simulates a smaller number of such storms globally with a larger entrainment rate, while the number increases significantly with a greater rain reevaporation rate.

  19. A System of Conservative Regridding for Ice-Atmosphere Coupling in a General Circulation Model (GCM)

    NASA Technical Reports Server (NTRS)

    Fischer, R.; Nowicki, S.; Kelley, M.; Schmidt, G. A.

    2014-01-01

    The method of elevation classes, in which the ice surface model is run at multiple elevations within each grid cell, has proven to be a useful way for a low-resolution atmosphere inside a general circulation model (GCM) to produce high-resolution downscaled surface mass balance fields for use in one-way studies coupling atmospheres and ice flow models. Past uses of elevation classes have failed to conserve mass and energy because the transformation used to regrid to the atmosphere was inconsistent with the transformation used to downscale to the ice model. This would cause problems for two-way coupling. A strategy that resolves this conservation issue has been designed and is presented here. The approach identifies three grids between which data must be regridded and five transformations between those grids required by a typical coupled atmosphere-ice flow model. This paper develops a theoretical framework for the problem and shows how each of these transformations may be achieved in a consistent, conservative manner. These transformations are implemented in Glint2, a library used to couple atmosphere models with ice models. Source code and documentation are available for download. Confounding real-world issues are discussed, including the use of projections for ice modeling, how to handle dynamically changing ice geometry, and modifications required for finite element ice models.

  20. General mechanism and dynamics of the solar wind interaction with lunar magnetic anomalies from 3-D particle-in-cell simulations

    NASA Astrophysics Data System (ADS)

    Deca, Jan; Divin, Andrey; Lembège, Bertrand; Horányi, Mihály; Markidis, Stefano; Lapenta, Giovanni

    2015-08-01

    We present a general model of the solar wind interaction with a dipolar lunar crustal magnetic anomaly (LMA) using three-dimensional full-kinetic and electromagnetic simulations. We confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface, forming a so-called "minimagnetosphere," as suggested by spacecraft observations and theory. We show that the LMA configuration is driven by electron motion because its scale size is small with respect to the gyroradius of the solar wind ions. We identify a population of back-streaming ions, the deflection of magnetized electrons via the E × B drift motion, and the subsequent formation of a halo region of elevated density around the dipole source. Finally, it is shown that the presence and efficiency of the processes are heavily impacted by the upstream plasma conditions and, on their turn, influence the overall structure and evolution of the LMA system. Understanding the detailed physics of the solar wind interaction with LMAs, including magnetic shielding, particle dynamics and surface charging is vital to evaluate its implications for lunar exploration.

  1. A generalized crystal-cutting method for modeling arbitrarily oriented crystals in 3D periodic simulation cells with applications to crystal-crystal interfaces

    NASA Astrophysics Data System (ADS)

    Kroonblawd, Matthew P.; Mathew, Nithin; Jiang, Shan; Sewell, Thomas D.

    2016-10-01

    A Generalized Crystal-Cutting Method (GCCM) is developed that automates construction of three-dimensionally periodic simulation cells containing arbitrarily oriented single crystals and thin films, two-dimensionally (2D) infinite crystal-crystal homophase and heterophase interfaces, and nanostructures with intrinsic N-fold interfaces. The GCCM is based on a simple mathematical formalism that facilitates easy definition of constraints on cut crystal geometries. The method preserves the translational symmetry of all Bravais lattices and thus can be applied to any crystal described by such a lattice including complicated, low-symmetry molecular crystals. Implementations are presented with carefully articulated combinations of loop searches and constraints that drastically reduce computational complexity compared to simple loop searches. Orthorhombic representations of monoclinic and triclinic crystals found using the GCCM overcome some limitations in standard distributions of popular molecular dynamics software packages. Stability of grain boundaries in β-HMX was investigated using molecular dynamics and molecular statics simulations with 2D infinite crystal-crystal homophase interfaces created using the GCCM. The order of stabilities for the four grain boundaries studied is predicted to correlate with the relative prominence of particular crystal faces in lab-grown β-HMX crystals. We demonstrate how nanostructures can be constructed through simple constraints applied in the GCCM framework. Example GCCM constructions are shown that are relevant to some current problems in materials science, including shock sensitivity of explosives, layered electronic devices, and pharmaceuticals.

  2. Uncertainties in the projection of species distributions related to general circulation models

    PubMed Central

    Goberville, Eric; Beaugrand, Grégory; Hautekèete, Nina-Coralie; Piquot, Yves; Luczak, Christophe

    2015-01-01

    Ecological Niche Models (ENMs) are increasingly used by ecologists to project species potential future distribution. However, the application of such models may be challenging, and some caveats have already been identified. While studies have generally shown that projections may be sensitive to the ENM applied or the emission scenario, to name just a few, the sensitivity of ENM-based scenarios to General Circulation Models (GCMs) has been often underappreciated. Here, using a multi-GCM and multi-emission scenario approach, we evaluated the variability in projected distributions under future climate conditions. We modeled the ecological realized niche (sensu Hutchinson) and predicted the baseline distribution of species with contrasting spatial patterns and representative of two major functional groups of European trees: the dwarf birch and the sweet chestnut. Their future distributions were then projected onto future climatic conditions derived from seven GCMs and four emissions scenarios using the new Representative Concentration Pathways (RCPs) developed for the Intergovernmental Panel on Climate Change (IPCC) AR5 report. Uncertainties arising from GCMs and those resulting from emissions scenarios were quantified and compared. Our study reveals that scenarios of future species distribution exhibit broad differences, depending not only on emissions scenarios but also on GCMs. We found that the between-GCM variability was greater than the between-RCP variability for the next decades and both types of variability reached a similar level at the end of this century. Our result highlights that a combined multi-GCM and multi-RCP approach is needed to better consider potential trajectories and uncertainties in future species distributions. In all cases, between-GCM variability increases with the level of warming, and if nothing is done to alleviate global warming, future species spatial distribution may become more and more difficult to anticipate. When future species

  3. Snow cover and snow mass intercomparisons of general circulation models and remotely sensed datasets

    SciTech Connect

    Foster, J.; Liston, G.; Koster, R.

    1996-02-01

    Confirmation of the ability of general circulation models (GCMs) to accurately represent snow cover and snow mass distributions is vital for climate studies. There must be a high degree of confidence that what is being predicted by the models is reliable. In this study, snow output from seven GCMs and passive-microwave snow data derived from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) are intercompared. National Oceanic and Atmospheric Administration satellite data are used as the standard of reference for snow extent observations and the U.S. Air Force snow depth climatology is used as the standard for snow mass. The reliability of the SMMR snow data needs to be verified, as well. Data for both North America and Eurasia are examined in an effort to assess the magnitude of spatial and temporal variations that exist between the standards of reference, the models, and the passive microwave data. Results indicate that both the models and SMMR represent seasonal and year-to-year snow distributions fairly well. The passive microwave data and several of the models, however, consistently underestimate snow mass, but other models overestimate the mass of snow on the ground. The models do a better job simulating winter and summer snow conditions than in the transition months. In general, the underestimation by SMR is caused by absorption of microwave energy by vegetation. For the GCMs, differences between observed snow conditions can be ascribed to inaccuracies in simulating surface air temperatures and precipitation fields, especially during the spring and fall. 34 refs., 18 figs.

  4. Uncertainties in the projection of species distributions related to general circulation models.

    PubMed

    Goberville, Eric; Beaugrand, Grégory; Hautekèete, Nina-Coralie; Piquot, Yves; Luczak, Christophe

    2015-03-01

    Ecological Niche Models (ENMs) are increasingly used by ecologists to project species potential future distribution. However, the application of such models may be challenging, and some caveats have already been identified. While studies have generally shown that projections may be sensitive to the ENM applied or the emission scenario, to name just a few, the sensitivity of ENM-based scenarios to General Circulation Models (GCMs) has been often underappreciated. Here, using a multi-GCM and multi-emission scenario approach, we evaluated the variability in projected distributions under future climate conditions. We modeled the ecological realized niche (sensu Hutchinson) and predicted the baseline distribution of species with contrasting spatial patterns and representative of two major functional groups of European trees: the dwarf birch and the sweet chestnut. Their future distributions were then projected onto future climatic conditions derived from seven GCMs and four emissions scenarios using the new Representative Concentration Pathways (RCPs) developed for the Intergovernmental Panel on Climate Change (IPCC) AR5 report. Uncertainties arising from GCMs and those resulting from emissions scenarios were quantified and compared. Our study reveals that scenarios of future species distribution exhibit broad differences, depending not only on emissions scenarios but also on GCMs. We found that the between-GCM variability was greater than the between-RCP variability for the next decades and both types of variability reached a similar level at the end of this century. Our result highlights that a combined multi-GCM and multi-RCP approach is needed to better consider potential trajectories and uncertainties in future species distributions. In all cases, between-GCM variability increases with the level of warming, and if nothing is done to alleviate global warming, future species spatial distribution may become more and more difficult to anticipate. When future species

  5. Estimates of Bottom Flows and Bottom Boundary Layer Dissipation of the Oceanic General Circulation from Global High-Resolution Models

    DTIC Science & Technology

    2009-02-27

    Penduff et , • , ». r HI J m 1 mno m • , -„„,, . . * . , general circulation [e.g., Munk and Wunsch, 1998...model variables and all grid points in the vertical and horizontal directions, because of the unfeasibly large stor- age and analysis computers that

  6. Understanding Titan's Methane Cycle Using the TitanWRF General Circulation Model

    NASA Astrophysics Data System (ADS)

    Newman, C. E.; Richardson, M. I.; Lian, Y.; Lee, C.

    2013-12-01

    Titan has been inferred to have an active methane hydrological cycle, with convective clouds observed in the troposphere, high latitude lakes thought to be composed of methane and ethane, and evidence of past and recent rainfall at the surface. While theory and simple analytical modeling provide valuable insights, and are extremely useful in forming hypotheses, most phenomena linked to the atmospheric circulation require detailed modeling to be fully understood, as non-linear interactions and feedbacks can produce complex and/or unexpected results. The most rigorous way to examine possible mechanisms and explore hypotheses related to Titan's methane cycle is therefore by modeling Titan's entire atmosphere-surface system using a three-dimensional Titan general circulation model (GCM). Observations of diverse phenomena can be used to constrain many aspects of the GCM, from parameter values to the physical processes we should include. We can then use the GCM to provide insight into the mechanisms behind such phenomena, and ultimately to provide predictive capabilities. TitanWRF is the Titan version of the planetWRF GCM, and is described in detail in Newman et al., Icarus v. 213 (2011). It produces realistically large stratospheric superrotation, and currently includes a simple methane cycle: condensation occurs when methane exceeds a prescribed relative humidity Rc at a model grid point; this methane falls immediately to the surface as precipitation, unless a grid point with humidity less than Rc is encountered on the way down; methane evaporation is also parameterized at the surface based on wind stress and sub-saturation of the near-surface layer; and the surface methane abundance (affected by evaporation and precipitation) is tracked throughout. The scheme also includes surface and atmospheric latent heating effects. TitanWRF simulations are begun with a finite initial surface methane abundance, and evolve over time to produce a surface methane distribution with

  7. Pathways for Learning from 3D Technology

    PubMed Central

    Carrier, L. Mark; Rab, Saira S.; Rosen, Larry D.; Vasquez, Ludivina; Cheever, Nancy A.

    2016-01-01

    The purpose of this study was to find out if 3D stereoscopic presentation of information in a movie format changes a viewer's experience of the movie content. Four possible pathways from 3D presentation to memory and learning were considered: a direct connection based on cognitive neuroscience research; a connection through "immersion" in that 3D presentations could provide additional sensorial cues (e.g., depth cues) that lead to a higher sense of being surrounded by the stimulus; a connection through general interest such that 3D presentation increases a viewer’s interest that leads to greater attention paid to the stimulus (e.g., "involvement"); and a connection through discomfort, with the 3D goggles causing discomfort that interferes with involvement and thus with memory. The memories of 396 participants who viewed two-dimensional (2D) or 3D movies at movie theaters in Southern California were tested. Within three days of viewing a movie, participants filled out an online anonymous questionnaire that queried them about their movie content memories, subjective movie-going experiences (including emotional reactions and "presence") and demographic backgrounds. The responses to the questionnaire were subjected to path analyses in which several different links between 3D presentation to memory (and other variables) were explored. The results showed there were no effects of 3D presentation, either directly or indirectly, upon memory. However, the largest effects of 3D presentation were on emotions and immersion, with 3D presentation leading to reduced positive emotions, increased negative emotions and lowered immersion, compared to 2D presentations. PMID:28078331

  8. Outflow Channels and Martian Climate: General Circulation Model (GCM) Simulations with Emplaced Water and Cloud Physics

    NASA Astrophysics Data System (ADS)

    Santiago, D.; Colaprete, A.; Haberle, R.; Asphaug, E.; Sloan, L.

    2005-12-01

    One of the most intriguing signatures of surface water on Mars is large outflow channels believed to have been carved out by gigantic flood events in the late Noachian or Hesperian. We use the NASA Ames Mars General Circulation Model (MGCM) to study how abrupt eruption of water onto the Martian surface might have affected the early climate of Mars, and to calculate where the water ultimately went as part of a transient hydrologic cycle. Our model includes the emplacement of large amounts of water onto the surface of a cold, dry Mars in the vicinity of Ares Valles, with current day orbital configurations. Specifically, 106 km3 of water was released at a rate of 0.1 km3/s at end of Northern Hemisphere summer. We have begun modeling with the MGCM with outflow water and cloud physics. The current cloud physics include cloud particle nucleation and growth, with radiative effects added at a later date. These results are being compared with a control case with no outflow in the model, and a case with water, but without clouds. In all cases we are examining the radiative effects of water vapor, albedo effects of water ice, and latent heat effects for this large influx of water. Preliminary results show differences between these three cases, but the factors that are causing these differences have not yet been determined. These results will be interesting to compare with studies that suggest significant, but possibly localized or regional, precipitation in the Hesperian, as opposed to the more widely recognized precipitation during the Noachian. Current analyses and longer model runs will allow us to calculate the specific effects of outflow water on past Martian climate, as well as where the water might have ended up.

  9. Outflow Channels and Martian Climate: General Circulation Model (GCM) Simulations with Emplaced Water

    NASA Astrophysics Data System (ADS)

    Santiago, D.; Colaprete, A.; Haberle, R.; Asphaug, E.; Sloan, L.

    2005-08-01

    The existence of past surface water on Mars has been inferred on the basis of geomorphologic interpretation of spacecraft images. Among the most intriguing signatures of surface water are large outflow channels believed to have been carved out by gigantic flood events in the late Noachian or Hesperian. We use the NASA Ames Mars General Circulation Model (MGCM) to study how abrupt eruption of water onto the Martian surface might have affected climate, and to consider where the water ultimately went. Our initial model begins by emplacing large amounts of water onto the surface of Mars in the vicinity of Ares Valley, for current day orbital configurations. Specifically, 10\\^6 km\\^3 of water was released at a rate of 0.1 km\\^3/s at end of Northern summer. The MGCM was run for 10 years; a control version, without water, was run the same length of time, in order to assess the climatic impact from the radiative and thermal effects of the released water. Model modifications for the results that will be presented include (1) a customized sublimation scheme, (2) latent heat effects of water transitions, (3) radiative effects of water vapor, (4) albedo effects, and (5) clouds. Preliminary results indicate slight surface temperature increases due to latent heating is areas of water deposition, and cooling in the outflow formation area. Results also suggest that water vapor is distributed throughout the atmosphere. Results for these and other atmospheric variables, as well as water tracer distribution, will be presented. We acknowledge the University Aligned Research Center and the Mars Fundamental Research Program for their funding contributions.

  10. Global Radiative Forcing of Coupled Tropospheric Ozone and Aerosols in a Unified General Circulation Model

    NASA Technical Reports Server (NTRS)

    Liao, Hong; Seinfeld, John H.; Adams, Peter J.; Mickley, Loretta J.

    2008-01-01

    Global simulations of sea salt and mineral dust aerosols are integrated into a previously developed unified general circulation model (GCM), the Goddard Institute for Space Studies (GISS) GCM II', that simulates coupled tropospheric ozone-NOx-hydrocarbon chemistry and sulfate, nitrate, ammonium, black carbon, primary organic carbon, and secondary organic carbon aerosols. The fully coupled gas-aerosol unified GCM allows one to evaluate the extent to which global burdens, radiative forcing, and eventually climate feedbacks of ozone and aerosols are influenced by gas-aerosol chemical interactions. Estimated present-day global burdens of sea salt and mineral dust are 6.93 and 18.1 Tg with lifetimes of 0.4 and 3.9 days, respectively. The GCM is applied to estimate current top of atmosphere (TOA) and surface radiative forcing by tropospheric ozone and all natural and anthropogenic aerosol components. The global annual mean value of the radiative forcing by tropospheric ozone is estimated to be +0.53 W m(sup -2) at TOA and +0.07 W m(sup -2) at the Earth's surface. Global, annual average TOA and surface radiative forcing by all aerosols are estimated as -0.72 and -4.04 W m(sup -2), respectively. While the predicted highest aerosol cooling and heating at TOA are -10 and +12 W m(sup -2) respectively, surface forcing can reach values as high as -30 W m(sup -2), mainly caused by the absorption by black carbon, mineral dust, and OC. We also estimate the effects of chemistry-aerosol coupling on forcing estimates based on currently available understanding of heterogeneous reactions on aerosols. Through altering the burdens of sulfate, nitrate, and ozone, heterogeneous reactions are predicted to change the global mean TOA forcing of aerosols by 17% and influence global mean TOA forcing of tropospheric ozone by 15%.

  11. Effective diffusivity in the middle atmosphere based on general circulation model winds

    NASA Astrophysics Data System (ADS)

    Kostrykin, S. V.; Schmitz, G.

    2006-01-01

    The mixing of a passive tracer in the stratosphere and lower mesosphere is studied on the basis of the effective diffusivity, which is obtained in the framework of the tracer-based coordinate system. This characteristic is proportional to the average diffusion flux over Lagrangian contours and inversely proportional to the mean tracer gradient. The tracer distribution used in the calculation of the effective diffusivity is obtained after integration of the advection-diffusion equation using general circulation model winds and a new numerical advection scheme with small numerical diffusivity. Using some theoretical and experimental arguments, it is shown that the interpretation of the seasonal variability of the effective diffusivity field cannot be done on the basis of the momentary wind field alone, but some flow history should be taken into account. The climatology of the effective diffusivity for different months is presented up to the lower mesosphere and compared with previous studies. In the stratosphere some new features of the effective diffusivity distribution are obtained. For example, there is a local maximum of the effective diffusivity at midlatitudes of the Northern Hemisphere of the summer middle stratosphere. The effective diffusivity fields in the lower mesosphere show a strong increase of the mean effective diffusivity from the upper stratosphere to the lower mesosphere and the existence of a complex latitudinal structure of the effective diffusivity at mesospheric heights. In the lower mesosphere there is a marked interannual variability during the Southern Hemisphere easterly wind development. A possible explanation for the obtained structure is discussed on the basis of in situ Rossby wave generation and Rossby-wave-breaking effects.

  12. Modeling of subaqueous melting in Petermann Fjord, Northwestern Greenland using an ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Cai, C.; Rignot, E. J.; Xu, Y.; An, L.; Tinto, K. J.; van den Broeke, M. R.

    2014-12-01

    Basal melting of the floating tongue of Petermann Glacier, in northwestern Greenland is by far the largest process of mass ablation. Melting of the floating tongue is controlled by the buoyancy of the melt water plume, the pressure-dependence of the melting point of sea ice, and the mixing of warm subsurface water with fresh buoyant subglacial discharge. In prior simulations of this melting process, the role of subglacial discharge has been neglected because in similar configurations (floating ice shelves) in the Antarctic, surface runoff is negligible; this is however not true in Greenland. Here, we use the Mass Institute of Technology general circulation model (MITgcm) at a high spatial resolution (10 m x 10 m) to simulate the melting process of the ice shelf in 2-D. The model is constrained by ice shelf bathymetry and ice thickness (refined model in the immediate vicinity of the grounding line) from NASA Operation IceBridge (2011), ocean temperature/salinity data from Johnson et al. (2011), ocean tide height and current from the Arctic Ocean Tidal Inverse Model (AOTIM-5) by Padman and Erofeeva (2004) and subglacial discharge at the grounding line calculated by the hydrostatic potential of the ice from estimated products of the Regional Atmospheric Climate Model (RACMO) of Royal Netherlands Meteorological Institute (KNMI). We compare the results obtained in winter (no runoff) with summer, and the sensitivity of the results to thermal forcing from the ocean, and to the variation of tide height and current, and to the magnitude of subglacial runoff. We conclude on the impact of the ocean and surface melting on the melting regime of the floating ice tongue of Petermann. The basal melt rate increases ~20% with summer surface runoff. This work is performed under a contract with NASA Cryosphere Program.

  13. Atmospheric radiation measurement: A program for improving radiative forcing and feedback in general circulation models

    SciTech Connect

    Patrinos, A.A. ); Renne, D.S.; Stokes, G.M. ); Ellingson, R.G. )

    1991-01-01

    The Atmospheric Radiation Measurement (ARM) Program is a key element of the Department of Energy's (DOE's) global change research strategy. ARM represents a long-term commitment to conduct comprehensive studies of the spectral atmospheric radiative energy balance profile for a wide range of cloud conditions and surface types, and to develop the knowledge necessary to improve parameterizations of radiative processes under various cloud regimes for use in general circulation models (GCMs) and related models. The importance of the ARM program is a apparent from the results of model assessments of the impact on global climate change. Recent studies suggest that radiatively active trace gas emissions caused by human activity can lead to a global warming of 1.5 to 4.5 degrees Celsius and to important changes in water availability during the next century (Cess, et al. 1989). These broad-scale changes can be even more significant at regional levels, where large shifts in temperature and precipitation patterns are shown to occur. However, these analyses also indicate that considerable uncertainty exists in these estimates, with the manner in which cloud radiative processes are parameterized among the most significant uncertainty. Thus, although the findings have significant policy implications in assessment of global and regional climate change, their uncertainties greatly influence the policy debate. ARM's highly focused observational and analytical research is intended to accelerate improvements and reduce key uncertainties associated with the way in which GCMs treat cloud cover and cloud characteristics and the resulting radiative forcing. This paper summarizes the scientific context for ARM, ARM's experimental approach, and recent activities within the ARM program.

  14. Atmospheric radiation measurement: A program for improving radiative forcing and feedback in general circulation models

    SciTech Connect

    Patrinos, A.A.; Renne, D.S.; Stokes, G.M.; Ellingson, R.G.

    1991-01-01

    The Atmospheric Radiation Measurement (ARM) Program is a key element of the Department of Energy`s (DOE`s) global change research strategy. ARM represents a long-term commitment to conduct comprehensive studies of the spectral atmospheric radiative energy balance profile for a wide range of cloud conditions and surface types, and to develop the knowledge necessary to improve parameterizations of radiative processes under various cloud regimes for use in general circulation models (GCMs) and related models. The importance of the ARM program is a apparent from the results of model assessments of the impact on global climate change. Recent studies suggest that radiatively active trace gas emissions caused by human activity can lead to a global warming of 1.5 to 4.5 degrees Celsius and to important changes in water availability during the next century (Cess, et al. 1989). These broad-scale changes can be even more significant at regional levels, where large shifts in temperature and precipitation patterns are shown to occur. However, these analyses also indicate that considerable uncertainty exists in these estimates, with the manner in which cloud radiative processes are parameterized among the most significant uncertainty. Thus, although the findings have significant policy implications in assessment of global and regional climate change, their uncertainties greatly influence the policy debate. ARM`s highly focused observational and analytical research is intended to accelerate improvements and reduce key uncertainties associated with the way in which GCMs treat cloud cover and cloud characteristics and the resulting radiative forcing. This paper summarizes the scientific context for ARM, ARM`s experimental approach, and recent activities within the ARM program.

  15. The sulfur cycle at high-southern latitudes in the LMD-ZT General Circulation Model

    NASA Astrophysics Data System (ADS)

    Cosme, E.; Genthon, C.; Martinerie, P.; Boucher, O.; Pham, M.

    2002-12-01

    This modeling study was motivated by the recent publication of year-round records of dimethylsulfide (DMS) and dimethylsulfoxide (DMSO) in Antarctica, completing the available series of sulfate and methanesulfonic acid (MSA). Sulfur chemistry has been incorporated in the Laboratoire de Météorologie Dynamique-Zoom Tracers (LMD-ZT) Atmospheric General Circulation Model (AGCM), with high-resolution and improved physics at high-southern latitudes. The model predicts the concentration of six major sulfur species through emissions, transport, wet and dry deposition, and chemistry in both gas and aqueous phases. Model results are broadly realistic when compared with measurements in air and snow or ice, as well as to results of other modeling studies, at high- and middle-southern latitudes. Atmospheric MSA concentrations are underestimated and DMSO concentrations are overestimated in summer, reflecting the lack of a DMSO heterogeneous sink leading to MSA. Experiments with various recently published estimates of the rate of this sink are reported. Although not corrected in this work, other defects are identified and discussed: DMS concentrations are underestimated in winter, MSA and non-sea-salt (nss) sulfate concentrations may be underestimated at the South Pole, the deposition scheme used in the model may not be adapted to polar regions, and the model does not adequately reproduces interannual variability. Oceanic DMS sources have a major contribution to the variability of sulfur in these regions. The model results suggest that in a large part of central Antarctica ground-level atmospheric DMS concentrations are larger in winter than in summer. At high-southern latitudes, high loads of DMS and DMSO are found and the main chemical sink of sulfur dioxide (SO2) is aqueous oxidation by ozone (O3), whereas oxidation by hydrogen peroxide (H2O2) dominates at the global scale. A comprehensive modeled sulfur budget of Antarctica is provided.

  16. Development of the GEOS-5 Atmospheric General Circulation Model: Evolution from MERRA to MERRA2.

    NASA Technical Reports Server (NTRS)

    Molod, Andrea; Takacs, Lawrence; Suarez, Max; Bacmeister, Julio

    2014-01-01

    The Modern-Era Retrospective Analysis for Research and Applications-2 (MERRA2) version of the GEOS-5 (Goddard Earth Observing System Model - 5) Atmospheric General Circulation Model (AGCM) is currently in use in the NASA Global Modeling and Assimilation Office (GMAO) at a wide range of resolutions for a variety of applications. Details of the changes in parameterizations subsequent to the version in the original MERRA reanalysis are presented here. Results of a series of atmosphere-only sensitivity studies are shown to demonstrate changes in simulated climate associated with specific changes in physical parameterizations, and the impact of the newly implemented resolution-aware behavior on simulations at different resolutions is demonstrated. The GEOS-5 AGCM presented here is the model used as part of the GMAO's MERRA2 reanalysis, the global mesoscale "nature run", the real-time numerical weather prediction system, and for atmosphere-only, coupled ocean-atmosphere and coupled atmosphere-chemistry simulations. The seasonal mean climate of the MERRA2 version of the GEOS-5 AGCM represents a substantial improvement over the simulated climate of the MERRA version at all resolutions and for all applications. Fundamental improvements in simulated climate are associated with the increased re-evaporation of frozen precipitation and cloud condensate, resulting in a wetter atmosphere. Improvements in simulated climate are also shown to be attributable to changes in the background gravity wave drag, and to upgrades in the relationship between the ocean surface stress and the ocean roughness. The series of "resolution aware" parameters related to the moist physics were shown to result in improvements at higher resolutions, and result in AGCM simulations that exhibit seamless behavior across different resolutions and applications.

  17. How Do Biases in General Circulation Models Affect Projections of Aridity and Drought?

    NASA Astrophysics Data System (ADS)

    Ficklin, D. L.; Abatzoglou, J. T.; Robeson, S. M.; Dufficy, A. L.

    2015-12-01

    Unless corrected, biases in General Circulation Models (GCMs) can affect hydroclimatological applications and projections. Compared to a raw GCM ensemble (direct GCM output), bias-corrected GCM inputs correct for systematic errors and can produce high-resolution projections that are useful for impact analyses. By examining the difference between raw and bias-corrected GCMs for the continental United States, this work highlights how GCM biases can affect projections of aridity (defined as precipitation (P)/potential evapotranspiration (PET)) and drought (using the Palmer Drought Severity Index (PDSI)). At the annual time scale for spatial averages over the continental United States, the raw GCM ensemble median has a historical positive precipitation bias (+24%) and negative PET bias (-7%) compared to the bias-corrected output. While both GCM ensembles (raw and bias-corrected) result in drier conditions in the future, the bias-corrected GCMs produce enhanced aridity (number of months with PET>P) in the late 21st century (2070-2099) compared to the historical climate (1950-1979). For the western United States, the bias-corrected GCM ensemble estimates much less humid and sub-humid conditions (based on P/PET categorical values) than the raw GCM ensemble. However, using June, July, and August PDSI, the bias-corrected GCM ensemble projects less acute decreases for the southwest United States compared to the raw GCM ensemble (1 to 2 PDSI units higher) as a result of larger decreases in projected precipitation in the raw GCM ensemble. A number of examples and ecological implications of this work for the western United States will be presented.

  18. Distribution and budget of O3 in the troposphere calculated with a chemistry general circulation model

    NASA Astrophysics Data System (ADS)

    Roelofs, Geert-Jan; Lelieveld, Jos

    1995-10-01

    We present results of global tropospheric chemistry simulations with the coupled chemistry/atmospheric general circulation model ECHAM. Ultimately, the model will be used to study climate changes induced by anthropogenic influences on the chemistry of the atmosphere; meteorological parameters that are important for the chemistry, such as temperature, humidity, air motions, cloud and rain characteristics, and mixing processes are calculated on-line. The chemical part of the model describes background tropospheric CH4-CO-NOx-HOx photochemistry. Emissions of NO and CO, surface concentrations of CH4, and stratospheric concentrations of O3 and NOy are prescribed as boundary conditions. Calculations of the tropospheric O3 budget indicate that seasonal variabilities of the photochemical production and of injection from the stratosphere are represented realistically, although some aspects of the model still need improvement. Comparisons of calculated O3 surface concentrations and O3 profiles with available measurements show that the model reproduces O3 distributions in remote tropical and midlatitudinal sites. Also, the model matches typical profiles connected with deep convection in the Intertropical Convergence Zone (ITCZ). However, the model tends to underestimate O3 concentrations at the poles and in relatively polluted regions. These underestimates are caused by the poor representation of tropopause foldings in midlatitudes, which form a significant source of tropospheric O3 from the stratosphere, too weak transport to the poles, and the neglect of higher hydrocarbon chemistry. Also, mixing of polluted continental boundary layer air into the free troposphere may be underestimated. We discuss how these model deficiencies will be improved in the future.

  19. Tropospheric ozone simulation with a chemistry-general circulation model: Influence of higher hydrocarbon chemistry

    NASA Astrophysics Data System (ADS)

    Roelofs, Geert-Jan; Lelieveld, Jos

    2000-09-01

    We present an improved version of the global chemistry-general circulation model of Roelofs and Lelieveld [1997]. The major model improvement is the representation of higher hydrocarbon chemistry, implemented by means of the Carbon Bond Mechanism 4 (CBM-4). Simulated tropospheric ozone concentrations at remote locations, which agreed well with observations in the previous model version, are not affected much by the chemistry of higher hydrocarbons. However, ozone formation in the polluted boundary layer is significantly enhanced, resulting in a more realistic simulation of surface ozone in regions such as North America, Europe, and Southeast Asia. Our model simulates a net global tropospheric ozone production of 73 Tg yr-1 when higher hydrocarbon chemistry is considered, and -36 Tg yr-1 without higher hydrocarbon chemistry. The simulated seasonality of surface CO agrees well with observations. However, the southern hemispheric maximum for O3 and CO associated with biomass burning emissions is delayed by 1 month compared to the observations, which demonstrates the need for a better representation of biomass burning emissions. Simulated peroxyacetyl nitrate (PAN) concentrations agree well with observed values, although the variability is underestimated. OH decreases strongly in the continental boundary layer due to its reaction with higher hydrocarbons. However, this is almost compensated by an increase of OH over oceans in the lower half of the troposphere. Consideration of higher hydrocarbon chemistry decreases the global annual tropospheric OH concentration by about 8% compared to a background tropospheric chemistry scheme. Further, the radiative forcing by anthropogenically increased tropospheric ozone on the northern hemisphere increases, especially in July. The forcing also increases on the southern hemisphere where biomass burning emissions produce tropospheric ozone, except between December and June, that is, outside the biomass burning season, when ozone

  20. Evaluation of a Mineral Dust Simulation in the Atmospheric-Chemistry General Circulation Model-EMAC

    NASA Astrophysics Data System (ADS)

    Abdel Kader, M.; Astitha, M.; Lelieveld, J.

    2012-04-01

    This study presents an evaluation of the atmospheric mineral dust cycle in the Atmospheric Chemistry General Circulation Model (AC-GCM) using new developed dust emissions scheme. The dust cycle, as an integral part of the Earth System, plays an important role in the Earth's energy balance by both direct and indirect ways. As an aerosol, it significantly impacts the absorption and scattering of radiation in the atmosphere and can modify the optical properties of clouds and snow/ice surfaces. In addition, dust contributes to a range of physical, chemical and bio-geological processes that interact with the cycles of carbon and water. While our knowledge of the dust cycle, its impacts and interactions with the other global-scale bio-geochemical cycles has greatly advanced in the last decades, large uncertainties and knowledge gaps still exist. Improving the dust simulation in global models is essential to minimize the uncertainties in the model results related to dust. In this study, the results are based on the ECHAM5 Modular Earth Submodel System (MESSy) AC-GCM simulations using T106L31 spectral resolution (about 120km ) with 31 vertical levels. The GMXe aerosol submodel is used to simulate the phase changes of the dust particles between soluble and insoluble modes. Dust emission, transport and deposition (wet and dry) are calculated on-line along with the meteorological parameters in every model time step. The preliminary evaluation of the dust concentration and deposition are presented based on ground observations from various campaigns as well as the evaluation of the optical properties of dust using AERONET and satellite (MODIS and MISR) observations. Preliminarily results show good agreement with observations for dust deposition and optical properties. In addition, the global dust emissions, load, deposition and lifetime is in good agreement with the published results. Also, the uncertainties in the dust cycle that contribute to the overall model performance

  1. Global environmental effects of impact-generated aerosols: Results from a general circulation model

    NASA Technical Reports Server (NTRS)

    Covey, C.; Ghan, S. J.; Weissman, Paul R.

    1988-01-01

    Cooling and darkening at Earth's surface are expected to result from the interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet, according to the one-dimensional radioactive-convective atmospheric model (RCM) of Pollack et al. An analogous three-dimensional general circulation model (GCM) simulation obtains the same basic result as the RCM but there are important differences in detail. In the GCM simulation the heat capacity of the oceans, not included in the RCM, substantially mitigates land surface cooling. On the other hand, the GCM's low heat capacity surface allows surface temperatures to drop much more rapidly than reported by Pollack et al. These two differences between RCM and GCM simulations were noted previously in studies of nuclear winter; GCM results for comet/asteroid winter, however, are much more severe than for nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on Earth. In the simulation the global average of land surface temperature drops to the freezing point in just 4.5 days, one-tenth the time required in the Pollack et al. simulation. In addition to the standard case of Pollack et al., which represents the collision of a 10-km diameter asteroid with Earth, additional scenarios are considered ranging from the statistically more frequent impacts of smaller asteroids to the collision of Halley's comet with Earth. In the latter case the kinetic energy of impact is extremely large due to the head-on collision resulting from Halley's retrograde orbit.

  2. Sensitivity of a general circulation model to global changes in leaf area index

    NASA Astrophysics Data System (ADS)

    Chase, Thomas N.; Pielke, Roger A.; Kittel, Timothy G. F.; Nemani, Ramakrishna; Running, Steven W.

    1996-03-01

    Methods have recently become available for estimating the amount of leaf area at the surface of the Earth using satellite data. Also available are modeled estimates of what global leaf area patterns would look like should the vegetation be in equilibrium with current local climatic and soil conditions. The differences between the actual vegetation distribution and the potential vegetation distribution may reflect the impact of human activity on the Earth's surface. To examine model sensitivity to changes in leaf area index (LAI), global distributions of maximum LAI were used as surface boundary conditions in the National Center for Atmospheric Research community climate model (NCAR CCM2) coupled with the biosphere atmosphere transfer scheme (BATS). Results from 10-year ensemble averages for the months of January and July indicate that the largest effects of the decreased LAI in the actual LAI simulation occur in the northern hemisphere winter at high latitudes despite the fact that direct LAI forcing is negligible in these regions at this time of year. This is possibly a result of LAI forcing in the tropics which has long-ranging effects in the winter of both hemispheres. An assessment of the Asian monsoon region for the month of July shows decreased latent heat flux from the surface, increased surface temperature, and decreased precipitation with the actual LAI distribution. While the statistical significance of the results has not been unambiguously established in these simulations, we suspect that an effect on modeled general circulation dynamics has occurred due to changes of maximum LAI suggesting that further attention needs to be paid to the accurate designation of vegetation parameters. The incorporation of concomitant changes in albedo, vegetation fractional coverage, and roughness length is suggested for further research.

  3. Global environmental effects of impact-generated aerosols: Results from a general circulation model: Revision 1

    SciTech Connect

    Covey, C.; Ghan, S.J.; Walton, J.J.; Weissman, P.R.

    1989-06-01

    Interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet would lead to substantial land surface cooling, according to our three-dimensional atmospheric general circulation model (GCM). This result is qualitatively similar to conclusions drawn from an earlier study that employed a one-dimensional atmospheric model, but in the GCM simulation the heat capacity of the oceans substantially mitigates land surface cooling, an effect that one-dimensional models cannot quantify. On the other hand, the low heat capacity of the GCM's land surface allows temperatures to drop more rapidly in the initial stage of cooling than in the one-dimensional model study. These two differences between three-dimensional and one-dimensional model simulations were noted previously in studies of ''nuclear winter; '' GCM-simulated climatic changes in the Alvarez-inspired scenario of ''asteroid/comet winter,'' however, are more severe than in ''nuclear winter'' because the assumed aerosol amount is large enough to intercept all sunlight falling on earth. Impacts of smaller objects -- which would occur much more frequently than the Cretaceous/Tertiary event deduced by Alvarez and coworkers -- could also lead to dramatic, though less severe, climatic changes, according to our GCM. Our conclusion is that it is difficult to imagine an asteroid or comet impact leading to anything approaching complete global freezing, but quite reasonable to assume that impacts at the Alvarez level, or even smaller, dramatically alter the climate in at least a ''patchy'' sense. 30 refs., 4 figs., 1 tab.

  4. Future climate of the Caribbean from a super-high-resolution atmospheric general circulation model

    NASA Astrophysics Data System (ADS)

    Hall, Trevor C.; Sealy, Andrea M.; Stephenson, Tannecia S.; Kusunoki, Shoji; Taylor, Michael A.; Chen, A. Anthony; Kitoh, Akio

    2013-07-01

    Present-day (1979-2003) and future (2075-2099) simulations of mean and extreme rainfall and temperature are examined using data from the Meteorological Research Institute super-high-resolution atmospheric general circulation model. Analyses are performed over the 20-km model grid for (1) a main Caribbean basin, (2) sub-regional zones, and (3) specific Caribbean islands. Though the model's topography underestimates heights over the eastern Caribbean, it captures well the present-day spatial and temporal variations of seasonal and annual climates. Temperature underestimations range from 0.1 °C to 2 °C with respect to the Japanese Reanalysis and the Climatic Research Unit datasets. The model also captures fairly well sub-regional scale variations in the rainfall climatology. End-of-century projections under the Intergovernmental Panel on Climate Change SRES A1B scenario indicate declines in rainfall amounts by 10-20 % for most of the Caribbean during the early (May-July) and late (August-October) rainy seasons relative to the 1979-2003 baselines. The early dry season (November-January) is also projected to get wetter in the far north and south Caribbean by approximately 10 %. The model also projects a warming of 2-3 °C over the Caribbean region. Analysis of future climate extremes indicate a 5-10 % decrease in the simple daily precipitation intensity but no significant change in the number of consecutive dry days for Cuba, Jamaica, southern Bahamas, and Haiti. There is also indication that the number of hot days and nights will significantly increase over the main Caribbean basin.

  5. Using Clustered Climate Regimes to Analyze and Compare Predictions from Fully Coupled General Circulation Models

    SciTech Connect

    Hoffman, Forrest M; Hargrove, William Walter; Erickson III, David J; Oglesby, Robert J

    2005-01-01

    Changes in Earth's climate in response to atmospheric greenhouse gas buildup impact the health of terrestrial ecosystems and the hydrologic cycle. The environmental conditions influential to plant and animal life are often mapped as ecoregions, which are land areas having similar combinations of environmental characteristics. This idea is extended to establish regions of similarity with respect to climatic characteristics that evolve through time using a quantitative statistical clustering technique called Multivariate Spatio-Temporal Clustering (MSTC). MSTC was applied to the monthly time series output from a fully coupled general circulation model (GCM) called the Parallel Climate Model (PCM). Results from an ensemble of five 99-yr Business-As-Usual (BAU) transient simulations from 2000 to 2098 were analyzed. MSTC establishes an exhaustive set of recurring climate regimes that form a 'skeleton' through the 'observations' (model output) throughout the occupied portion of the climate phase space formed by the characteristics being considered. MSTC facilitates direct comparison of ensemble members and ensemble and temporal averages since the derived climate regimes provide a basis for comparison. Moreover, by mapping all land cells to discrete climate states, the dynamic behavior of any part of the system can be studied by its time-varying sequence of climate state occupancy. MSTC is a powerful tool for model developers and environmental decision makers who wish to understand long, complex time series predictions of models. Strong predicted interannual trends were revealed in this analysis, including an increase in global desertification; a decrease in the cold, dry high-latitude conditions typical of North American and Asian winters; and significant warming in Antarctica and western Greenland.

  6. ENSO Bred Vectors in Coupled Ocean-Atmosphere General Circulation Models

    NASA Technical Reports Server (NTRS)

    Yang, S. C.; Cai, Ming; Kalnay, E.; Rienecker, M.; Yuan, G.; Toth, ZA.

    2004-01-01

    The breeding method has been implemented in the NASA Seasonal-to-Interannual Prediction Project (NSIPP) Coupled General Circulation Model (CGCM) with the goal of improving operational seasonal to interannual climate predictions through ensemble forecasting and data assimilation. The coupled instability as cap'tured by the breeding method is the first attempt to isolate the evolving ENSO instability and its corresponding global atmospheric response in a fully coupled ocean-atmosphere GCM. Our results show that the growth rate of the coupled bred vectors (BV) peaks at about 3 months before a background ENSO event. The dominant growing BV modes are reminiscent of the background ENSO anomalies and show a strong tropical response with wind/SST/thermocline interrelated in a manner similar to the background ENSO mode. They exhibit larger amplitudes in the eastern tropical Pacific, reflecting the natural dynamical sensitivity associated with the presence of the shallow thermocline. Moreover, the extratropical perturbations associated with these coupled BV modes reveal the variations related to the atmospheric teleconnection patterns associated with background ENSO variability, e.g. over the North Pacific and North America. A similar experiment was carried out with the NCEP/CFS03 CGCM. Comparisons between bred vectors from the NSIPP CGCM and NCEP/CFS03 CGCM demonstrate the robustness of the results. Our results strongly suggest that the breeding method can serve as a natural filter to identify the slowly varying, coupled instabilities in a coupled GCM, which can be used to construct ensemble perturbations for ensemble forecasts and to estimate the coupled background error covariance for coupled data assimilation.

  7. Short ensembles: An Efficient Method for Discerning Climate-relevant Sensitivities in Atmospheric General Circulation Models

    SciTech Connect

    Wan, Hui; Rasch, Philip J.; Zhang, Kai; Qian, Yun; Yan, Huiping; Zhao, Chun

    2014-09-08

    This paper explores the feasibility of an experimentation strategy for investigating sensitivities in fast components of atmospheric general circulation models. The basic idea is to replace the traditional serial-in-time long-term climate integrations by representative ensembles of shorter simulations. The key advantage of the proposed method lies in its efficiency: since fewer days of simulation are needed, the computational cost is less, and because individual realizations are independent and can be integrated simultaneously, the new dimension of parallelism can dramatically reduce the turnaround time in benchmark tests, sensitivities studies, and model tuning exercises. The strategy is not appropriate for exploring sensitivity of all model features, but it is very effective in many situations. Two examples are presented using the Community Atmosphere Model version 5. The first example demonstrates that the method is capable of characterizing the model cloud and precipitation sensitivity to time step length. A nudging technique is also applied to an additional set of simulations to help understand the contribution of physics-dynamics interaction to the detected time step sensitivity. In the second example, multiple empirical parameters related to cloud microphysics and aerosol lifecycle are perturbed simultaneously in order to explore which parameters have the largest impact on the simulated global mean top-of-atmosphere radiation balance. Results show that in both examples, short ensembles are able to correctly reproduce the main signals of model sensitivities revealed by traditional long-term climate simulations for fast processes in the climate system. The efficiency of the ensemble method makes it particularly useful for the development of high-resolution, costly and complex climate models.

  8. Evaluation of the Surface Representation of the Greenland Ice Sheet in a General Circulation Model

    NASA Technical Reports Server (NTRS)

    Cullather, Richard I.; Nowicki, Sophie M. J.; Zhao, Bin; Suarez, Max J.

    2014-01-01

    Simulated surface conditions of the Goddard Earth Observing System model, version 5 (GEOS 5) atmospheric general circulation model (AGCM) are examined for the contemporary Greenland Ice Sheet (GrIS). A surface parameterization that explicitly models surface processes including snow compaction, meltwater percolation and refreezing, and surface albedo is found to remedy an erroneous deficit in the annual net surface energy flux and provide an adequate representation of surface mass balance (SMB) in an evaluation using simulations at two spatial resolutions. The simulated 1980-2008 GrIS SMB average is 24.7+/-4.5 cm yr(- 1) water-equivalent (w.e.) at.5 degree model grid spacing, and 18.2+/-3.3 cm yr(- 1) w.e. for 2 degree grid spacing. The spatial variability and seasonal cycle of the simulation compare favorably to recent studies using regional climate models, while results from 2 degree integrations reproduce the primary features of the SMB field. In comparison to historical glaciological observations, the coarser resolution model overestimates accumulation in the southern areas of the GrIS, while the overall SMB is underestimated. These changes relate to the sensitivity of accumulation and melt to the resolution of topography. The GEOS-5 SMB fields contrast with available corresponding atmospheric models simulations from the Coupled Model Intercomparison Project (CMIP5). It is found that only a few of the CMIP5 AGCMs examined provide significant summertime runoff, a dominant feature of the GrIS seasonal cycle. This is a condition that will need to be remedied if potential contributions to future eustatic change from polar ice sheets are to be examined with GCMs.

  9. Snow Cover and Snow Mass Intercomparisons of General Circulation Models and Remotely Sensed Datasets.

    NASA Astrophysics Data System (ADS)

    Foster, James; Liston, Glen; Koster, Randy; Essery, Richard; Behr, Helga; Dumenil, Lydia; Verseghy, Diana; Thompson, Starly; Pollard, David; Cohen, Judah

    1996-02-01

    Confirmation of the ability of general circulation models (GCMs) to accurately represent snow cover and snow mass distributions is vital for climate studies. There must be a high degree of confidence that what is being predicted by the models is reliable, since realistic results cannot be assured unless they are tested against results from observed data or other available datasets. In this study, snow output from seven GCMs and passive-microwave snow data derived from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) are intercompared. National Oceanic and Atmospheric Administration satellite data are used as the standard of reference for snow extent observations and the U.S. Air Force snow depth climatology is used as the standard for snow mass. The reliability of the SMMR snow data needs to be verified, as well, because currently this is the only available dataset that allows for yearly and monthly variations in snow depth. [The GCMs employed in this investigation are the United Kingdom Meteorological Office, Hadley Centre GCM, the Max Planck Institute for Meteorology/University of Hamburg (ECHAM) GCM, the Canadian Climate Centre GCM, the National Center for Atmospheric Research (GENESIS) GCM, the Goddard Institute for Space Studies GCM, the Goddard Laboratory for Atmospheres GCM and the Goddard Coupled Climate Dynamics Group (AIRES) GCM.] Data for both North America and Eurasia are examined in an effort to assess the magnitude of spatial and temporal variations that exist between the standards of reference, the models, and the passive microwave data. Results indicate that both the models and SMMR represent seasonal and year-to-year snow distributions fairly well. The passive microwave data and several of the models, however, consistently underestimate snow mass, but other models overestimate the mass of snow on the ground. The models do a better job simulating winter and summer snow conditions than in the transition months. In general, the

  10. Potential future changes of the terrestrial ecosystem based on climate projections by eight general circulation models

    NASA Astrophysics Data System (ADS)

    Alo, Clement Aga; Wang, Guiling

    2008-03-01

    A number of previous modeling studies have assessed the implications of projected CO2-induced climate change for future terrestrial ecosystems. However, although current understanding of possible long-term response of vegetation to elevated CO2 and CO2-induced climate change in some geographical areas (e.g., the high-latitude regions) has been strengthened by dint of accumulating evidence from these past studies, it is still weak in others. This study examines the responses of global potential natural vegetation distribution, net primary production (NPP), and fire emissions to future changes in atmospheric CO2 concentration and climate using the National Center for Atmospheric Research Community Land Model's dynamic global vegetation model. The model is run to vegetative equilibrium (i.e., with respect to leaf area index (LAI) and vegetation coverage) driven with preindustrial climate and future climate near 2100, respectively, simulated by eight general circulation models (GCMs). The simulated potential vegetation under the preindustrial control mean climate (CO2 concentration held at 275 ppm) is compared with that under the SRESA1B 2100 mean climate (CO2 concentration stabilizes at 720 ppm beyond 2100). Simulated vegetation response ranges from mild changes of the fractional coverage of different plant functional types to the rather dramatic changes of dominant plant functional types. Although such response differs significantly across different GCM climate projections, a quite consistent spatial pattern emerges, characterized by a considerable poleward spread or shift of temperate and boreal forests in the Northern Hemisphere high latitudes, and a substantial degradation of vegetation type in the tropics (e.g., increase of drought deciduous trees coverage at the expense of evergreen trees) especially in portions of West and southern Africa and South America. Despite the widespread degradation of vegetation type in the tropics, NPP, and growing season LAI are

  11. The Local Balances of Vorticity and Heat for Blocking Anticyclones in a Spectral General Circulation Model.

    NASA Astrophysics Data System (ADS)

    Mullen, Steven L.

    1986-07-01

    Blocking anticyclones that appear in perpetual January simulations of a spectral general circulation model are examined. Blocks in three geographical regions are studied: the North Pacific, the North Atlantic and western North America. Local time-averaged balances of vorticity and heat are evaluated for composite cases of blocking. The following common relationships emerged from these budgets.The time-mean divergence term is, in general, a flat-order term in the vorticity balance throughout the troposphere and its pattern over severe orography is closely related to the underlying topography. Above the surface layer, the horizontal advection of time-mean absolute vorticity by the mean wind mainly balances the divergence term with the net effect of the time-mean vorticity forcing being a tendency for the blocking pattern to propagate downstream. The transient eddy vorticity transports act to shift the block upstream and hence they mainly offset the downstream tendency due to the time-mean flow; the magnitude of the eddy vorticity term is typically one-third to one-half that of the divergence or advection terms alone. Frictional dissipation is negligible everywhere except near the ground where it primarily offsets the divergence term.The horizontal advection of the time-mean temperature field by the mean wind throughout the troposphere is a first-order term in the beat balance and is mainly responsible for maintaining the block's thermal perturbations; it is predominately balanced by adiabatic heating in the free troposphere and by diabatic heating near the surface. Transient eddy heat transports act to dissipate the block's thermal perturbations at all levels, while diabatic heating does not exhibit a systematic relationship with the temperature field at any level.A quasi-geostrophic diagnosis of the ageostrophic motion field suggests that dynamical processes which strongly affect the vorticity balance may be more important to the maintenance of model blocks than

  12. Modeling cellular processes in 3D.

    PubMed

    Mogilner, Alex; Odde, David

    2011-12-01

    Recent advances in photonic imaging and fluorescent protein technology offer unprecedented views of molecular space-time dynamics in living cells. At the same time, advances in computing hardware and software enable modeling of ever more complex systems, from global climate to cell division. As modeling and experiment become more closely integrated we must address the issue of modeling cellular processes in 3D. Here, we highlight recent advances related to 3D modeling in cell biology. While some processes require full 3D analysis, we suggest that others are more naturally described in 2D or 1D. Keeping the dimensionality as low as possible reduces computational time and makes models more intuitively comprehensible; however, the ability to test full 3D models will build greater confidence in models generally and remains an important emerging area of cell biological modeling.

  13. Eyes on the Earth 3D

    NASA Technical Reports Server (NTRS)

    Kulikov, anton I.; Doronila, Paul R.; Nguyen, Viet T.; Jackson, Randal K.; Greene, William M.; Hussey, Kevin J.; Garcia, Christopher M.; Lopez, Christian A.

    2013-01-01

    Eyes on the Earth 3D software gives scientists, and the general public, a realtime, 3D interactive means of accurately viewing the real-time locations, speed, and values of recently collected data from several of NASA's Earth Observing Satellites using a standard Web browser (climate.nasa.gov/eyes). Anyone with Web access can use this software to see where the NASA fleet of these satellites is now, or where they will be up to a year in the future. The software also displays several Earth Science Data sets that have been collected on a daily basis. This application uses a third-party, 3D, realtime, interactive game engine called Unity 3D to visualize the satellites and is accessible from a Web browser.

  14. The Wind, Temperature, and Surface Pressure on Pluto from a Pluto General Circulation Model

    NASA Astrophysics Data System (ADS)

    Zalucha, A. M.; Gulbis, A.

    2011-12-01

    A variety of methods have been used to derive Pluto's atmospheric temperature, composition, and surface pressure from spectra and stellar occultation data, while wind is less easily determined. Gravity wave dissipation has been investigated [1] in the 18 March 2007 stellar occultation dataset [2], demonstrating that wind is occurring in the form of perturbations about a mean. Rossby waves have also been proposed [2] as an explanation to the 2007 dataset; however the method was used incorrectly. General circulation models (GCMs) are a ubiquitous tool in the field of planetary atmospheres to solve for the global state of the atmosphere in a physically consistent manner, but only recently have they began to be developed for Pluto. We use a Pluto version of the Massachusetts Institute of Technology (MIT) GCM to solve for the first time for wind, temperature, and surface pressure globally in Pluto's atmosphere. The Pluto version of the MIT GCM (PGCM) uses the MIT GCM dynamical core [3] with a radiative-conductive model [4]. It includes vertical thermal conduction and non-local thermodynamic equilibrium heating and cooling by methane at 3.3 um and 7.6 um, respectively. We perform a parameter sweep with methane volume mixing ratios of 0.2, 0.6, and 1% and initial global mean surface pressures of 6-26 ubar. We ran the model from rest starting in the model year 1973. We compared the PGCM results with occultation data from the years 1988, 2002, 2006, and 2007. Model light curves were calculated from the PGCM temperature output (averaged at 90 day intervals) at the corresponding date and Pluto latitudes of each occultation. The match between data and PGCM is better than between data and the radiative-conductive equilibrium solution (i.e. no wind), but the PGCM light curves contain wave-like features while the data do not. We do not believe that this feature represents an atmospheric wave; rather, it is numerical noise known to occur in 2D GCMs. The PGCM-predicted zonal

  15. PB3D: A new code for edge 3-D ideal linear peeling-ballooning stability

    NASA Astrophysics Data System (ADS)

    Weyens, T.; Sánchez, R.; Huijsmans, G.; Loarte, A.; García, L.

    2017-02-01

    A new numerical code PB3D (Peeling-Ballooning in 3-D) is presented. It implements and solves the intermediate-to-high-n ideal linear magnetohydrodynamic stability theory extended to full edge 3-D magnetic toroidal configurations in previous work [1]. The features that make PB3D unique are the assumptions on the perturbation structure through intermediate-to-high mode numbers n in general 3-D configurations, while allowing for displacement of the plasma edge. This makes PB3D capable of very efficient calculations of the full 3-D stability for the output of multiple equilibrium codes. As first verification, it is checked that results from the stability code MISHKA [2], which considers axisymmetric equilibrium configurations, are accurately reproduced, and these are then successfully extended to 3-D configurations, through comparison with COBRA [3], as well as using checks on physical consistency. The non-intuitive 3-D results presented serve as a tentative first proof of the capabilities of the code.

  16. A general circulation model study of the global carbonaceous aerosol distribution

    NASA Astrophysics Data System (ADS)

    Cooke, W. F.; Ramaswamy, V.; Kasibhatla, P.

    2002-08-01

    Atmospheric distributions of carbonaceous aerosols are simulated using the Geophysical Fluid Dynamics Laboratory SKYHI general circulation model (GCM) (latitude-longitude resolution of ~3° × 3.6°). A number of systematic analyses are conducted to investigate the seasonal and interannual variability of the concentrations at specific locations and to investigate the sensitivity of the distributions to various physical parameters. Comparisons are made with several observational data sets. At four specific sites (Mace Head, Mauna Loa, Sable Island, and Bondville) the monthly mean measurements of surface concentrations of black carbon made over several years reveal that the model simulation registers successes as well as failures. Comparisons are also made with averages of measurements made over varying time periods, segregated by geography and rural/remote locations. Generally, the mean measured remote surface concentrations exceed those simulated. Notwithstanding the large variability in measurements and model simulations, the simulations of both black and organic carbon tend to be within about a factor of 2 at a majority of the sites. There are major challenges in conducting comparisons with measurements due to inadequate sampling at some sites, the generally short length of the observational record, and different methods used for estimating the black and organic carbon amounts. The interannual variability in the model and in the few such measurements available points to the need for doing multiyear modeling and to the necessity of comparing with long-term measurements. There are very few altitude profile measurements; notwithstanding the large uncertainties, the present comparisons suggest an overestimation by the model in the free troposphere. The global column burdens of black and organic carbon in the present standard model integration are lower than in previous studies and thus could be regarded as approximately bracketing a lower end of the simulated

  17. 3D Spectroscopy in Astronomy

    NASA Astrophysics Data System (ADS)

    Mediavilla, Evencio; Arribas, Santiago; Roth, Martin; Cepa-Nogué, Jordi; Sánchez, Francisco

    2011-09-01

    Preface; Acknowledgements; 1. Introductory review and technical approaches Martin M. Roth; 2. Observational procedures and data reduction James E. H. Turner; 3. 3D Spectroscopy instrumentation M. A. Bershady; 4. Analysis of 3D data Pierre Ferruit; 5. Science motivation for IFS and galactic studies F. Eisenhauer; 6. Extragalactic studies and future IFS science Luis Colina; 7. Tutorials: how to handle 3D spectroscopy data Sebastian F. Sánchez, Begona García-Lorenzo and Arlette Pécontal-Rousset.

  18. Spherical 3D isotropic wavelets

    NASA Astrophysics Data System (ADS)

    Lanusse, F.; Rassat, A.; Starck, J.-L.

    2012-04-01

    Context. Future cosmological surveys will provide 3D large scale structure maps with large sky coverage, for which a 3D spherical Fourier-Bessel (SFB) analysis in spherical coordinates is natural. Wavelets are particularly well-suited to the analysis and denoising of cosmological data, but a spherical 3D isotropic wavelet transform does not currently exist to analyse spherical 3D data. Aims: The aim of this paper is to present a new formalism for a spherical 3D isotropic wavelet, i.e. one based on the SFB decomposition of a 3D field and accompany the formalism with a public code to perform wavelet transforms. Methods: We describe a new 3D isotropic spherical wavelet decomposition based on the undecimated wavelet transform (UWT) described in Starck et al. (2006). We also present a new fast discrete spherical Fourier-Bessel transform (DSFBT) based on both a discrete Bessel transform and the HEALPIX angular pixelisation scheme. We test the 3D wavelet transform and as a toy-application, apply a denoising algorithm in wavelet space to the Virgo large box cosmological simulations and find we can successfully remove noise without much loss to the large scale structure. Results: We have described a new spherical 3D isotropic wavelet transform, ideally suited to analyse and denoise future 3D spherical cosmological surveys, which uses a novel DSFBT. We illustrate its potential use for denoising using a toy model. All the algorithms presented in this paper are available for download as a public code called MRS3D at http://jstarck.free.fr/mrs3d.html

  19. General atmospheric circulation driven by polar and diurnal surface temperature variations.

    NASA Technical Reports Server (NTRS)

    Bohachevsky, I. O.

    1973-01-01

    Described is a global circulation model for the Venus atmosphere that includes the effects of both polar cooling and diurnal temperature variation. It is based on a linearized Boussinesq approximation and boundary conditions derived from theoretical and empirical considerations. The time-dependent, three-dimensional flow field is deduced without any a priori assumptions about its configuration. Results show that the mean atmospheric motions are essentially zonal in a narrow belt near the equator and change to become meridional over most of the globe. The circulation pattern is not symmetrical and rotates about the polar axis of the planet with the period of the solar day.

  20. Performance of a reconfigured atmospheric general circulation model at low resolution

    NASA Astrophysics Data System (ADS)

    Wen, Xinyu; Zhou, Tianjun; Wang, Shaowu; Wang, Bin; Wan, Hui; Li, Jian

    2007-07-01

    Paleoclimate simulations usually require model runs over a very long time. The fast integration version of a state-of-the-art general circulation model (GCM), which shares the same physical and dynamical processes but with reduced horizontal resolution and increased time step, is usually developed. In this study, we configure a fast version of an atmospheric GCM (AGCM), the Grid Atmospheric Model of IAP/LASG (Institute of Atmospheric Physics/State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics), at low resolution (GAMIL-L, hereafter), and compare the simulation results with the NCEP/NCAR reanalysis and other data to examine its performance. GAMIL-L, which is derived from the original GAMIL, is a finite difference AGCM with 72×40 grids in longitude and latitude and 26 vertical levels. To validate the simulated climatology and variability, two runs were achieved. One was a 60-year control run with fixed climatological monthly sea surface temperature (SST) forcing, and the other was a 50-yr (1950 2000) integration with observational time-varying monthly SST forcing. Comparisons between these two cases and the reanalysis, including intra-seasonal and inter-annual variability are also presented. In addition, the differences between GAMIL-L and the original version of GAMIL are also investigated. The results show that GAMIL-L can capture most of the large-scale dynamical features of the atmosphere, especially in the tropics and mid latitudes, although a few deficiencies exist, such as the underestimated Hadley cell and thereby the weak strength of the Asia summer monsoon. However, the simulated mean states over high latitudes, especially over the polar regions, are not acceptable. Apart from dynamics, the thermodynamic features mainly depend upon the physical parameterization schemes. Since the physical package of GAMIL-L is exactly the same as the original high-resolution version of GAMIL, in which the NCAR Community

  1. Evaluation of Cloud Parameterizations in a High Resolution Atmospheric General Circulation Model Using ARM Data

    SciTech Connect

    Govindasamy, B; Duffy, P

    2002-04-12

    Typical state of the art atmospheric general circulation models used in climate change studies have horizontal resolution of approximately 300 km. As computing power increases, many climate modeling groups are working toward enhancing the resolution of global models. An important issue that arises when resolution of a model is changed is whether cloud and convective parameterizations, which were developed for use at coarser resolutions, will need to be reformulated or re-tuned. We propose to investigate this issue and specifically cloud statistics using ARM data. The data streams produced by highly instrumented sections of Cloud and Radiation Testbeds (CART) of ARM program will provide a significant aid in the evaluation of cloud and convection parameterization in high-resolution models. Recently, we have performed multiyear global-climate simulations at T170 and T239 resolutions, corresponding to grid cell sizes of 0.7{sup 0} and 0.5{sup 0} respectively, using the NCAR Community Climate Model. We have also a performed climate change simulation at T170. On the scales of a T42 grid cell (300 km) and larger, nearly all quantities we examined in T170 simulation agree better with observations in terms of spatial patterns than do results in a comparable simulation at T42. Increasing the resolution to T239 brings significant further improvement. At T239, the high-resolution model grid cells approach the dimensions of the highly instrumented sections of ARM Cloud and Radiation Testbed (CART) sites. We propose to form a cloud climatology using ARM data for its CART sites and evaluate cloud statistics of the NCAR Community Atmosphere Model (CAM) at higher resolutions over those sites using this ARM cloud climatology. We will then modify the physical parameterizations of CAM for better agreement with ARM data. We will work closely with NCAR in modifying the parameters in cloud and convection parameterizations for the high-resolution model. Our proposal to evaluate the cloud

  2. Assessment of Atmosphere-Ocean General Circulation Model Simulations of Winter Northern Hemisphere Atmospheric Blocking

    NASA Astrophysics Data System (ADS)

    Vial, Jessica; Osborn, Tim

    2010-05-01

    Characterized by their persistence and quasi-stationary features, large-scale atmospheric blocking are often responsible for extreme weather events, which can have enormous impacts on human life, economy and environment e.g. European heat wave in summer 2003. Therefore, diagnostics of the present-day climate and future projections of potential changes in blocking-related extreme events are essential for risk management and adaptation planning. This study focuses on assessing the ability of six coupled Atmosphere-Ocean General Circulation Models (AOGCMs) to simulate large-scale winter atmospheric blocking in the Northern Hemisphere for the present-day climate (1957-1999). A modified version of the Tibaldi and Molteni (1990)'s blocking index, which measures the strength of the average westerly flow in the mid-latitudes, is applied to daily averaged 500 hPa geopotential height output from the climate models. ERA-40 re-analysis atmospheric data have also been used over the same time period to verify the models' results. The two preferred regions of blocking development, in the Euro-Atlantic and North Pacific, are well captured by most of the models. However, the prominent error in blocking simulations, according to a number of previous model assessments, consists of an underestimation of the total frequency of blocking episodes over both regions. A more detailed analysis of blocking frequency as a function of duration revealed that this error was due to an insufficient number of medium spells and long-lasting episodes, and a shift in blocking lifetime distributions towards shorter blocks, while short-lived blocking events (between 5 and 8 days) tend to be overestimated. The impact of models' systematic errors on blocking simulations has been analyzed, and results suggest that there is a primary need to reduce the time-mean bias to improve the representation of blocking in climate models. The underestimated high-frequency variability of the transient eddies embedded in

  3. The Madden-Julian oscillation in ECHAM4 coupled and uncoupled general circulation models

    DOE PAGES

    Sperber, Kenneth R.; Gualdi, Silvio; Legutke, Stephanie; ...

    2005-06-29

    The Madden-Julian oscillation (MJO) dominates tropical variability on timescales of 30–70 days. During the boreal winter/spring, it is manifested as an eastward propagating disturbance, with a strong convective signature over the eastern hemisphere. The space–time structure of the MJO is analyzed using simulations with the ECHAM4 atmospheric general circulation model run with observed monthly mean sea-surface temperatures (SSTs), and coupled to three different ocean models. The coherence of the eastward propagation of MJO convection is sensitive to the ocean model to which ECHAM4 is coupled. For ECHAM4/OPYC and ECHO-G, models for which ~100 years of daily data is available, Montemore » Carlo sampling indicates that their metrics of eastward propagation are different at the 1% significance level. The flux-adjusted coupled simulations, ECHAM4/OPYC and ECHO-G, maintain a more realistic mean-state, and have a more realistic MJO simulation than the nonadjusted scale interaction experiment (SINTEX) coupled runs. The SINTEX model exhibits a cold bias in Indian Ocean and tropical West Pacific Ocean sea-surface temperature of ~0.5°C. This cold bias affects the distribution of time-mean convection over the tropical eastern hemisphere. Furthermore, the eastward propagation of MJO convection in this model is not as coherent as in the two models that used flux adjustment or when compared to an integration of ECHAM4 with prescribed observed SST. This result suggests that simulating a realistic basic state is at least as important as air–sea interaction for organizing the MJO. While all of the coupled models simulate the warm (cold) SST anomalies that precede (succeed) the MJO convection, the interaction of the components of the net surface heat flux that lead to these anomalies are different over the Indian Ocean. The ECHAM4/OPYC model in which the atmospheric model is run at a horizontal resolution of T42, has eastward propagating zonal wind anomalies and latent heat

  4. The Improvement of The Absorption Process Using A Computational Optimization in An Atmospheric General Circulation Model

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Miho; Nakajima, Teruyuki

    2009-03-01

    This study improves the gaseous absorption process scheme of the broadband radiative transfer code "mstrnX" that was developed by the Center for Climate System Research (CCSR) for efficient calculation of atmospheric radiative transfer in the general circulation models. This scheme is adopted the optimization method to decrease the number of quadrature points for wavenumber integration by using the correlated k-distribution method and to increase the computational efficiency in each spectral band. The objective function of the standard version is defined as the sum of errors in radiation fluxes and heating rate in six standard atmospheres, and we added six other atmospheric profiles in the doubling CO2 condition for the doubling CO2 version. The preferable errors of radiative flux is thought about 1-2 W/m2, however, it is desirable that the errors of radiative forcing of CO2 is less than 0.3 W/m2. So, we improve the doubling CO2 version to calculate the radiative forcings precisely. When integration points and weights are determined in each band, we select the results whose errors of the instantaneous radiative forcing at TOA, troposphere and surface are under 0.2 W/m2. Moreover, radiative forcings of other WMGHGs are considered as same as CO2. Then, we build a global warming version with 29 bands and 111 integration points. In this version, the maximum radiation flux error is less than 0.6 W/m2 in LW and 0.45 W/m2 in SW at all altitude, and the maximum heating rate error is less than 0.2 K/day in the troposphere and the stratosphere for any standard atmosphere. The radiative forcing can be evaluated with small errors not exceeding one standard deviation of samples of forcings from the AOGCMs except for the changes of N2O+CFCs case in the RTMIP experiment. It is found that the proposed optimization method is effective in maintaining a low computational cost with accuracy good enough for dynamical simulations with a GCM. MstrnX is now available from the Open

  5. Cloud Radiation Forcings and Feedbacks: General Circulation Model Tests and Observational Validation

    NASA Technical Reports Server (NTRS)

    Lee,Wan-Ho; Iacobellis, Sam F.; Somerville, Richard C. J.

    1997-01-01

    Using an atmospheric general circulation model (the National Center for Atmospheric Research Community Climate Model: CCM2), the effects on climate sensitivity of several different cloud radiation parameterizations have been investigated. In addition to the original cloud radiation scheme of CCM2, four parameterizations incorporating prognostic cloud water were tested: one version with prescribed cloud radiative properties and three other versions with interactive cloud radiative properties. The authors' numerical experiments employ perpetual July integrations driven by globally constant sea surface temperature forcings of two degrees, both positive and negative. A diagnostic radiation calculation has been applied to investigate the partial contributions of high, middle, and low cloud to the total cloud radiative forcing, as well as the contributions of water vapor, temperature, and cloud to the net climate feedback. The high cloud net radiative forcing is positive, and the middle and low cloud net radiative forcings are negative. The total net cloud forcing is negative in all of the model versions. The effect of interactive cloud radiative properties on global climate sensitivity is significant. The net cloud radiative feedbacks consist of quite different shortwave and longwave components between the schemes with interactive cloud radiative properties and the schemes with specified properties. The increase in cloud water content in the warmer climate leads to optically thicker middle- and low-level clouds and in turn to negative shortwave feedbacks for the interactive radiative schemes, while the decrease in cloud amount simply produces a positive shortwave feedback for the schemes with a specified cloud water path. For the longwave feedbacks, the decrease in high effective cloudiness for the schemes without interactive radiative properties leads to a negative feedback, while for the other cases, the longwave feedback is positive. These cloud radiation

  6. Atmospheric Torques on the Solid Earth and Oceans Based on the GEOS-1 General Circulation Model

    NASA Technical Reports Server (NTRS)

    Sanchez, Braulio V.; Au, Andrew Y.

    1998-01-01

    The GEOS-1 general circulation model has been used to compute atmospheric torques on the oceans and solid Earth for the period 1980-1995. The time series for the various torque components have been analyzed by means of Fourier transform techniques. It was determined that the wind stress torque over land is more powerful than the wind stress torque over water by 55%, 42%, and 80% for the x, y, and z components respectively. This is mainly the result of power in the high frequency range. The pressure torques due to polar flattening, equatorial ellipticity, marine geoid, and continental orography were computed. The orographic or "mountain torque" components are more powerful than their wind stress counterparts (land plus ocean) by 231% (x), 191% (y), and 77% (z). The marine pressure torques due to geoidal undulations are much smaller than the orographic ones, as expected. They are only 3% (x), 4% (y), and 5% (z) of the corresponding mountain torques. The geoidal pressure torques are approximately equal in magnitude to those produced by the equatorial ellipticity of the Earth. The pressure torque due to polar flattening makes the largest contributions to the atmospheric torque budget. It has no zonal component, only equatorial ones. Most of the power of the latter, between 68% and 69%, is found in modes with periods under 15 days. The single most powerful mode has a period of 361 days. The gravitational torque ranks second in power only to the polar flattening pressure torque. Unlike the former, it does produce a zonal component, albeit much smaller (1%) than the equatorial ones. The gravitational and pressure torques have opposite signs, therefore, the gravitational torque nullifies 42% of the total pressure torque. Zonally, however, the gravitational torque amounts to only 6% of the total pressure torque. The power budget for the total atmospheric torque yields 7595 and 7120 Hadleys for the equatorial components and 966 Hadleys for the zonal. The x-component exhibits

  7. Variable-resolution frameworks for the simulation of tropical cyclones in global atmospheric general circulation models

    NASA Astrophysics Data System (ADS)

    Zarzycki, Colin

    The ability of atmospheric General Circulation Models (GCMs) to resolve tropical cyclones in the climate system has traditionally been difficult. The challenges include adequately capturing storms which are small in size relative to model grids and the fact that key thermodynamic processes require a significant level of parameterization. At traditional GCM grid spacings of 50-300 km tropical cyclones are severely under-resolved, if not completely unresolved. This thesis explores a variable-resolution global model approach that allows for high spatial resolutions in areas of interest, such as low-latitude ocean basins where tropical cyclogenesis occurs. Such GCM designs with multi-resolution meshes serve to bridge the gap between globally-uniform grids and limited area models and have the potential to become a future tool for regional climate assessments. A statically-nested, variable-resolution option has recently been introduced into the Department of Energy/National Center for Atmospheric Research (DoE/NCAR) Community Atmosphere Model's (CAM) Spectral Element (SE) dynamical core. Using an idealized tropical cyclone test, variable-resolution meshes are shown to significantly lessen computational requirements in regional GCM studies. Furthermore, the tropical cyclone simulations are free of spurious numerical errors at the resolution interfaces. Utilizing aquaplanet simulations as an intermediate test between idealized simulations and fully-coupled climate model runs, climate statistics within refined patches are shown to be well-matched to globally-uniform simulations of the same grid spacing. Facets of the CAM version 4 (CAM4) subgrid physical parameterizations are likely too scale sensitive for variable-resolution applications, but the newer CAM5 package is vastly improved in performance at multiple grid spacings. Multi-decadal simulations following 'Atmospheric Model Intercomparison Project' protocols have been conducted with variable-resolution grids. Climate

  8. Climatology and natural variability of the global hydrologic cycle in the GLA atmospheric general circulation model

    NASA Technical Reports Server (NTRS)

    Lau, K.-M.; Mehta, V. M.; Sud, Y. C.; Walker, G. K.

    1994-01-01

    Time average climatology and low-frequency variabilities of the global hydrologic cycle (GHC) in the Goddard Laboratory for Atmospheres (GLA) general circulation model (GCM) were investigated in the present work. A 730-day experiment was conducted with the GLA GCM forced by insolation, sea surface temperature, and ice-snow undergoing climatological annual cycles. Ifluences of interactive soil moisture on time average climatology and natural variability of the GHC were also investigated by conducting 365-day experiments with and without interactive soil moisture. Insolation, sea surface temperature, and ice-snow were fixed at their July levels in the latter two experiments. Results show that the model's time average hydrologic cycle variables for July in all three experiments agree reasonably well with observations. Except in the case of precipitable water, the zonal average climates of the annual cycle experiment and the two perpetual July experiments are alike, i.e., their differences are within limits of the natural variability of the model's climate. Statistics of various components of the GHC, i.e., water vapor, evaporation, and precipitation, are significantly affected by the presence of interactive soil moisture. A long-term trend is found in the principal empirical modes of variability of ground wetness, evaporation, and sensible heat. Dominant modes of variability of these quantities over land are physically consistent with one another and with land surface energy balance requirements. The dominant mode of precipitation variability is found to be closely related to organized convection over the tropical western Pacific Ocean. The precipitation variability has timescales in the range of 2 to 3 months and can be identified with the stationary component of the Madden-Julian Oscillation. The precipitation mode is not sensitive to the presence of interactive soil moisture but is closely linked to both the rotational and divergent components of atmospheric

  9. A dry deposition parameterization for sulfur oxides in a chemistry and general circulation model

    NASA Astrophysics Data System (ADS)

    Ganzeveld, Laurens; Lelieveld, Jos; Roelofs, Geert-Jan

    1998-03-01

    A dry deposition scheme, originally developed to calculate the deposition velocities for the trace gases O3, NO2, NO, and HNO3 in the chemistry and general circulation European Centre Hamburg Model (ECHAM), is extended to sulfur dioxide (SO2) and sulfate (SO42-). In order to reduce some of the shortcomings of the previous model version a local surface roughness and a more realistic leaf area index (LAI), derived from a high-resolution ecosystem database are introduced. The current model calculates the deposition velocities from the aerodynamic resistance, a quasi-laminary boundary layer resistance and a surface resistance of the surface cover, e.g., snow/ice, bare soil, vegetation, wetted surfaces, and ocean. The SO2 deposition velocity over vegetated surfaces is calculated as a function of the vegetation activity, the canopy wetness, turbulent transport through the canopy to the soil, and uptake by the soil. The soil resistance is explicitly calculated from the relative humidity and the soil pH, derived from a high-resolution global soil pH database. The snow/ice resistance of SO2 is a function of temperature. The SO2 deposition velocity over the oceans is controlled by turbulence. The sulfate deposition velocity is calculated considering diffusion, impaction, and sedimentation. Over sea surfaces the effect of bubble bursting, causing the breakdown of the quasi-laminary boundary layer, scavenging of the sulfate aerosol by sea spray, and aerosol growth due to high local relative humidities are considered. An integrated sulfate deposition velocity is calculated, applying a unimodal mass size distribution over land and a bimodal mass size distribution over sea. The calculated sulfate deposition velocity is about an order of magnitude larger than that based on a monodisperse aerosol, which is often applied in chemistry-transport models. Incorporation of the new dry deposition scheme in the ECHAM model yields significant relative differences (up to ˜50%) in mass flux

  10. Aerosol indirect effects -- general circulation model intercomparison and evaluation with satellite data

    SciTech Connect

    Quaas, Johannes; Ming, Yi; Menon, Surabi; Takemura, Toshihiko; Wang, Minghuai; Penner, Joyce E.; Gettelman, Andrew; Lohmann, Ulrike; Bellouin, Nicolas; Boucher, Olivier; Sayer, Andrew M.; Thomas, Gareth E.; McComiskey, Allison; Feingold, Graham; Hoose, Corinna; Kristjansson, Jon Egill; Liu, Xiaohong; Balkanski, Yves; Donner, Leo J.; Ginoux, Paul A.; Stier, Philip; Feichter, Johann; Sednev, Igor; Bauer, Susanne E.; Koch, Dorothy; Grainger, Roy G.; Kirkevag, Alf; Iversen, Trond; Seland, Oyvind; Easter, Richard; Ghan, Steven J.; Rasch, Philip J.; Morrison, Hugh; Lamarque, Jean-Francois; Iacono, Michael J.; Kinne, Stefan; Schulz, Michael

    2009-04-10

    Aerosol indirect effects continue to constitute one of the most important uncertainties for anthropogenic climate perturbations. Within the international AEROCOM initiative, the representation of aerosol-cloud-radiation interactions in ten different general circulation models (GCMs) is evaluated using three satellite datasets. The focus is on stratiform liquid water clouds since most GCMs do not include ice nucleation effects, and none of the model explicitly parameterizes aerosol effects on convective clouds. We compute statistical relationships between aerosol optical depth (Ta) and various cloud and radiation quantities in a manner that is consistent between the models and the satellite data. It is found that the model-simulated influence of aerosols on cloud droplet number concentration (Nd) compares relatively well to the satellite data at least over the ocean. The relationship between Ta and liquid water path is simulated much too strongly by the models. It is shown that this is partly related to the representation of the second aerosol indirect effect in terms of autoconversion. A positive relationship between total cloud fraction (fcld) and Ta as found in the satellite data is simulated by the majority of the models, albeit less strongly than that in the satellite data in most of them. In a discussion of the hypotheses proposed in the literature to explain the satellite-derived strong fcld - Ta relationship, our results indicate that none can be identified as unique explanation. Relationships similar to the ones found in satellite data between Ta and cloud top temperature or outgoing long-wave radiation (OLR) are simulated by only a few GCMs. The GCMs that simulate a negative OLR - Ta relationship show a strong positive correlation between Ta and fcld The short-wave total aerosol radiative forcing as simulated by the GCMs is strongly influenced by the simulated anthropogenic fraction of Ta, and parameterisation assumptions such as a lower bound on Nd

  11. Atmospheric Torques on the Solid Earth and Oceans Based on the GEOS-1 General Circulation Model

    NASA Technical Reports Server (NTRS)

    Sanchez, Braulio

    1999-01-01

    The GEOS-1 general circulation model has been used to compute atmospheric torques on the oceans and solid Earth for the period 1980-1995. The time series for the various torque components have been analyzed by means of Fourier transform techniques. It was determined that the wind stress torque over land is more powerful than the wind stress torque over water by 55\\%, 42\\%, and 80\\t for the x, y, and z components respectively. This is mainly the result of power in the high frequency range. The pressure torques due to polar flattening, equatorial ellipticity, marine geoid, and continental orography were computed. The orographic or "mountain torque" components are more powerful than their wind stress counterparts (land plus ocean) by 231\\% (x), 191\\% (y), and 77\\% (z). The marine pressure torques due to geoidal undulations are much smaller than the orographic ones, as expected. They are only 3\\% (x), 4\\% (y), and 5\\% (z) of the corresponding mountain torques. The geoidal pressure torques are approximately equal in magnitude to those produced by the equatorial ellipticity of the Earth. The pressure torque due to polar flattening makes the largest contributions to the atmospheric'torque budget. It has no zonal component, only equatorial ones. Most of the power of the latter, between 68\\% and 69 %, is found in modes with periods under 15 days. The single most powerful mode has a period of 361 days. The gravitational torque ranks second in power only to the polar flattening pressure torque. Unlike the former, it does produce a zonal component, albeit much smaller (1\\ ) than the equatorial ones. The gravitational and pressure torques have opposite signs, therefore, the gravitational torque nullifies 42\\% of the total pressure torque. Zonally, however, the gravitational torque amounts to only 6\\% of the total pressure torque. The power budget for the total atmospheric torque yields 7595 and 7120 Hadleys for the equatorial components and 966 Hadleys for the

  12. 3D Elevation Program—Virtual USA in 3D

    USGS Publications Warehouse

    Lukas, Vicki; Stoker, J.M.

    2016-04-14

    The U.S. Geological Survey (USGS) 3D Elevation Program (3DEP) uses a laser system called ‘lidar’ (light detection and ranging) to create a virtual reality map of the Nation that is very accurate. 3D maps have many uses with new uses being discovered all the time.  

  13. Technical Report Series on Global Modeling and Data Assimilation. Volume 16; Filtering Techniques on a Stretched Grid General Circulation Model

    NASA Technical Reports Server (NTRS)

    Takacs, Lawrence L.; Sawyer, William; Suarez, Max J. (Editor); Fox-Rabinowitz, Michael S.

    1999-01-01

    This report documents the techniques used to filter quantities on a stretched grid general circulation model. Standard high-latitude filtering techniques (e.g., using an FFT (Fast Fourier Transformations) to decompose and filter unstable harmonics at selected latitudes) applied on a stretched grid are shown to produce significant distortions of the prognostic state when used to control instabilities near the pole. A new filtering technique is developed which accurately accounts for the non-uniform grid by computing the eigenvectors and eigenfrequencies associated with the stretching. A filter function, constructed to selectively damp those modes whose associated eigenfrequencies exceed some critical value, is used to construct a set of grid-spaced weights which are shown to effectively filter without distortion. Both offline and GCM (General Circulation Model) experiments are shown using the new filtering technique. Finally, a brief examination is also made on the impact of applying the Shapiro filter on the stretched grid.

  14. Troposphere-stratosphere (surface-55 km) monthly winter general circulation statistics for the Northern Hemisphere Four year averages

    NASA Technical Reports Server (NTRS)

    Geller, M. A.; Wu, M.-F.; Gelman, M. E.

    1983-01-01

    In response to theoretically predicted anthropogenic depletion of stratospheric ozone, there has been, in recent years, an increased effort in stratospheric modeling. For comparison between models and observations, it is not sufficient to only compare the morphology of model-generated parameters with observed parameter values. Model-generated statistics should also be compared with observation. It is one of the objectives of the present investigation to discuss a data set which can be used for this purpose for the Northern Hemisphere troposphere and stratosphere. However, the investigation is mainly concerned with a presentation of some of the general circulation statistics derived with the aid of the data set. Attention is given to winter monthly general circulation statistics which were derived from four years of daily 1200 GMT NOAA/NMC Northern Hemisphere analyses.

  15. 3D Kitaev spin liquids

    NASA Astrophysics Data System (ADS)

    Hermanns, Maria

    The Kitaev honeycomb model has become one of the archetypal spin models exhibiting topological phases of matter, where the magnetic moments fractionalize into Majorana fermions interacting with a Z2 gauge field. In this talk, we discuss generalizations of this model to three-dimensional lattice structures. Our main focus is the metallic state that the emergent Majorana fermions form. In particular, we discuss the relation of the nature of this Majorana metal to the details of the underlying lattice structure. Besides (almost) conventional metals with a Majorana Fermi surface, one also finds various realizations of Dirac semi-metals, where the gapless modes form Fermi lines or even Weyl nodes. We introduce a general classification of these gapless quantum spin liquids using projective symmetry analysis. Furthermore, we briefly outline why these Majorana metals in 3D Kitaev systems provide an even richer variety of Dirac and Weyl phases than possible for electronic matter and comment on possible experimental signatures. Work done in collaboration with Kevin O'Brien and Simon Trebst.

  16. The maximum overlap method: A general and efficient scheme for reducing basis sets. Application to the generation of approximate AO's for the 3 d transition metal atoms and ions

    NASA Astrophysics Data System (ADS)

    Francisco, E.; Seijo, L.; Pueyo, L.

    1986-07-01

    The method of maximum overlap, often applied to the problem of basis set reduction, is formulated in terms of weighted least squares with orthogonality restrictions. An analytical solution for the linear parameters of the reduced set is given. In this form, the method is a general and efficient scheme for reducing basis sets. As an application, orthogonal radial wavefunctions of the STO type have been obtained for the 3 d transition metal atoms and ions by simulation of the high-quality sets of Clementi and Roetti. The performance of the reduction has been evaluated by examining several one- and two-electron interactions. Results of these tests reveal that the new functions are highly accurate simulations of the reference AO's. They appear to be appropriate for molecular and solid state calculations.

  17. Studies in the parameterization of cloudiness in climate models and the analysis of radiation fields in general circulation models

    NASA Technical Reports Server (NTRS)

    HARSHVARDHAN

    1990-01-01

    Broad-band parameterizations for atmospheric radiative transfer were developed for clear and cloudy skies. These were in the shortwave and longwave regions of the spectrum. These models were compared with other models in an international effort called ICRCCM (Intercomparison of Radiation Codes for Climate Models). The radiation package developed was used for simulations of a General Circulation Model (GCM). A synopsis is provided of the research accomplishments in the two areas separately. Details are available in the published literature.

  18. AA Fest General Circulation Model Development: Past, Present and Future. A Symposium in Honor of Professor Akio Arakawa

    SciTech Connect

    Ide, Kayo

    1998-01-22

    On January 20-22, 1998, ''AA Fest. A Symposium on General Circulation Model Development: Past, Present, and Future'' was held at the North West Campus Auditorium of University of California, Los Angeles, in honor of Professor Ako Arawaka. The symposium consisted of two-and-a-half-day technical presentations, along with a banquet in the opening evening and a reception during the poster session of the second evening.

  19. The significance of cloud-radiative forcing to the general circulation on climate time scales - A satellite interpretation

    NASA Technical Reports Server (NTRS)

    Sohn, Byung-Ju; Smith, Eric A.

    1992-01-01

    This paper focuses on the role of cloud- and surface-atmosphere forcing on the net radiation balance and their potential impact on the general circulation at climate time scales. The globally averaged cloud-forcing estimates and cloud sensitivity values taken from various recent studies are summarized. It is shown that the net radiative heating over the tropics is principally due to high clouds, while the net cooling in mid- and high latitudes is dominated by low and middle clouds.

  20. 3D steerable wavelets in practice.

    PubMed

    Chenouard, Nicolas; Unser, Michael

    2012-11-01

    We introduce a systematic and practical design for steerable wavelet frames in 3D. Our steerable wavelets are obtained by applying a 3D version of the generalized Riesz transform to a primary isotropic wavelet frame. The novel transform is self-reversible (tight frame) and its elementary constituents (Riesz wavelets) can be efficiently rotated in any 3D direction by forming appropriate linear combinations. Moreover, the basis functions at a given location can be linearly combined to design custom (and adaptive) steerable wavelets. The features of the proposed method are illustrated with the processing and analysis of 3D biomedical data. In particular, we show how those wavelets can be used to characterize directional patterns and to detect edges by means of a 3D monogenic analysis. We also propose a new inverse-problem formalism along with an optimization algorithm for reconstructing 3D images from a sparse set of wavelet-domain edges. The scheme results in high-quality image reconstructions which demonstrate the feature-reduction ability of the steerable wavelets as well as their potential for solving inverse problems.

  1. 3D Viscoelastic traction force microscopy.

    PubMed

    Toyjanova, Jennet; Hannen, Erin; Bar-Kochba, Eyal; Darling, Eric M; Henann, David L; Franck, Christian

    2014-10-28

    Native cell-material interactions occur on materials differing in their structural composition, chemistry, and physical compliance. While the last two decades have shown the importance of traction forces during cell-material interactions, they have been almost exclusively presented on purely elastic in vitro materials. Yet, most bodily tissue materials exhibit some level of viscoelasticity, which could play an important role in how cells sense and transduce tractions. To expand the realm of cell traction measurements and to encompass all materials from elastic to viscoelastic, this paper presents a general, and comprehensive approach for quantifying 3D cell tractions in viscoelastic materials. This methodology includes the experimental characterization of the time-dependent material properties for any viscoelastic material with the subsequent mathematical implementation of the determined material model into a 3D traction force microscopy (3D TFM) framework. Utilizing this new 3D viscoelastic TFM (3D VTFM) approach, we quantify the influence of viscosity on the overall material traction calculations and quantify the error associated with omitting time-dependent material effects, as is the case for all other TFM formulations. We anticipate that the 3D VTFM technique will open up new avenues of cell-material investigations on even more physiologically relevant time-dependent materials including collagen and fibrin gels.

  2. Documentation of a ground hydrology parameterization for use in the GISS atmospheric general circulation model

    NASA Technical Reports Server (NTRS)

    Lin, J. D.; Aleano, J.; Bock, P.

    1978-01-01

    The moisture transport processes related to the earth's surface relevant to the ground circulation model GCM are presented. The GHM parametrizations considered are: (1) ground wetness and soil parameters; (2) precipitation; (3) evapotranspiration; (4) surface storage of snow and ice; and (5) runout. The computational aspects of the GHM using computer programs and flow charts are described.

  3. 3D gaze tracking system for NVidia 3D Vision®.

    PubMed

    Wibirama, Sunu; Hamamoto, Kazuhiko

    2013-01-01

    Inappropriate parallax setting in stereoscopic content generally causes visual fatigue and visual discomfort. To optimize three dimensional (3D) effects in stereoscopic content by taking into account health issue, understanding how user gazes at 3D direction in virtual space is currently an important research topic. In this paper, we report the study of developing a novel 3D gaze tracking system for Nvidia 3D Vision(®) to be used in desktop stereoscopic display. We suggest an optimized geometric method to accurately measure the position of virtual 3D object. Our experimental result shows that the proposed system achieved better accuracy compared to conventional geometric method by average errors 0.83 cm, 0.87 cm, and 1.06 cm in X, Y, and Z dimensions, respectively.

  4. 3D World Building System

    ScienceCinema

    None

    2016-07-12

    This video provides an overview of the Sandia National Laboratories developed 3-D World Model Building capability that provides users with an immersive, texture rich 3-D model of their environment in minutes using a laptop and color and depth camera.

  5. 3D Buckligami: Digital Matter

    NASA Astrophysics Data System (ADS)

    van Hecke, Martin; de Reus, Koen; Florijn, Bastiaan; Coulais, Corentin

    2014-03-01

    We present a class of elastic structures which exhibit collective buckling in 3D, and create these by a 3D printing/moulding technique. Our structures consist of cubic lattice of anisotropic unit cells, and we show that their mechanical properties are programmable via the orientation of these unit cells.

  6. 3D World Building System

    SciTech Connect

    2013-10-30

    This video provides an overview of the Sandia National Laboratories developed 3-D World Model Building capability that provides users with an immersive, texture rich 3-D model of their environment in minutes using a laptop and color and depth camera.

  7. LLNL-Earth3D

    SciTech Connect

    2013-10-01

    Earth3D is a computer code designed to allow fast calculation of seismic rays and travel times through a 3D model of the Earth. LLNL is using this for earthquake location and global tomography efforts and such codes are of great interest to the Earth Science community.

  8. Market study: 3-D eyetracker

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A market study of a proposed version of a 3-D eyetracker for initial use at NASA's Ames Research Center was made. The commercialization potential of a simplified, less expensive 3-D eyetracker was ascertained. Primary focus on present and potential users of eyetrackers, as well as present and potential manufacturers has provided an effective means of analyzing the prospects for commercialization.

  9. 3D vision system assessment

    NASA Astrophysics Data System (ADS)

    Pezzaniti, J. Larry; Edmondson, Richard; Vaden, Justin; Hyatt, Bryan; Chenault, David B.; Kingston, David; Geulen, Vanilynmae; Newell, Scott; Pettijohn, Brad

    2009-02-01

    In this paper, we report on the development of a 3D vision system consisting of a flat panel stereoscopic display and auto-converging stereo camera and an assessment of the system's use for robotic driving, manipulation, and surveillance operations. The 3D vision system was integrated onto a Talon Robot and Operator Control Unit (OCU) such that direct comparisons of the performance of a number of test subjects using 2D and 3D vision systems were possible. A number of representative scenarios were developed to determine which tasks benefited most from the added depth perception and to understand when the 3D vision system hindered understanding of the scene. Two tests were conducted at Fort Leonard Wood, MO with noncommissioned officers ranked Staff Sergeant and Sergeant First Class. The scenarios; the test planning, approach and protocols; the data analysis; and the resulting performance assessment of the 3D vision system are reported.

  10. 3D printing in dentistry.

    PubMed

    Dawood, A; Marti Marti, B; Sauret-Jackson, V; Darwood, A

    2015-12-01

    3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery.

  11. PLOT3D user's manual

    NASA Technical Reports Server (NTRS)

    Walatka, Pamela P.; Buning, Pieter G.; Pierce, Larry; Elson, Patricia A.

    1990-01-01

    PLOT3D is a computer graphics program designed to visualize the grids and solutions of computational fluid dynamics. Seventy-four functions are available. Versions are available for many systems. PLOT3D can handle multiple grids with a million or more grid points, and can produce varieties of model renderings, such as wireframe or flat shaded. Output from PLOT3D can be used in animation programs. The first part of this manual is a tutorial that takes the reader, keystroke by keystroke, through a PLOT3D session. The second part of the manual contains reference chapters, including the helpfile, data file formats, advice on changing PLOT3D, and sample command files.

  12. The general circulation and meridional heat transport of the subtropical South Atlantic determined by inverse methods

    NASA Technical Reports Server (NTRS)

    Fu, L.-L.

    1981-01-01

    The circulation and meridional heat transport of the subtropical South Atlantic Ocean are determined through the application of the inverse method of Wunsch (1978) to hydrographic data from the IGY and METEOR expeditions. Meridional circulation results of the two data sets agree on a northward mass transport of about 20 million metric tons/sec for waters above the North Atlantic Deep Water (NADW), and a comparable southward transport of deep waters. Additional gross features held in common are the Benguela, South Equatorial and North Brazilian Coastal currents' northward transport of the Surface Water, and the deflection of the southward-flowing NADW from the South American Coast into the mid ocean by a seamount chain near 20 deg S. Total heat transport is equatorward, with a magnitude of 0.8 X 10 to the 15th W near 30 deg S and indistinguishable from zero near 8 deg S.

  13. Characterizing the Influence of the General Circulation on Marine Boundary Layer Clouds

    NASA Technical Reports Server (NTRS)

    Rozendaal, Margaret A.; Rossow, William B.; Hansen, James E. (Technical Monitor)

    2001-01-01

    The seasonal and intraseasonal variability of boundary layer cloud in the subtropical eastern oceans are studied using combined data from the International Satellite Cloud Climatology Project (ISCCP) and the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis. Spectral analysis reveals that most of the time variability of cloud properties occurs on seasonal to annual time scales. The variance decreases one to two orders of magnitude for each decade of time scale decrease, indicating that daily to monthly time scales have smaller, but non-negligible variability. The length of these dominant time scales suggests that the majority of the variability is influenced by the general circulation and its interaction with boundary layer turbulence, rather than a product of boundary layer turbulence alone. Previous datasets have lacked the necessary resolution in either time or in space to properly characterize variability on synoptic scales; this is remedied by using global satellite-retrieved cloud properties. We characterize the intraseasonal subtropical cloud variability in both hemispheres and in different seasons. In addition to cloud fraction, we examine variability of cloud optical thickness - cloud top pressure frequency distributions. Despite the large concentration of research on the variability of Northern Hemisphere (NH) regions during summer, it is noted that the largest amplitude intraseasonal variability in the NH regions occurs during local winter. The effect of intraseasonal variability on the calculation and interpretation of seasonal results is investigated. Decreases in seasonally averaged cloud cover, optical thickness and cloud top pressure from the May-through-September season to the November-through-March season are most apparent in the NH regions. Further analysis indicates that these changes are due to an increase in frequency, but a decrease in the persistence of synoptic events. In addition, changes in cloud top pressure and

  14. Temporal and spatial intermittency of sub-daily precipitation in general circulation models

    NASA Astrophysics Data System (ADS)

    Klingaman, Nicholas; Martin, Gill; Moise, Aurel

    2015-04-01

    General circulation models often fail to reproduce the observed spatial and temporal distributions of tropical precipitation (e.g. Stephens et al. 2010). The need for improved understanding of how a warming climate may change precipitation variability and extremes has focused model developers' attention on the inability of convection parameterizations to represent the observed range of deep convective processes (e.g. Rossow et al. 2013). As climate-model resolutions increase towards scales previously used for short-term forecasting, the benefits of seamless modelling are being balanced by increasingly apparent deficiencies in convection parameterizations. Under particular scrutiny are the consequences of poorly simulated sub-daily, gridpoint precipitation variability on rainfall distributions at longer (e.g., daily, seasonal, decadal) and larger scales. We present the behaviour of tropical convection in the MetUM in a hierarchy of global configurations from ~10km to ~100km resolution, and in ten climate models from the "Vertical Structure and Diabatic Processes of the Madden-Julian Oscillation" project. We establish new methods of analysing timestep precipitation that allow comparisons between resolutions and physical parameterizations. We first investigate the relationship between timestep-to-timestep variations of modelled convection at the gridbox scale and its variability on longer and larger scales, and compare simulated and observed rainfall variability. We demonstrate that convection parameterization changes that alter timestep variability (e.g., entrainment and detrainment rates and closure timescales) also affect longer-scale variability. For example, we show that ~100 km configurations exhibit coherent timestep intermittency at large spatial scales, which reduce at finer resolutions and with parameterisation changes that suppress the depth and intensity of convection. Despite a wide variety of timestep behaviour, the models from the "Vertical Structure

  15. Aerosol indirect effects ? general circulation model intercomparison and evaluation with satellite data

    SciTech Connect

    Quaas, Johannes; Ming, Yi; Menon, Surabi; Takemura, Toshihiko; Wang, Minghuai; Penner, Joyce E.; Gettelman, Andrew; Lohmann, Ulrike; Bellouin, Nicolas; Boucher, Olivier; Sayer, Andrew M.; Thomas, Gareth E.; McComiskey, Allison; Feingold, Graham; Hoose, Corinna; Kristansson, Jon Egill; Liu, Xiaohong; Balkanski, Yves; Donner, Leo J.; Ginoux, Paul A.; Stier, Philip; Grandey, Benjamin; Feichter, Johann; Sednev, Igor; Bauer, Susanne E.; Koch, Dorothy; Grainger, Roy G.; Kirkevag, Alf; Iversen, Trond; Seland, Oyvind; Easter, Richard; Ghan, Steven J.; Rasch, Philip J.; Morrison, Hugh; Lamarque, Jean-Francois; Iacono, Michael J.; Kinne, Stefan; Schulz, Michael

    2010-03-12

    Aerosol indirect effects continue to constitute one of the most important uncertainties for anthropogenic climate perturbations. Within the international AEROCOM initiative, the representation of aerosol-cloud-radiation interactions in ten different general circulation models (GCMs) is evaluated using three satellite datasets. The focus is on stratiform liquid water clouds since most GCMs do not include ice nucleation effects, and none of the model explicitly parameterises aerosol effects on convective clouds. We compute statistical relationships between aerosol optical depth ({tau}{sub a}) and various cloud and radiation quantities in a manner that is consistent between the models and the satellite data. It is found that the model-simulated influence of aerosols on cloud droplet number concentration (N{sub d}) compares relatively well to the satellite data at least over the ocean. The relationship between {tau}{sub a} and liquid water path is simulated much too strongly by the models. This suggests that the implementation of the second aerosol indirect effect mainly in terms of an autoconversion parameterisation has to be revisited in the GCMs. A positive relationship between total cloud fraction (f{sub cld}) and {tau}{sub a} as found in the satellite data is simulated by the majority of the models, albeit less strongly than that in the satellite data in most of them. In a discussion of the hypotheses proposed in the literature to explain the satellite-derived strong f{sub cld} - {tau}{sub a} relationship, our results indicate that none can be identified as a unique explanation. Relationships similar to the ones found in satellite data between {tau}{sub a} and cloud top temperature or outgoing long-wave radiation (OLR) are simulated by only a few GCMs. The GCMs that simulate a negative OLR - {tau}{sub a} relationship show a strong positive correlation between {tau}{sub a} and f{sub cld} The short-wave total aerosol radiative forcing as simulated by the GCMs is

  16. Impacts of sudden stratospheric warming on general circulation of the thermosphere

    NASA Astrophysics Data System (ADS)

    Miyoshi, Yasunobu; Fujiwara, Hitoshi; Jin, Hidekatsu; Shinagawa, Hiroyuki

    2015-12-01

    Impacts of sudden stratospheric warming (SSW) on the thermosphere were studied using a gravity wave (GW)-resolving whole atmosphere model. During an SSW event, the mesosphere at high latitudes cools, and the lower thermosphere becomes warm. At the peak of the SSW event, a temperature drop occurs above an altitude of 150 km at high latitudes. Our results indicate that the SSW event strongly affects meridional circulation and GW drag in the thermosphere. In the lower thermosphere, upward wind in the Arctic region, southward wind in the region between the North Pole and the South Pole, and downward wind in the Antarctic region are dominant before SSW occurs. The SSW event reverses meridional circulation at altitudes between 90 and 125 km in the Northern Hemisphere. During the SSW event, downward wind in the Arctic region and northward wind in the Northern Hemisphere prevail in the lower thermosphere. A detailed analysis revealed that during the SSW event, the change in meridional circulation is caused by the attenuation of the GW drag, and we identified the mechanism responsible for this attenuation. Moreover, we assessed the impacts of SSW on temperatures in the equatorial region and Southern Hemisphere.

  17. Unassisted 3D camera calibration

    NASA Astrophysics Data System (ADS)

    Atanassov, Kalin; Ramachandra, Vikas; Nash, James; Goma, Sergio R.

    2012-03-01

    With the rapid growth of 3D technology, 3D image capture has become a critical part of the 3D feature set on mobile phones. 3D image quality is affected by the scene geometry as well as on-the-device processing. An automatic 3D system usually assumes known camera poses accomplished by factory calibration using a special chart. In real life settings, pose parameters estimated by factory calibration can be negatively impacted by movements of the lens barrel due to shaking, focusing, or camera drop. If any of these factors displaces the optical axes of either or both cameras, vertical disparity might exceed the maximum tolerable margin and the 3D user may experience eye strain or headaches. To make 3D capture more practical, one needs to consider unassisted (on arbitrary scenes) calibration. In this paper, we propose an algorithm that relies on detection and matching of keypoints between left and right images. Frames containing erroneous matches, along with frames with insufficiently rich keypoint constellations, are detected and discarded. Roll, pitch yaw , and scale differences between left and right frames are then estimated. The algorithm performance is evaluated in terms of the remaining vertical disparity as compared to the maximum tolerable vertical disparity.

  18. Simulating pathways of subsurface oil in the Faroe-Shetland Channel using an ocean general circulation model.

    PubMed

    Main, C E; Yool, A; Holliday, N P; Popova, E E; Jones, D O B; Ruhl, H A

    2017-01-15

    Little is known about the fate of subsurface hydrocarbon plumes from deep-sea oil well blowouts and their effects on processes and communities. As deepwater drilling expands in the Faroe-Shetland Channel (FSC), oil well blowouts are a possibility, and the unusual ocean circulation of this region presents challenges to understanding possible subsurface oil pathways in the event of a spill. Here, an ocean general circulation model was used with a particle tracking algorithm to assess temporal variability of the oil-plume distribution from a deep-sea oil well blowout in the FSC. The drift of particles was first tracked for one year following release. Then, ambient model temperatures were used to simulate temperature-mediated biodegradation, truncating the trajectories of particles accordingly. Release depth of the modeled subsurface plumes affected both their direction of transport and distance travelled from their release location, and there was considerable interannual variability in transport.

  19. Stable isotopes of fossil teeth corroborate key general circulation model predictions for the Last Glacial Maximum in North America

    NASA Astrophysics Data System (ADS)

    Kohn, Matthew J.; McKay, Moriah

    2010-11-01

    Oxygen isotope data provide a key test of general circulation models (GCMs) for the Last Glacial Maximum (LGM) in North America, which have otherwise proved difficult to validate. High δ18O pedogenic carbonates in central Wyoming have been interpreted to indicate increased summer precipitation sourced from the Gulf of Mexico. Here we show that tooth enamel δ18O of large mammals, which is strongly correlated with local water and precipitation δ18O, is lower during the LGM in Wyoming, not higher. Similar data from Texas, California, Florida and Arizona indicate higher δ18O values than in the Holocene, which is also predicted by GCMs. Tooth enamel data closely validate some recent models of atmospheric circulation and precipitation δ18O, including an increase in the proportion of winter precipitation for central North America, and summer precipitation in the southern US, but suggest aridity can bias pedogenic carbonate δ18O values significantly.

  20. 3D Scan Systems Integration

    DTIC Science & Technology

    2007-11-02

    AGENCY USE ONLY (Leave Blank) 2. REPORT DATE 5 Feb 98 4. TITLE AND SUBTITLE 3D Scan Systems Integration REPORT TYPE AND DATES COVERED...2-89) Prescribed by ANSI Std. Z39-1 298-102 [ EDO QUALITY W3PECTEDI DLA-ARN Final Report for US Defense Logistics Agency on DDFG-T2/P3: 3D...SCAN SYSTEMS INTEGRATION Contract Number SPO100-95-D-1014 Contractor Ohio University Delivery Order # 0001 Delivery Order Title 3D Scan Systems

  1. Self assembled structures for 3D integration

    NASA Astrophysics Data System (ADS)

    Rao, Madhav

    Three dimensional (3D) micro-scale structures attached to a silicon substrate have various applications in microelectronics. However, formation of 3D structures using conventional micro-fabrication techniques are not efficient and require precise control of processing parameters. Self assembly is a method for creating 3D structures that takes advantage of surface area minimization phenomena. Solder based self assembly (SBSA), the subject of this dissertation, uses solder as a facilitator in the formation of 3D structures from 2D patterns. Etching a sacrificial layer underneath a portion of the 2D pattern allows the solder reflow step to pull those areas out of the substrate plane resulting in a folded 3D structure. Initial studies using the SBSA method demonstrated low yields in the formation of five different polyhedra. The failures in folding were primarily attributed to nonuniform solder deposition on the underlying metal pads. The dip soldering method was analyzed and subsequently refined. A modified dip soldering process provided improved yield among the polyhedra. Solder bridging referred as joining of solder deposited on different metal patterns in an entity influenced the folding mechanism. In general, design parameters such as small gap-spacings and thick metal pads were found to favor solder bridging for all patterns studied. Two types of soldering: face and edge soldering were analyzed. Face soldering refers to the application of solder on the entire metal face. Edge soldering indicates application of solder only on the edges of the metal face. Mechanical grinding showed that face soldered SBSA structures were void free and robust in nature. In addition, the face soldered 3D structures provide a consistent heat resistant solder standoff height that serve as attachments in the integration of dissimilar electronic technologies. Face soldered 3D structures were developed on the underlying conducting channel to determine the thermo-electric reliability of

  2. PLOT3D Export Tool for Tecplot

    NASA Technical Reports Server (NTRS)

    Alter, Stephen

    2010-01-01

    The PLOT3D export tool for Tecplot solves the problem of modified data being impossible to output for use by another computational science solver. The PLOT3D Exporter add-on enables the use of the most commonly available visualization tools to engineers for output of a standard format. The exportation of PLOT3D data from Tecplot has far reaching effects because it allows for grid and solution manipulation within a graphical user interface (GUI) that is easily customized with macro language-based and user-developed GUIs. The add-on also enables the use of Tecplot as an interpolation tool for solution conversion between different grids of different types. This one add-on enhances the functionality of Tecplot so significantly, it offers the ability to incorporate Tecplot into a general suite of tools for computational science applications as a 3D graphics engine for visualization of all data. Within the PLOT3D Export Add-on are several functions that enhance the operations and effectiveness of the add-on. Unlike Tecplot output functions, the PLOT3D Export Add-on enables the use of the zone selection dialog in Tecplot to choose which zones are to be written by offering three distinct options - output of active, inactive, or all zones (grid blocks). As the user modifies the zones to output with the zone selection dialog, the zones to be written are similarly updated. This enables the use of Tecplot to create multiple configurations of a geometry being analyzed. For example, if an aircraft is loaded with multiple deflections of flaps, by activating and deactivating different zones for a specific flap setting, new specific configurations of that aircraft can be easily generated by only writing out specific zones. Thus, if ten flap settings are loaded into Tecplot, the PLOT3D Export software can output ten different configurations, one for each flap setting.

  3. 3-D Mesh Generation Nonlinear Systems

    SciTech Connect

    Christon, M. A.; Dovey, D.; Stillman, D. W.; Hallquist, J. O.; Rainsberger, R. B

    1994-04-07

    INGRID is a general-purpose, three-dimensional mesh generator developed for use with finite element, nonlinear, structural dynamics codes. INGRID generates the large and complex input data files for DYNA3D, NIKE3D, FACET, and TOPAZ3D. One of the greatest advantages of INGRID is that virtually any shape can be described without resorting to wedge elements, tetrahedrons, triangular elements or highly distorted quadrilateral or hexahedral elements. Other capabilities available are in the areas of geometry and graphics. Exact surface equations and surface intersections considerably improve the ability to deal with accurate models, and a hidden line graphics algorithm is included which is efficient on the most complicated meshes. The primary new capability is associated with the boundary conditions, loads, and material properties required by nonlinear mechanics programs. Commands have been designed for each case to minimize user effort. This is particularly important since special processing is almost always required for each load or boundary condition.

  4. 3D polymer scaffold arrays.

    PubMed

    Simon, Carl G; Yang, Yanyin; Dorsey, Shauna M; Ramalingam, Murugan; Chatterjee, Kaushik

    2011-01-01

    We have developed a combinatorial platform for fabricating tissue scaffold arrays that can be used for screening cell-material interactions. Traditional research involves preparing samples one at a time for characterization and testing. Combinatorial and high-throughput (CHT) methods lower the cost of research by reducing the amount of time and material required for experiments by combining many samples into miniaturized specimens. In order to help accelerate biomaterials research, many new CHT methods have been developed for screening cell-material interactions where materials are presented to cells as a 2D film or surface. However, biomaterials are frequently used to fabricate 3D scaffolds, cells exist in vivo in a 3D environment and cells cultured in a 3D environment in vitro typically behave more physiologically than those cultured on a 2D surface. Thus, we have developed a platform for fabricating tissue scaffold libraries where biomaterials can be presented to cells in a 3D format.

  5. Combinatorial 3D Mechanical Metamaterials

    NASA Astrophysics Data System (ADS)

    Coulais, Corentin; Teomy, Eial; de Reus, Koen; Shokef, Yair; van Hecke, Martin

    2015-03-01

    We present a class of elastic structures which exhibit 3D-folding motion. Our structures consist of cubic lattices of anisotropic unit cells that can be tiled in a complex combinatorial fashion. We design and 3d-print this complex ordered mechanism, in which we combine elastic hinges and defects to tailor the mechanics of the material. Finally, we use this large design space to encode smart functionalities such as surface patterning and multistability.

  6. A Coupled Ocean General Circulation, Biogeochemical, and Radiative Model of the Global Oceans: Seasonal Distributions of Ocean Chlorophyll and Nutrients

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.; Busalacchi, Antonio (Technical Monitor)

    2000-01-01

    A coupled ocean general circulation, biogeochemical, and radiative model was constructed to evaluate and understand the nature of seasonal variability of chlorophyll and nutrients in the global oceans. Biogeochemical processes in the model are determined from the influences of circulation and turbulence dynamics, irradiance availability. and the interactions among three functional phytoplankton groups (diatoms. chlorophytes, and picoplankton) and three nutrients (nitrate, ammonium, and silicate). Basin scale (greater than 1000 km) model chlorophyll results are in overall agreement with CZCS pigments in many global regions. Seasonal variability observed in the CZCS is also represented in the model. Synoptic scale (100-1000 km) comparisons of imagery are generally in conformance although occasional departures are apparent. Model nitrate distributions agree with in situ data, including seasonal dynamics, except for the equatorial Atlantic. The overall agreement of the model with satellite and in situ data sources indicates that the model dynamics offer a reasonably realistic simulation of phytoplankton and nutrient dynamics on synoptic scales. This is especially true given that initial conditions are homogenous chlorophyll fields. The success of the model in producing a reasonable representation of chlorophyll and nutrient distributions and seasonal variability in the global oceans is attributed to the application of a generalized, processes-driven approach as opposed to regional parameterization and the existence of multiple phytoplankton groups with different physiological and physical properties. These factors enable the model to simultaneously represent many aspects of the great diversity of physical, biological, chemical, and radiative environments encountered in the global oceans.

  7. The global geochemistry of bomb-produced tritium - General circulation model compared to available observations and traditional interpretations

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Broecker, Wallace S.; Jouzel, Jean; Suozzo, Robert J.; Russell, Gary L.; Rind, David

    1989-01-01

    Observational evidence suggests that of the tritium produced during nuclear bomb tests that has already reached the ocean, more than twice as much arrived through vapor impact as through precipitation. In the present study, the Goddard Institute for Space Studies 8 x 10 deg atmospheric general circulation model is used to simulate tritium transport from the upper atmosphere to the ocean. The simulation indicates that tritium delivery to the ocean via vapor impact is about equal to that via precipitation. The model result is relatively insensitive to several imposed changes in tritium source location, in model parameterizations, and in model resolution. Possible reasons for the discrepancy are explored.

  8. Seasonal Water Transport in the Atmosphere of Mars: Applications of a Mars General Circulation Model Using Mars Global Surveyor Data

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1999-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. We present below a summary of progress made during the duration of this JRI. The focus of this JRI has been to investigate seasonal water vapor transport in the atmosphere of Mars and its effects on the planet's present climate. To this end, the primary task has been to adapt a new dynamical processor for the adiabatic tendencies of the atmospheric circulation into the NASA Ames Mars general circulation model (MGCM). Using identical boundary and initial conditions, several comparative tests between the new and old MGCMs have been performed and the nature of the simulated circulations have been diagnosed. With confidence that the updated version of the Ames MGCM produces quite similar mean and eddy circulation statistics, the new climate model is well poised as a tool to pursue fundamental questions related to the spatial and seasonal variations of atmospheric water vapor on Mars, and to explore exchanges of water with non-atmospheric reservoirs and transport within its atmosphere. In particular, the role of surface sources and sinks can be explored, the range of water-vapor saturation altitudes can be investigated, and plausible precipitation mechanisms can be studied, for a range of atmospheric dust loadings, such future investigations can contribute to a comprehensive study of surface inventories, exchange mechanisms, and the relative importance of atmospheric transport Mars' water cycle. A listing of presentations made and manuscripts submitted during the course of this project is provided.

  9. Seasonal Water Transport in the Atmosphere of Mars: Applications of a Mars General Circulation Model Using Mars Global Surveyor Data

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1999-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. We present below a summary of progress made during the duration of this JRI. The focus of this JRI has been to investigate seasonal water vapor transport in the atmosphere of Mars and its effects on the planet's present climate. To this end, the primary task has been to adapt a new dynamical processor for the adiabatic tendencies of the atmospheric circulation into the NASA Ames Mars general circulation model (MGCM). Using identical boundary and initial conditions, several comparative tests between the new and old MGCMs have been performed and the nature of the simulated circulations have been diagnosed. With confidence that the updated version of the Ames MGCM produces quite similar mean and eddy circulation statistics, the new climate model is well poised as a tool to pursue fundamental questions related to the spatial and seasonal variations of atmospheric water vapor on Mars, and to explore exchanges of water with non-atmospheric reservoirs and transport within its atmosphere. In particular, the role of surface sources and sinks can be explored, the range of water-vapor saturation altitudes can be investigated, and plausible precipitation mechanisms can be studied, for a range of atmospheric dust loadings. Such future investigations can contribute to a comprehensive study of surface inventories, exchange mechanisms, and the relative importance of atmospheric transport Mars' water cycle. A listing of presentations made and manuscripts submitted during the course of this project is provided.

  10. From 3D view to 3D print

    NASA Astrophysics Data System (ADS)

    Dima, M.; Farisato, G.; Bergomi, M.; Viotto, V.; Magrin, D.; Greggio, D.; Farinato, J.; Marafatto, L.; Ragazzoni, R.; Piazza, D.

    2014-08-01

    In the last few years 3D printing is getting more and more popular and used in many fields going from manufacturing to industrial design, architecture, medical support and aerospace. 3D printing is an evolution of bi-dimensional printing, which allows to obtain a solid object from a 3D model, realized with a 3D modelling software. The final product is obtained using an additive process, in which successive layers of material are laid down one over the other. A 3D printer allows to realize, in a simple way, very complex shapes, which would be quite difficult to be produced with dedicated conventional facilities. Thanks to the fact that the 3D printing is obtained superposing one layer to the others, it doesn't need any particular work flow and it is sufficient to simply draw the model and send it to print. Many different kinds of 3D printers exist based on the technology and material used for layer deposition. A common material used by the toner is ABS plastics, which is a light and rigid thermoplastic polymer, whose peculiar mechanical properties make it diffusely used in several fields, like pipes production and cars interiors manufacturing. I used this technology to create a 1:1 scale model of the telescope which is the hardware core of the space small mission CHEOPS (CHaracterising ExOPlanets Satellite) by ESA, which aims to characterize EXOplanets via transits observations. The telescope has a Ritchey-Chrétien configuration with a 30cm aperture and the launch is foreseen in 2017. In this paper, I present the different phases for the realization of such a model, focusing onto pros and cons of this kind of technology. For example, because of the finite printable volume (10×10×12 inches in the x, y and z directions respectively), it has been necessary to split the largest parts of the instrument in smaller components to be then reassembled and post-processed. A further issue is the resolution of the printed material, which is expressed in terms of layers

  11. A Nonlinear Multigrid Solver for an Atmospheric General Circulation Model Based on Semi-Implicit Semi-Lagrangian Advection of Potential Vorticity

    NASA Technical Reports Server (NTRS)

    McCormick, S.; Ruge, John W.

    1998-01-01

    This work represents a part of a project to develop an atmospheric general circulation model based on the semi-Lagrangian advection of potential vorticity (PC) with divergence as the companion prognostic variable.

  12. Preformed and regenerated phosphate in ocean general circulation models: can right total concentrations be wrong?

    NASA Astrophysics Data System (ADS)

    Duteil, O.; Koeve, W.; Oschlies, A.; Aumont, O.; Bianchi, D.; Bopp, L.; Galbraith, E.; Matear, R.; Moore, J. K.; Sarmiento, J. L.; Segschneider, J.

    2012-05-01

    Phosphate distributions simulated by seven state-of-the-art biogeochemical ocean circulation models are evaluated against observations of global ocean nutrient distributions. The biogeochemical models exhibit different structural complexities, ranging from simple nutrient-restoring to multi-nutrient NPZD type models. We evaluate the simulations using the observed volume distribution of phosphate. The errors in these simulated volume class distributions are significantly larger when preformed phosphate (or regenerated phosphate) rather than total phosphate is considered. Our analysis reveals that models can achieve similarly good fits to observed total phosphate distributions for a~very different partitioning into preformed and regenerated nutrient components. This has implications for the strength and potential climate sensitivity of the simulated biological carbon pump. We suggest complementing the use of total nutrient distributions for assessing model skill by an evaluation of the respective preformed and regenerated nutrient components.

  13. Preformed and regenerated phosphate in ocean general circulation models: can right total concentrations be wrong?

    NASA Astrophysics Data System (ADS)

    Duteil, O.; Koeve, W.; Oschlies, A.; Aumont, O.; Bianchi, D.; Bopp, L.; Galbraith, E.; Matear, R.; Moore, J. K.; Sarmiento, J. L.; Segschneider, J.

    2011-12-01

    Phosphate distributions simulated by seven state-of-the-art biogeochemical ocean circulation models are evaluated against observations of global ocean nutrient distributions. The biogeochemical models exhibit different structural complexities, ranging from simple nutrient-restoring to multi-nutrient NPZD type models. We evaluate the simulations using the observed volume distribution of phosphate. The errors in these simulated volume class distributions are significantly larger when preformed phosphate (or regenerated phosphate) rather than total phosphate is considered. Our analysis reveals that models can achieve similarly good fits to observed total phosphate distributions for a very different partitioning into preformed and regenerated nutrient components. This has implications for the strength and potential climate sensitivity of the simulated biological carbon pump. We suggest complementing the use of total nutrient distributions for assessing model skill by an evaluation of the respective preformed and regenerated nutrient components.

  14. Analysis of general circulation model results and comparison with regional climatic data, Task 3. [Progress report

    SciTech Connect

    Cess, R.D.; Hameed, S.

    1989-12-31

    On time scales of greater than one year the variability of weather and climate on a large path of the Earth is dominated by the Southern Oscillation. While current theories of this phenomenon have clarified the role of the interaction between the ocean and the atmosphere in maintaining this oscillation it has so far been unclear whether the Southern Oscillation originates in the ocean, in the atmosphere or during the interaction between the ocean and the atmosphere. In this study we compared simulations of climate in two global circulation models: the coupled OSU GCM in which the atmosphere and ocean interact dynamically and the slab OSU GCM in which the ocean is represented by a static layer.

  15. Analysis of general circulation model results and comparison with regional climatic data, Task 3

    SciTech Connect

    Cess, R.D.; Hameed, S.

    1989-01-01

    On time scales of greater than one year the variability of weather and climate on a large path of the Earth is dominated by the Southern Oscillation. While current theories of this phenomenon have clarified the role of the interaction between the ocean and the atmosphere in maintaining this oscillation it has so far been unclear whether the Southern Oscillation originates in the ocean, in the atmosphere or during the interaction between the ocean and the atmosphere. In this study we compared simulations of climate in two global circulation models: the coupled OSU GCM in which the atmosphere and ocean interact dynamically and the slab OSU GCM in which the ocean is represented by a static layer.

  16. Tests of a new cloud treatment in an atmospheric general circulation model

    SciTech Connect

    Kristjansson, J.E.

    1993-12-08

    In this study we present a new cloud treatment in an atmospheric climate model. The water (or ice) content of clouds is a introduced as a prognostic variable, subject to both advective and diffusive transport. In the first phase of the study, the cloud water does not affect the radiative properties of clouds. We then find differences in precipitation and cloud fields, but little effect on the overall climate. In the second phase the cloud water determines the reflectivity of the clouds. This causes large changes in the global circulation, largely due to enhanced reflection from high tropical cirrus clouds. As a third step, the cloud emissivity is also based on the cloud water content. This greatly enhances the outgoing terrestrial radiation and brings the model`s radiative budget quite close to the observed.

  17. Correction of Excessive Precipitation Over Steep and High Mountains in a General Circulation Model

    NASA Technical Reports Server (NTRS)

    Chao, Winston C.

    2012-01-01

    Excessive precipitation over steep and high mountains (EPSM) is a well-known problem in GCMs and meso-scale models. This problem impairs simulation and data assimilation products. Among the possible causes investigated in this study, we found that the most important one, by far, is a missing upward transport of heat out of the boundary layer due to the vertical circulations forced by the daytime upslope winds, which are forced by the heated boundary layer on subgrid-scale slopes. These upslope winds are associated with large subgrid-scale topographic variation, which is found over steep and high mountains. Without such subgridscale heat ventilation, the resolvable-scale upslope flow in the boundary layer generated by surface sensible heat flux along the mountain slopes is excessive. Such an excessive resolvablescale upslope flow combined with the high moisture content in the boundary layer results in excessive moisture transport toward mountaintops, which in turn gives rise to EPSM. Other possible causes of EPSM that we have investigated include 1) a poorly-designed horizontal moisture flux in the terrain-following coordinates, 2) the condition for cumulus convection being too easily satisfied at mountaintops, 3) the presence of conditional instability of the computational kind, and 4) the absence of blocked flow drag. These are all minor or inconsequential. We have parameterized the ventilation effects of the subgrid-scale heated-slope-induced vertical circulation (SHVC) by removing heat from the boundary layer and depositing it in layers higher up when the topographic variance exceeds a critical value. Test results using NASA/Goddard's GEOS-S GCM have shown that this largely solved the EPSM problem.

  18. YouDash3D: exploring stereoscopic 3D gaming for 3D movie theaters

    NASA Astrophysics Data System (ADS)

    Schild, Jonas; Seele, Sven; Masuch, Maic

    2012-03-01

    Along with the success of the digitally revived stereoscopic cinema, events beyond 3D movies become attractive for movie theater operators, i.e. interactive 3D games. In this paper, we present a case that explores possible challenges and solutions for interactive 3D games to be played by a movie theater audience. We analyze the setting and showcase current issues related to lighting and interaction. Our second focus is to provide gameplay mechanics that make special use of stereoscopy, especially depth-based game design. Based on these results, we present YouDash3D, a game prototype that explores public stereoscopic gameplay in a reduced kiosk setup. It features live 3D HD video stream of a professional stereo camera rig rendered in a real-time game scene. We use the effect to place the stereoscopic effigies of players into the digital game. The game showcases how stereoscopic vision can provide for a novel depth-based game mechanic. Projected trigger zones and distributed clusters of the audience video allow for easy adaptation to larger audiences and 3D movie theater gaming.

  19. OREGANO_VE: a new parallelised 3D solver for the general (non-)linear Maxwell visco-elastic problem: validation and application to the calculation of surface deformation in the earthquake cycle

    NASA Astrophysics Data System (ADS)

    Yamasaki, Tadashi; Houseman, Gregory; Hamling, Ian; Postek, Elek

    2010-05-01

    We have developed a new parallelized 3-D numerical code, OREGANO_VE, for the solution of the general visco-elastic problem in a rectangular block domain. The mechanical equilibrium equation is solved using the finite element method for a (non-)linear Maxwell visco-elastic rheology. Time-dependent displacement and/or traction boundary conditions can be applied. Matrix assembly is based on a tetrahedral element defined by 4 vertex nodes and 6 nodes located at the midpoints of the edges, and within which displacement is described by a quadratic interpolation function. For evaluating viscoelastic relaxation, an explicit time-stepping algorithm (Zienkiewicz and Cormeau, Int. J. Num. Meth. Eng., 8, 821-845, 1974) is employed. We test the accurate implementation of the OREGANO_VE by comparing numerical and analytic (or semi-analytic half-space) solutions to different problems in a range of applications: (1) equilibration of stress in a constant density layer after gravity is switched on at t = 0 tests the implementation of spatially variable viscosity and non-Newtonian viscosity; (2) displacement of the welded interface between two blocks of differing viscosity tests the implementation of viscosity discontinuities, (3) displacement of the upper surface of a layer under applied normal load tests the implementation of time-dependent surface tractions (4) visco-elastic response to dyke intrusion (compared with the solution in a half-space) tests the implementation of all aspects. In each case, the accuracy of the code is validated subject to use of a sufficiently small time step, providing assurance that the OREGANO_VE code can be applied to a range of visco-elastic relaxation processes in three dimensions, including post-seismic deformation and post-glacial uplift. The OREGANO_VE code includes a capability for representation of prescribed fault slip on an internal fault. The surface displacement associated with large earthquakes can be detected by some geodetic observations

  20. Speaking Volumes About 3-D

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In 1999, Genex submitted a proposal to Stennis Space Center for a volumetric 3-D display technique that would provide multiple users with a 360-degree perspective to simultaneously view and analyze 3-D data. The futuristic capabilities of the VolumeViewer(R) have offered tremendous benefits to commercial users in the fields of medicine and surgery, air traffic control, pilot training and education, computer-aided design/computer-aided manufacturing, and military/battlefield management. The technology has also helped NASA to better analyze and assess the various data collected by its satellite and spacecraft sensors. Genex capitalized on its success with Stennis by introducing two separate products to the commercial market that incorporate key elements of the 3-D display technology designed under an SBIR contract. The company Rainbow 3D(R) imaging camera is a novel, three-dimensional surface profile measurement system that can obtain a full-frame 3-D image in less than 1 second. The third product is the 360-degree OmniEye(R) video system. Ideal for intrusion detection, surveillance, and situation management, this unique camera system offers a continuous, panoramic view of a scene in real time.

  1. Approaches of comparison for clear-sky radiative fluxes from general circulation models with Earth Radiation Budget Experiment data

    NASA Technical Reports Server (NTRS)

    Zhang, M. H.; Cess, R. D.; Kwon, T. Y.; Chen, M. H.

    1994-01-01

    In order to compare the clear-sky greenhouse effect and cloud-radiative forcing from general circulation models with Earth Radiation Budget Experiments (ERBE) data, it is necessary to calculate the general circulation model (GCM) clear-sky radiative fluxes in a way consistent with ERBE. This study discusses problems associated with the available methods for clear-sky radiative flux computations in GCMs and proposes a new approach, which uses a statistical relationship between the grid cloud cover and the availability of ERBE clear-sky measurement, established from ERBE pixel data, to sample the model radiative fluxes. Calculations with version 2 of the National Center for Atmospheric Research (NCAR) Community Climate Model using observed sea surface temperature (SST) show good agreement of clear-sky sampling from the proposed method with ERBE sampling. It is also shown that large improvements are achieved in the spatial variability of the model clear-sky radiative fluxes over ocean, with reference to ERBE, by using the new clear-sky sampling method.

  2. The global distribution of natural tritium in precipitation simulated with an Atmospheric General Circulation Model and comparison with observations

    NASA Astrophysics Data System (ADS)

    Cauquoin, A.; Jean-Baptiste, P.; Risi, C.; Fourré, É.; Stenni, B.; Landais, A.

    2015-10-01

    The description of the hydrological cycle in Atmospheric General Circulation Models (GCMs) can be validated using water isotopes as tracers. Many GCMs now simulate the movement of the stable isotopes of water, but here we present the first GCM simulations modelling the content of natural tritium in water. These simulations were obtained using a version of the LMDZ General Circulation Model enhanced by water isotopes diagnostics, LMDZ-iso. To avoid tritium generated by nuclear bomb testing, the simulations have been evaluated against a compilation of published tritium datasets dating from before 1950, or measured recently. LMDZ-iso correctly captures the observed tritium enrichment in precipitation as oceanic air moves inland (the so-called continental effect) and the observed north-south variations due to the latitudinal dependency of the cosmogenic tritium production rate. The seasonal variability, linked to the stratospheric intrusions of air masses with higher tritium content into the troposphere, is correctly reproduced for Antarctica with a maximum in winter. LMDZ-iso reproduces the spring maximum of tritium over Europe, but underestimates it and produces a peak in winter that is not apparent in the data. This implementation of tritium in a GCM promises to provide a better constraint on: (1) the intrusions and transport of air masses from the stratosphere, and (2) the dynamics of the modelled water cycle. The method complements the existing approach of using stable water isotopes.

  3. Approaches of comparison for clear-sky radiative fluxes from general circulation models with earth radiation budget experiment data

    SciTech Connect

    Zhang, M.H.; Cess, R.D.; Kwon, T.Y.; Chen, M.H.

    1994-03-20

    In order to compare the clear-sky greenhouse effect and cloud-radiative forcing from general circulation models with Earth Radiation Budget Experiments (ERBE) data, it is necessary to calculate the general circulation model (GCM) clear-sky radiative fluxes in a way consistent with ERBE. This study discusses problems associated with the available methods for clear-sky radiative flux computations in GCMs and proposes a new approach, which uses a statistical relationship between the grid cloud cover and the availability of ERBE clear-sky measurement, established from ERBE pixel data, to sample the model radiative fluxes. Calculations with version 2 of the NCAR Community Climate Model using observed SST show good agreement of clear-sky sampling from the proposed method with ERBE sampling. It is also shown that large improvements are achieved in the spatial variability of the model clear-sky radiative fluxes over ocean, with reference to ERBE, by using the new clear-sky sampling method. 11 refs., 10 figs.

  4. Macrophage podosomes go 3D.

    PubMed

    Van Goethem, Emeline; Guiet, Romain; Balor, Stéphanie; Charrière, Guillaume M; Poincloux, Renaud; Labrousse, Arnaud; Maridonneau-Parini, Isabelle; Le Cabec, Véronique

    2011-01-01

    Macrophage tissue infiltration is a critical step in the immune response against microorganisms and is also associated with disease progression in chronic inflammation and cancer. Macrophages are constitutively equipped with specialized structures called podosomes dedicated to extracellular matrix (ECM) degradation. We recently reported that these structures play a critical role in trans-matrix mesenchymal migration mode, a protease-dependent mechanism. Podosome molecular components and their ECM-degrading activity have been extensively studied in two dimensions (2D), but yet very little is known about their fate in three-dimensional (3D) environments. Therefore, localization of podosome markers and proteolytic activity were carefully examined in human macrophages performing mesenchymal migration. Using our gelled collagen I 3D matrix model to obligate human macrophages to perform mesenchymal migration, classical podosome markers including talin, paxillin, vinculin, gelsolin, cortactin were found to accumulate at the tip of F-actin-rich cell protrusions together with β1 integrin and CD44 but not β2 integrin. Macrophage proteolytic activity was observed at podosome-like protrusion sites using confocal fluorescence microscopy and electron microscopy. The formation of migration tunnels by macrophages inside the matrix was accomplished by degradation, engulfment and mechanic compaction of the matrix. In addition, videomicroscopy revealed that 3D F-actin-rich protrusions of migrating macrophages were as dynamic as their 2D counterparts. Overall, the specifications of 3D podosomes resembled those of 2D podosome rosettes rather than those of individual podosomes. This observation was further supported by the aspect of 3D podosomes in fibroblasts expressing Hck, a master regulator of podosome rosettes in macrophages. In conclusion, human macrophage podosomes go 3D and take the shape of spherical podosome rosettes when the cells perform mesenchymal migration. This work

  5. 3D Printed Bionic Nanodevices.

    PubMed

    Kong, Yong Lin; Gupta, Maneesh K; Johnson, Blake N; McAlpine, Michael C

    2016-06-01

    The ability to three-dimensionally interweave biological and functional materials could enable the creation of bionic devices possessing unique and compelling geometries, properties, and functionalities. Indeed, interfacing high performance active devices with biology could impact a variety of fields, including regenerative bioelectronic medicines, smart prosthetics, medical robotics, and human-machine interfaces. Biology, from the molecular scale of DNA and proteins, to the macroscopic scale of tissues and organs, is three-dimensional, often soft and stretchable, and temperature sensitive. This renders most biological platforms incompatible with the fabrication and materials processing methods that have been developed and optimized for functional electronics, which are typically planar, rigid and brittle. A number of strategies have been developed to overcome these dichotomies. One particularly novel approach is the use of extrusion-based multi-material 3D printing, which is an additive manufacturing technology that offers a freeform fabrication strategy. This approach addresses the dichotomies presented above by (1) using 3D printing and imaging for customized, hierarchical, and interwoven device architectures; (2) employing nanotechnology as an enabling route for introducing high performance materials, with the potential for exhibiting properties not found in the bulk; and (3) 3D printing a range of soft and nanoscale materials to enable the integration of a diverse palette of high quality functional nanomaterials with biology. Further, 3D printing is a multi-scale platform, allowing for the incorporation of functional nanoscale inks, the printing of microscale features, and ultimately the creation of macroscale devices. This blending of 3D printing, novel nanomaterial properties, and 'living' platforms may enable next-generation bionic systems. In this review, we highlight this synergistic integration of the unique properties of nanomaterials with the

  6. PLOT3D/AMES, DEC VAX VMS VERSION USING DISSPLA (WITH TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. The VAX/VMS/DISSPLA implementation of PLOT3D supports 2-D polygons as

  7. PLOT3D/AMES, DEC VAX VMS VERSION USING DISSPLA (WITHOUT TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P. G.

    1994-01-01

    five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. The VAX/VMS/DISSPLA implementation of PLOT3D supports 2-D polygons as

  8. Interactions among Radiation, Convection, and Large-Scale Dynamics in a General Circulation Model.

    NASA Astrophysics Data System (ADS)

    Randall, David A.; Harshvardhan; Dazlich, Donald A.; Corsetti, Thomas G.

    1989-07-01

    We have analyzed the effects of radiatively active clouds on the climate simulated by the UCLA/GLA GCM, with particular attention to the effects of the upper tropospheric stratiform clouds associated with deep cumulus convection, and the interactions of these clouds with convection and the large-scale circulation.Several numerical experiments have been performed to investigate the mechanisms through which the clouds influence the large-scale circulation. In the `NODETLQ' experiment, no liquid water or ice was detrained from cumulus clouds into the environment; all of the condensate was rained out. Upper level supersaturation cloudiness was drastically reduced, the atmosphere dried, and tropical outgoing longwave radiation increased. In the `NOANVIL' experiment, the radiative effects of the optically thich upper-level cloud sheets associated with deep cumulus convection were neglected. The land surface received more solar radiation in regions of convection, leading to enhanced surface fluxes and a dramatic increase in precipitation. In the `NOCRF' experiment, the longwave atmospheric cloud radiative forcing (ACRF) was omitted, paralleling the recent experiment of Slingo and Slingo. The results suggest that the ACRF enhances deep penetrative convection and precipitation, while suppressing shallow convection. They also indicate that the ACRF warms and moistens the tropical troposphere. The results of this experiment are somewhat ambiguous, however; for example, the ACRF suppresses precipitation in some parts of the tropics, and enhances it in others.To isolate the effects of the ACRF in a simpler setting, we have analyzed the climate of an ocean-covered Earth, which we call Seaworld. The key simplicities of Seaworld are the fixed boundary temperature with no land points, the lack of mountains, and the zonal uniformity of the boundary conditions. Results are presented from two Seaworld simulations. The first includes a full suite of physical parameterizations, while

  9. Petal, terrain & airbags - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Portions of the lander's deflated airbags and a petal are at the lower area of this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. The metallic object at lower right is part of the lander's low-gain antenna. This image is part of a 3D 'monster

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  10. Quantification of the gravity wave forcing of the migrating diurnal tide in a gravity wave-resolving general circulation model

    NASA Astrophysics Data System (ADS)

    Watanabe, Shingo; Miyahara, Saburo

    2009-04-01

    The interaction of gravity waves (GWs) and the migrating diurnal tide are studied in a GW-resolving general circulation model (GCM) by calculating the tidal components of zonal wind accelerations and equivalent Rayleigh friction due to tidal induced GW dissipation. Two 15-day periods for perpetual equinoctial and solstice simulations are analyzed, which are performed with the Japanese Atmospheric General circulation model for Upper Atmosphere Research (JAGUAR) high-resolution GCM. The model can directly simulate GWs with horizontal wavelengths greater than about 190 km, and, thus reproduce the general features of the mean winds and temperatures from the surface to the mesosphere and lower thermosphere (MLT). The amplitudes of the migrating diurnal tide are successfully simulated during both seasons, and the tidal winds affect the altitudes of GW dissipation in the low-latitude MLT. The tidal component of GW forcing has maximal values of about 15 m s-1 d-1 near the maximal vertical shears of the tidal winds and generally works to shorten the vertical wavelength of the migrating diurnal tide. The phase relationship between the tidal winds and the tidal induced GW forcing is not exactly 90° out of phase, causing amplification/suppression of the tide. The GW forcing amplifies the migrating diurnal tide during the equinox, while during the solstice, it suppresses the tidal winds in the upper mesosphere of both hemispheres. This difference in behavior can be attributed to a seasonal variation of the mean zonal winds, because combination of the mean and tidal winds affects the altitudes of GW dissipation.

  11. Multiyear Simulations of the Martian Water Cycle with the Ames General Circulation Model

    NASA Technical Reports Server (NTRS)

    Haberle, R. M.; Schaeffer, J. R.; Nelli, S. M.; Murphy, J. R.

    2003-01-01

    Mars atmosphere is carbon dioxide dominated with non-negligible amounts of water vapor and suspended dust particles. The atmospheric dust plays an important role in the heating and cooling of the planet through absorption and emission of radiation. Small dust particles can potentially be carried to great altitudes and affect the temperatures there. Water vapor condensing onto the dust grains can affect the radiative properties of both, as well as their vertical extent. The condensation of water onto a dust grain will change the grain s fall speed and diminish the possibility of dust obtaining high altitudes. In this capacity, water becomes a controlling agent with regard to the vertical distribution of dust. Similarly, the atmosphere s water vapor holding capacity is affected by the amount of dust in the atmosphere. Dust is an excellent green house catalyst; it raises the temperature of the atmosphere, and thus, its water vapor holding capacity. There is, therefore, a potentially significant interplay between the Martian dust and water cycles. Previous research done using global, 3-D computer modeling to better understand the Martian atmosphere treat the dust and the water cycles as two separate and independent processes. The existing Ames numerical model will be employed to simulate the relationship between the Martian dust and water cycles by actually coupling the two cycles. Water will condense onto the dust, allowing the particle's radiative characteristics, fall speeds, and as a result, their vertical distribution to change. Data obtained from the Viking, Mars Pathfinder, and especially the Mars Global Surveyor missions will be used to determine the accuracy of the model results.

  12. Circulation anomaly mechanisms in the tropical Atlantic sector during the Northeast Brazil rainy season: Results from the GISS general circulation model

    SciTech Connect

    Hastenrath, S.; Druyan, L.

    1993-08-20

    The role of the sea surface temperature (SST) pattern in the tropical Atlantic on the overlying atmosphere is studied from a 7-year run of the general circulation model (GCM) of the Goddard Institute for Space Studies (GISS) (period 1980-1986) and in comparison to upper air analyses of the European Centre for Medium-Range Weather Forecasts (ECMWF), surface ship observations of the SST and wind fields (COADS), and rainfall measurements in Northeast Brazil (Nordeste). Observations for March to April show that reduced northward SST decrease in the tropical Atlantic is accompanied by reduced northward decrease of lower-tropospheric thickness, which accounts for an inverse change in the meridional pressure gradient and reduced northerly wind component; this in turn entails a northward displaced Intertropical Convergence Zone and drought in the Nordeste. The GCM simulation reproduces the thermal and hydrostatic forcing of SST on the meridional gradients of lower-tropospheric thickness and pressure in the proper sense, albeit more weakly than observed. The modeled meridional wind component follows the meridional pressure gradient in the proper sense, but mean and range are smaller than observed, and the modeled interannual variability is not altogether consistent with observational evidence. Both modeled and observed March to April Nordeste rainfall are negatively related with SST anomalies in the equatorial Pacific in March to April as well as in the immediately preceding January. Both in January and in March to April the modeled soil moisture exhibits a strong dependence on the modeled precipitation, but neither resembles in interannual variability nor in absolute amounts of the observed rainfall. Overall the GISS GCM seems to reproduce reasonably well the response of lower-tropospheric thickness and near-surface pressure to SST, while the simulation of wind and rainfall is somewhat deficient. 27 refs., 4 figs.

  13. Three-Dimensional (3D) Distribution

    DTIC Science & Technology

    2009-03-11

    witnessed by ongoing efforts in both Afghanistan and Iraq , must turn distribution challenges into opportunities by mastering Three-Dimensional (3D...sustainment. 5 Joint Logistics Functions •Supply •Services •Maintenance •Transportation • Health Service Support •General Engineering Joint Personnel...Maintenance •Transportation • Health Service Support •Explosive Ordinance Disposal •Human Resource Support •Legal Support •Religious Support •Financial

  14. PLOT3D/AMES, GENERIC UNIX VERSION USING DISSPLA (WITHOUT TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. The UNIX/DISSPLA implementation of PLOT3D supports 2-D polygons as

  15. PLOT3D/AMES, GENERIC UNIX VERSION USING DISSPLA (WITH TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. The UNIX/DISSPLA implementation of PLOT3D supports 2-D polygons as

  16. Actual oxygen and suboxia representation: comparison of different ocean general circulation models

    NASA Astrophysics Data System (ADS)

    Duteil, O.; Oschlies, A.

    2010-12-01

    Oxygen is produced by photosynthesis in the light-lit surface waters, and quickly equilibrates with the atmosphere at the sea surface. In the ocean interior, oxygen is consumed during remineralization of organic matter exported from the euphotic surface and transported by ocean currents. Sluggish circulation combined with high export production lead to oxygen depletion and creation of suboxic regions. Although covering only a small fraction of the global ocean volume, these regions are of global biogeochemical significance, as they lead to a loss of fixed nitrogen from the ocean via denitrification and anaerobic ammonium oxidation (anammox). The mechanisms described above are reproduced in coupled biogeochemical - dynamical ocean models. We compare here oxygen and apparent oxygen utilization (AOU) distribution in 5 state-of-the-art models to observational data. Wide discrepancies, but also similar biases, are observed in term of suboxia extension and even mean oxygen content. These discrepancies are linked to the export production and also dynamical properties, such as overturning strength. The ratio of preformed over total nutrients has been computed to evaluate better relative impact of biological and physical pump in each case. Current study emphasizes the need of a better parameterization of oxygen compartment in ocean models.

  17. Assessment of the non-hydrostatic effect in general circulation models (GCMs)

    NASA Astrophysics Data System (ADS)

    Deng, Y.; Richmond, A. D.; Ridley, A. J.; Liu, H.

    2007-12-01

    Under hydrostatic equilibrium, a typical assumption used in global thermosphere ionosphere models, the pressure gradient in the vertical direction is exactly balanced by the gravity force. Using the Global Ionosphere Thermosphere Model (GITM), which solves the complete vertical momentum equation, the primary characteristics of non-hydrostatic effects on the upper atmosphere are investigated. Our results show that after a sudden intense enhancement of high-latitude Joule heating, the vertical pressure gradient force can locally be 25 percent larger than the gravity force, resulting in a significant disturbance away from hydrostatic equilibrium. This disturbance is transported from the lower altitude source region to high altitudes through an acoustic wave, which has been simulated in a global circulation model for the first time. Due to the conservation of perturbation energy, the magnitude of the vertical wind perturbation increases with altitude and reaches 150 (250) m/s at 300 (430) km during the disturbance. The upward neutral wind lifts the atmosphere and raises the neutral density at high altitudes by a factor of two. While the time scale of the buoyancy acceleration perturbation is around 5-10 minutes in this case, the large vertical wind (above 50 m/s) at 300 km altitude lasts for a significantly longer time, and depends on the lifetime of the forcing. These large vertical winds are observed and are not typically reproduced by hydrostatic models of the thermosphere and ionosphere.

  18. The Dynamics of Seasonal Change of the Long Waves as Deduced from a Low-Order General Circulation Model.

    NASA Astrophysics Data System (ADS)

    Otto-Bliesner, Bette Lou

    1980-08-01

    The purpose of this study is to gain a better understanding of the dynamics of seasonal change through analysis of long-term integrations of a global, low-order general circulation model. The behavior of the long waves, wavenumbers 1 through 5, are investigated in terms of vertically integrated and inter-harmonic exchanges of energy. The seasonal cycle is explored not only in the northern extratropics where observational data is available for comparison, but also in the tropics and southern extratropics where our current knowledge is incomplete. Special attention is given to the temporal variation of the statistics and step -function response of the circulation. The numerical model used in this study is a global, spectral, primitive equation model with five levels in the vertical and tri-angular truncation at wavenumber 10 in the horizontal. Included in the model are: orography; time-varying (but prescribed) sea-surface temperatures, snowcover, and solar declination angle; simplified parameterizations of radiation, convection, condensation, diffusion, and surface transports; and, a surface heat budget. The external seasonal forcing of the model atmosphere is composed of sinusoidal variations in the incoming solar radiation and latitude of the snowline and more complicated variations in the albedo of the snow and the sea-surface temperatures. A five year seasonal simulation has been analyzed. The model simulates the vertically integrated energetics of the long waves of the atmosphere reasonably well. The seasonal cycles and interannual variabilities of the energy statistics resemble those documented in observed studies. There are indications of asymmetric and steplike responses to the external seasonal forcing in the annual cycles of the energetics. The spring decrease of eddy kinetic energy at northern extratropical latitudes is less rapid than the fall increase. The fall increase is composed of equinoctial storminess periods which are characterized by an enhanced

  19. What is 3D good for? A review of human performance on stereoscopic 3D displays

    NASA Astrophysics Data System (ADS)

    McIntire, John P.; Havig, Paul R.; Geiselman, Eric E.

    2012-06-01

    This work reviews the human factors-related literature on the task performance implications of stereoscopic 3D displays, in order to point out the specific performance benefits (or lack thereof) one might reasonably expect to observe when utilizing these displays. What exactly is 3D good for? Relative to traditional 2D displays, stereoscopic displays have been shown to enhance performance on a variety of depth-related tasks. These tasks include judging absolute and relative distances, finding and identifying objects (by breaking camouflage and eliciting perceptual "pop-out"), performing spatial manipulations of objects (object positioning, orienting, and tracking), and navigating. More cognitively, stereoscopic displays can improve the spatial understanding of 3D scenes or objects, improve memory/recall of scenes or objects, and improve learning of spatial relationships and environments. However, for tasks that are relatively simple, that do not strictly require depth information for good performance, where other strong cues to depth can be utilized, or for depth tasks that lie outside the effective viewing volume of the display, the purported performance benefits of 3D may be small or altogether absent. Stereoscopic 3D displays come with a host of unique human factors problems including the simulator-sickness-type symptoms of eyestrain, headache, fatigue, disorientation, nausea, and malaise, which appear to effect large numbers of viewers (perhaps as many as 25% to 50% of the general population). Thus, 3D technology should be wielded delicately and applied carefully; and perhaps used only as is necessary to ensure good performance.

  20. The World of 3-D.

    ERIC Educational Resources Information Center

    Mayshark, Robin K.

    1991-01-01

    Students explore three-dimensional properties by creating red and green wall decorations related to Christmas. Students examine why images seem to vibrate when red and green pieces are small and close together. Instructions to conduct the activity and construct 3-D glasses are given. (MDH)

  1. 3D Printing: Exploring Capabilities

    ERIC Educational Resources Information Center

    Samuels, Kyle; Flowers, Jim

    2015-01-01

    As 3D printers become more affordable, schools are using them in increasing numbers. They fit well with the emphasis on product design in technology and engineering education, allowing students to create high-fidelity physical models to see and test different iterations in their product designs. They may also help students to "think in three…

  2. SNL3dFace

    SciTech Connect

    Russ, Trina; Koch, Mark; Koudelka, Melissa; Peters, Ralph; Little, Charles; Boehnen, Chris; Peters, Tanya

    2007-07-20

    This software distribution contains MATLAB and C++ code to enable identity verification using 3D images that may or may not contain a texture component. The code is organized to support system performance testing and system capability demonstration through the proper configuration of the available user interface. Using specific algorithm parameters the face recognition system has been demonstrated to achieve a 96.6% verification rate (Pd) at 0.001 false alarm rate. The system computes robust facial features of a 3D normalized face using Principal Component Analysis (PCA) and Fisher Linear Discriminant Analysis (FLDA). A 3D normalized face is obtained by alighning each face, represented by a set of XYZ coordinated, to a scaled reference face using the Iterative Closest Point (ICP) algorithm. The scaled reference face is then deformed to the input face using an iterative framework with parameters that control the deformed surface regulation an rate of deformation. A variety of options are available to control the information that is encoded by the PCA. Such options include the XYZ coordinates, the difference of each XYZ coordinates from the reference, the Z coordinate, the intensity/texture values, etc. In addition to PCA/FLDA feature projection this software supports feature matching to obtain similarity matrices for performance analysis. In addition, this software supports visualization of the STL, MRD, 2D normalized, and PCA synthetic representations in a 3D environment.

  3. Making Inexpensive 3-D Models

    ERIC Educational Resources Information Center

    Manos, Harry

    2016-01-01

    Visual aids are important to student learning, and they help make the teacher's job easier. Keeping with the "TPT" theme of "The Art, Craft, and Science of Physics Teaching," the purpose of this article is to show how teachers, lacking equipment and funds, can construct a durable 3-D model reference frame and a model gravity…

  4. The PRISM3D paleoenvironmental reconstruction

    USGS Publications Warehouse

    Dowsett, H.; Robinson, M.; Haywood, A.M.; Salzmann, U.; Hill, Daniel; Sohl, L.E.; Chandler, M.; Williams, Mark; Foley, K.; Stoll, D.K.

    2010-01-01

    The Pliocene Research, Interpretation and Synoptic Mapping (PRISM) paleoenvironmental reconstruction is an internally consistent and comprehensive global synthesis of a past interval of relatively warm and stable climate. It is regularly used in model studies that aim to better understand Pliocene climate, to improve model performance in future climate scenarios, and to distinguish model-dependent climate effects. The PRISM reconstruction is constantly evolving in order to incorporate additional geographic sites and environmental parameters, and is continuously refined by independent research findings. The new PRISM three dimensional (3D) reconstruction differs from previous PRISM reconstructions in that it includes a subsurface ocean temperature reconstruction, integrates geochemical sea surface temperature proxies to supplement the faunal-based temperature estimates, and uses numerical models for the first time to augment fossil data. Here we describe the components of PRISM3D and describe new findings specific to the new reconstruction. Highlights of the new PRISM3D reconstruction include removal of Hudson Bay and the Great Lakes and creation of open waterways in locations where the current bedrock elevation is less than 25m above modern sea level, due to the removal of the West Antarctic Ice Sheet and the reduction of the East Antarctic Ice Sheet. The mid-Piacenzian oceans were characterized by a reduced east-west temperature gradient in the equatorial Pacific, but PRISM3D data do not imply permanent El Niño conditions. The reduced equator-to-pole temperature gradient that characterized previous PRISM reconstructions is supported by significant displacement of vegetation belts toward the poles, is extended into the Arctic Ocean, and is confirmed by multiple proxies in PRISM3D. Arctic warmth coupled with increased dryness suggests the formation of warm and salty paleo North Atlantic Deep Water (NADW) and a more vigorous thermohaline circulation system that may

  5. Clouds-radiation interactions in a general circulation model: Impact upon the planetary radiation balance

    SciTech Connect

    Smith, L.D.; Vonder Haar, T.H. )

    1991-01-20

    The unique multimonth set of simultaneous Earth radiation budget observations and cloud amount estimates taken during the Nimbus 7 satellite mission from June 1979 to May 1980 was used to validate a long-term climate simulation obtained with the latest version of the National Center for Atmospheric Research (NCAR) Community Climate Model. The comparison focused on the temporal variability of the model-generated cloud and radiation fields versus satellite data with the aim to (1) test the model's ability to simulate short-term fluctuations; and (2) examine the impact of the treatment of the interactions between clouds, radiation, and the hydrologic cycle on the model's performance. The Nimbus 7 data set comprised broad-spectral-band observations of the outgoing infrared radiation and planetary albedo taken by the Earth radiation budget scanners and total cloud amount estimates derived from radiances measured by the Temperature Humidity Infrared Radiometer and Total Ozone Mapping Spectrometer. Model-simulated northern hemisphere summer and winter seasons were obtained from a 15-year time integration including a seasonal cycle. Although the global distributions of the seasonal average and standard deviation of the model-generated cloud and radiation fields agreed reasonably well with those obtained from satellite observations, the magnitude of the standard deviation of both fields was overestimated by about a factor of 2 over the whole globe. In view of the impact of clouds on the atmospheric circulation and its temporal variability, increased fluctuations in cloudiness may affect the sensitivity of the model-simulated climate to external forcings and it is desirable to implement stronger couplings between the various physical processes in the NCAR Community Climate Model.

  6. A GENERAL CIRCULATION MODEL FOR GASEOUS EXOPLANETS WITH DOUBLE-GRAY RADIATIVE TRANSFER

    SciTech Connect

    Rauscher, Emily; Menou, Kristen

    2012-05-10

    We present a new version of our code for modeling the atmospheric circulation on gaseous exoplanets, now employing a 'double-gray' radiative transfer scheme, which self-consistently solves for fluxes and heating throughout the atmosphere, including the emerging (observable) infrared flux. We separate the radiation into infrared and optical components, each with its own absorption coefficient, and solve standard two-stream radiative transfer equations. We use a constant optical absorption coefficient, while the infrared coefficient can scale as a power law with pressure; however, for simplicity, the results shown in this paper use a constant infrared coefficient. Here we describe our new code in detail and demonstrate its utility by presenting a generic hot Jupiter model. We discuss issues related to modeling the deepest pressures of the atmosphere and describe our use of the diffusion approximation for radiative fluxes at high optical depths. In addition, we present new models using a simple form for magnetic drag on the atmosphere. We calculate emitted thermal phase curves and find that our drag-free model has the brightest region of the atmosphere offset by {approx}12 Degree-Sign from the substellar point and a minimum flux that is 17% of the maximum, while the model with the strongest magnetic drag has an offset of only {approx}2 Degree-Sign and a ratio of 13%. Finally, we calculate rates of numerical loss of kinetic energy at {approx}15% for every model except for our strong-drag model, where there is no measurable loss; we speculate that this is due to the much decreased wind speeds in that model.

  7. Paleoclimatic tracers: An investigation using an atmospheric general circulation model under ice age conditions. 2. Water isotopes

    SciTech Connect

    Joussaume, S. ); Jouzel, J. Centre National de la Recherche Scientifique, Grenoble )

    1993-02-20

    The linear relationship observed between the water isotopic contents of precipitation and surface air temperatures leads to the use of the water isotopes, H[sub 2][sup 18]O and HDO, in paleoclimatology. Applied to the measurements of the isotopic content of paleowaters, like groundwaters and deep ice cores, this relationship is used to infer paleotemperatures. However, this interpretation of paleo-isotopic contents is only valid if the isotope-temperature relationship is not affected by climate change. To address this problem, the authors have developed a water isotope modeling inside an atmospheric general circulation model (AGCM) and performed simultations of both the present-day and Last Glacial Maximum (LGM) climatic conditions. AGCM are indeed the only appropriate tools able to account the whole complexity of the atmospheric circulation. For the present-day climate, preliminary results for January were presented by Joussaume et al. (1984) and are complemented by new simulations performed for both February and August climatic conditions with a higher-resolution version of the model. Model results are well corroborated by observations. They also exhibit some effects of the atmospheric circulation on the isotopic fields. For the simulated LGM climate, the model results compare well with paleoclimatic data of water isotopic contents, except for a higher than observed spatial variability. The overall patterns of the simulated [delta][sup 18]O-temperature relationship for the LGM climate are practically unchanged, which tends to comfort the use of water isotopes in paleoclimatology. However, concerning the deuterium excess, i.e., the relationship between oxyen 18 and deuterium, the model results are not sufficiently valid to allow a discussion of the use of deuterium excess in paleoclimatology. 46 refs., 14 figs., 7 tabs.

  8. Dynamics of Quasi 2D and 3D Co-rotating Vortex Merger

    NASA Astrophysics Data System (ADS)

    Khandekar, Akshay; Jacob, Jamey

    2013-11-01

    Merger of vortices is examined experimentally to compare the merger of slender parallel vortices generated either coincidentally or continuously. It is known that like-sign vortices rotate around a common center of circulation and merger between the vortices may occur under certain conditions. This merger is dependent on the strength of the vortex circulation, distance of separation between the centers of the two vortices, ReΓ , and vorticity distribution. Quasi-2D and 3D experimental data is examined and merger relations are derived. The former uses high aspect ratio rotating paddles in a tank and while the latter are from wing-tip vortices in a wind tunnel. The vortex merger tank generates slender co-rotating vortices and are examined using PIV, while in the wind tunnel two opposing wings are arranged at opposite angles of attack to generate a pair of vortices that merge downstream. A 5-hole probe is used to obtain 3D velocity vectors via wake survey, along with PIV. The procedure is performed in the wake at different distances to observe merger under different conditions. Temporally and spatially dependent relations in quasi-2D and 3D vortex merger are derived. Merger behavior is generally similar between the cases, but instabilities along quasi-2D vortices may affect.

  9. PLOT3D/AMES, UNIX SUPERCOMPUTER AND SGI IRIS VERSION (WITH TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. In addition to providing the advantages of performing complex

  10. PLOT3D/AMES, UNIX SUPERCOMPUTER AND SGI IRIS VERSION (WITHOUT TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. In addition to providing the advantages of performing complex

  11. Interannual Variability of Martian Global Dust Storms: Simulations with a Low-Order Model of the General Circulation

    NASA Technical Reports Server (NTRS)

    Pankine, A. A.; Ingersoll, Andrew P.

    2002-01-01

    We present simulations of the interannual variability of martian global dust storms (GDSs) with a simplified low-order model (LOM) of the general circulation. The simplified model allows one to conduct computationally fast long-term simulations of the martian climate system. The LOM is constructed by Galerkin projection of a 2D (zonally averaged) general circulation model (GCM) onto a truncated set of basis functions. The resulting LOM consists of 12 coupled nonlinear ordinary differential equations describing atmospheric dynamics and dust transport within the Hadley cell. The forcing of the model is described by simplified physics based on Newtonian cooling and Rayleigh friction. The atmosphere and surface are coupled: atmospheric heating depends on the dustiness of the atmosphere, and the surface dust source depends on the strength of the atmospheric winds. Parameters of the model are tuned to fit the output of the NASA AMES GCM and the fit is generally very good. Interannual variability of GDSs is possible in the IBM, but only when stochastic forcing is added to the model. The stochastic forcing could be provided by transient weather systems or some surface process such as redistribution of the sand particles in storm generating zones on the surface. The results are sensitive to the value of the saltation threshold, which hints at a possible feedback between saltation threshold and dust storm activity. According to this hypothesis, erodable material builds up its a result of a local process, whose effect is to lower the saltation threshold until a GDS occurs. The saltation threshold adjusts its value so that dust storms are barely able to occur.

  12. High-resolution numerical simulation of Venus atmosphere by AFES (Atmospheric general circulation model For the Earth Simulator)

    NASA Astrophysics Data System (ADS)

    Sugimoto, Norihiko; AFES project Team

    2016-10-01

    We have developed an atmospheric general circulation model (AGCM) for Venus on the basis of AFES (AGCM For the Earth Simulator) and performed a high-resolution simulation (e.g., Sugimoto et al., 2014a). The highest resolution is T639L120; 1920 times 960 horizontal grids (grid intervals are about 20 km) with 120 vertical layers (layer intervals are about 1 km). In the model, the atmosphere is dry and forced by the solar heating with the diurnal and semi-diurnal components. The infrared radiative process is simplified by adopting Newtonian cooling approximation. The temperature is relaxed to a prescribed horizontally uniform temperature distribution, in which a layer with almost neutral static stability observed in the Venus atmosphere presents. A fast zonal wind in a solid-body rotation is given as the initial state.Starting from this idealized superrotation, the model atmosphere reaches a quasi-equilibrium state within 1 Earth year and this state is stably maintained for more than 10 Earth years. The zonal-mean zonal flow with weak midlatitude jets has almost constant velocity of 120 m/s in latitudes between 45°S and 45°N at the cloud top levels, which agrees very well with observations. In the cloud layer, baroclinic waves develop continuously at midlatitudes and generate Rossby-type waves at the cloud top (Sugimoto et al., 2014b). At the polar region, warm polar vortex surrounded by a cold latitude band (cold collar) is well reproduced (Ando et al., 2016). As for horizontal kinetic energy spectra, divergent component is broadly (k > 10) larger than rotational component compared with that on Earth (Kashimura et al., in preparation). We will show recent results of the high-resolution run, e.g., small-scale gravity waves attributed to large-scale thermal tides. Sugimoto, N. et al. (2014a), Baroclinic modes in the Venus atmosphere simulated by GCM, Journal of Geophysical Research: Planets, Vol. 119, p1950-1968.Sugimoto, N. et al. (2014b), Waves in a Venus general

  13. General circulation models of the dynamics of Pluto's volatile transport on the eve of the New Horizons encounter

    NASA Astrophysics Data System (ADS)

    Toigo, Anthony D.; French, Richard G.; Gierasch, Peter J.; Guzewich, Scott D.; Zhu, Xun; Richardson, Mark I.

    2015-07-01

    Pluto's atmospheric dynamics occupy an interesting regime in which the radiative time constant is quite long, the combined effects of high obliquity and a highly eccentric orbit can produce strong seasonal variations in atmospheric pressure, and the strong coupling between the atmosphere and volatile transport on the surface results in atmospheric flows that are quite sensitive to surface and subsurface properties that at present are poorly constrained by direct observations. In anticipation of the New Horizons encounter with the Pluto system in July 2015, we present a Pluto-specific three-dimensional general circulation model (GCM), PlutoWRF, incorporating the most accurate current radiative transfer models of Pluto's atmosphere, a physically robust treatment of nitrogen volatile transport, and the flexibility to accommodate richly detailed information about the surface and subsurface conditions as new data become available. We solve for a physically self-consistent, equilibrated combination of surface, subsurface, and atmospheric conditions to specify the boundary conditions and initial state values for each GCM run. This is accomplished using two reduced versions of PlutoWRF: a two-dimensional surface volatile exchange model to specify the properties of surface nitrogen ice and the initial atmospheric surface pressure, and a one-dimensional radiative-conductive-convective model that uses the two-dimensional model predictions to determine the corresponding global-mean atmospheric thermal profile. We illustrate the capabilities of PlutoWRF in predicting Pluto's general circulation, thermal state, and volatile transport of nitrogen by calculating the dynamical response of Pluto's atmosphere, based on four different idealized models of Pluto's surface ice distribution from Young (Young, L.A. [2013]. Astrophys. J. 766, L22) and Hansen et al. (Hansen, C.J., Paige, D.A., Young, L.A. [2015]. Icarus 246, 183). Our GCM runs typically span 30 years, from 1985 to 2015

  14. Evaluating the skills of isotope-enabled general circulation models against in situ atmospheric water vapor isotope observations

    NASA Astrophysics Data System (ADS)

    Steen-Larsen, H. C.; Risi, C.; Werner, M.; Yoshimura, K.; Masson-Delmotte, V.

    2017-01-01

    The skills of isotope-enabled general circulation models are evaluated against atmospheric water vapor isotopes. We have combined in situ observations of surface water vapor isotopes spanning multiple field seasons (2010, 2011, and 2012) from the top of the Greenland Ice Sheet (NEEM site: 77.45°N, 51.05°W, 2484 m above sea level) with observations from the marine boundary layer of the North Atlantic and Arctic Ocean (Bermuda Islands 32.26°N, 64.88°W, year: 2012; south coast of Iceland 63.83°N, 21.47°W, year: 2012; South Greenland 61.21°N, 47.17°W, year: 2012; Svalbard 78.92°N, 11.92°E, year: 2014). This allows us to benchmark the ability to simulate the daily water vapor isotope variations from five different simulations using isotope-enabled general circulation models. Our model-data comparison documents clear isotope biases both on top of the Greenland Ice Sheet (1-11‰ for δ18O and 4-19‰ for d-excess depending on model and season) and in the marine boundary layer (maximum differences for the following: Bermuda δ18O = 1‰, d-excess = 3‰; South coast of Iceland δ18O = 2‰, d-excess = 5‰; South Greenland δ18O = 4‰, d-excess = 7‰; Svalbard δ18O = 2‰, d-excess = 7‰). We find that the simulated isotope biases are not just explained by simulated biases in temperature and humidity. Instead, we argue that these isotope biases are related to a poor simulation of the spatial structure of the marine boundary layer water vapor isotopic composition. Furthermore, we specifically show that the marine boundary layer water vapor isotopes of the Baffin Bay region show strong influence on the water vapor isotopes at the NEEM deep ice core-drilling site in northwest Greenland. Our evaluation of the simulations using isotope-enabled general circulation models also documents wide intermodel spatial variability in the Arctic. This stresses the importance of a coordinated water vapor isotope-monitoring network in order to discriminate amongst these model

  15. Prognostic residual mean flow in an ocean general circulation model and its relation to prognostic Eulerian mean flow

    SciTech Connect

    Saenz, Juan A.; Chen, Qingshan; Ringler, Todd

    2015-05-19

    Recent work has shown that taking the thickness-weighted average (TWA) of the Boussinesq equations in buoyancy coordinates results in exact equations governing the prognostic residual mean flow where eddy–mean flow interactions appear in the horizontal momentum equations as the divergence of the Eliassen–Palm flux tensor (EPFT). It has been proposed that, given the mathematical tractability of the TWA equations, the physical interpretation of the EPFT, and its relation to potential vorticity fluxes, the TWA is an appropriate framework for modeling ocean circulation with parameterized eddies. The authors test the feasibility of this proposition and investigate the connections between the TWA framework and the conventional framework used in models, where Eulerian mean flow prognostic variables are solved for. Using the TWA framework as a starting point, this study explores the well-known connections between vertical transfer of horizontal momentum by eddy form drag and eddy overturning by the bolus velocity, used by Greatbatch and Lamb and Gent and McWilliams to parameterize eddies. After implementing the TWA framework in an ocean general circulation model, we verify our analysis by comparing the flows in an idealized Southern Ocean configuration simulated using the TWA and conventional frameworks with the same mesoscale eddy parameterization.

  16. Prognostic residual mean flow in an ocean general circulation model and its relation to prognostic Eulerian mean flow

    DOE PAGES

    Saenz, Juan A.; Chen, Qingshan; Ringler, Todd

    2015-05-19

    Recent work has shown that taking the thickness-weighted average (TWA) of the Boussinesq equations in buoyancy coordinates results in exact equations governing the prognostic residual mean flow where eddy–mean flow interactions appear in the horizontal momentum equations as the divergence of the Eliassen–Palm flux tensor (EPFT). It has been proposed that, given the mathematical tractability of the TWA equations, the physical interpretation of the EPFT, and its relation to potential vorticity fluxes, the TWA is an appropriate framework for modeling ocean circulation with parameterized eddies. The authors test the feasibility of this proposition and investigate the connections between the TWAmore » framework and the conventional framework used in models, where Eulerian mean flow prognostic variables are solved for. Using the TWA framework as a starting point, this study explores the well-known connections between vertical transfer of horizontal momentum by eddy form drag and eddy overturning by the bolus velocity, used by Greatbatch and Lamb and Gent and McWilliams to parameterize eddies. After implementing the TWA framework in an ocean general circulation model, we verify our analysis by comparing the flows in an idealized Southern Ocean configuration simulated using the TWA and conventional frameworks with the same mesoscale eddy parameterization.« less

  17. Bioactive factors in uteroplacental and systemic circulation link placental ischemia to generalized vascular dysfunction in hypertensive pregnancy and preeclampsia.

    PubMed

    Shah, Dania A; Khalil, Raouf A

    2015-06-15

    Preeclampsia is a pregnancy-associated disorder characterized by hypertension, and could lead to maternal and fetal morbidity and mortality; however, the pathophysiological mechanisms involved are unclear. Predisposing demographic, genetic and environmental risk factors could cause localized abnormalities in uteroplacental cytoactive factors such as integrins, matrix metalloproteinases, cytokines and major histocompatibility complex molecules leading to decreased vascular remodeling, uteroplacental vasoconstriction, trophoblast cells apoptosis, and abnormal development of the placenta. Defective placentation and decreased trophoblast invasion of the myometrium cause reduction in uteroplacental perfusion pressure (RUPP) and placental ischemia/hypoxia, an important event in preeclampsia. RUPP could stimulate the release of circulating bioactive factors such as the anti-angiogenic factors soluble fms-like tyrosine kinase-1 and soluble endoglin that cause imbalance with the pro-angiogenic factors vascular endothelial growth factor and placental growth factor, or cause the release of inflammatory cytokines, reactive oxygen species, hypoxia-induced factor-1 and AT1 angiotensin receptor agonistic autoantibodies. The circulating bioactive factors target endothelial cells causing generalized endotheliosis, endothelial dysfunction, decreased vasodilators such as nitric oxide and prostacyclin and increased vasoconstrictors such as endothelin-1 and thromboxane A2, leading to increased vasoconstriction. The bioactive factors also stimulate the mechanisms of VSM contraction including Ca(2+), protein kinase C, and Rho-kinase and induce extracellular matrix remodeling leading to further vasoconstriction and hypertension. While therapeutic options are currently limited, understanding the underlying mechanisms could help design new interventions for management of preeclampsia.

  18. Bioactive Factors in Uteroplacental and Systemic Circulation Link Placental Ischemia to Generalized Vascular Dysfunction in Hypertensive Pregnancy and Preeclampsia

    PubMed Central

    Shah, Dania A.; Khalil, Raouf A.

    2015-01-01

    Preeclampsia is a pregnancy-associated disorder characterized by hypertension, and could lead to maternal and fetal morbidity and mortality; however, the pathophysiological mechanisms involved are unclear. Predisposing demographic, genetic and environmental risk factors could cause localized abnormalities in uteroplacental cytoactive factors such as integrins, matrix metalloproteinases, cytokines and major histocompatibility complex molecules leading to decreased vascular remodeling, uteroplacental vasoconstriction, trophoblast cells apoptosis, and abnormal development of the placenta. Defective placentation and decreased trophoblast invasion of the myometrium cause reduction in uteroplacental perfusion pressure (RUPP) and placental ischemia/hypoxia, an important event in preeclampsia. RUPP could stimulate the release of circulating bioactive factors such as the anti-angiogenic factors soluble fms-like tyrosine kinase-1 and soluble endoglin that cause imbalance with the pro-angiogenic factors vascular endothelial growth factor and placental growth factor, or cause the release of inflammatory cytokines, reactive oxygen species, hypoxia-induced factor-1 and AT1 angiotensin receptor agonistic autoantibodies. The circulating bioactive factors target endothelial cells causing generalized endotheliosis, endothelial dysfunction, decreased vasodilators such as nitric oxide and prostacyclin and increased vasoconstrictors such as endothelin-1 and thromboxane A2, leading to increased vasoconstriction. The bioactive factors also stimulate the mechanisms of VSM contraction including Ca2+, protein kinase C, and Rho-kinase and induce extracellular matrix remodeling leading to further vasoconstriction and hypertension. While therapeutic options are currently limited, understanding the underlying mechanisms could help design new interventions for management of preeclampsia. PMID:25916268

  19. PLOT3D/AMES, SGI IRIS VERSION (WITHOUT TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. In each of these areas, the IRIS implementation of PLOT3D offers

  20. PLOT3D/AMES, SGI IRIS VERSION (WITH TURB3D)

    NASA Technical Reports Server (NTRS)

    Buning, P.

    1994-01-01

    five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. In each of these areas, the IRIS implementation of PLOT3D offers

  1. Gap Opening in 3D: Single-planet Gaps

    NASA Astrophysics Data System (ADS)

    Fung, Jeffrey; Chiang, Eugene

    2016-12-01

    Giant planets can clear deep gaps when embedded in 2D (razor-thin) viscous circumstellar disks. We show by direct simulation that giant planets are just as capable of carving out gaps in 3D. Surface density maps are similar between 2D and 3D, even in detail. In particular, the scaling {{{Σ }}}{gap}\\propto {q}-2 of gap surface density with planet mass, derived from a global “zero-dimensional” balance of Lindblad and viscous torques, applies equally well to results obtained at higher dimensions. Our 3D simulations reveal extensive, near-sonic, meridional flows both inside and outside the gaps; these large-scale circulations might bear on disk compositional gradients, in dust or other chemical species. At high planet mass, gap edges are mildly Rayleigh unstable and intermittently shed streams of material into the gap—less so in 3D than in 2D.

  2. Mixed boundary conditions in ocean general circulation models and their influence on the stability of the model`s conveyor belt

    SciTech Connect

    Mikolajewicz, U.; Maier-reimer, E.

    1994-11-01

    When driven under `mixed boundary conditions` coarse resolution ocean general circulation models (OGCMs) generally show a high sensitivity of the present-day thermohaline circulation against perturbations. We will show that an alternative formulation of the boundary condition for temperature, a mixture of prescribed heat fluxes and additional restoring of the sea surface temperature to a climatological boundary temperature with a longer time constant, drastically alters the stability of the modes of the thermohaline circulation. The results from simulations with the Hamburg large-scale geostrophic OGCM indicate that the stability of the mode of the thermohaline circulation with formation of North Atlantic deepwater increases, if the damping of sea surface temperature anomalies is reduced, whereas the opposite is true for the mode without North Atlantic deep water formation. It turns out that the formulation of the temperature boundary condition also affects the variability of the model.

  3. Forensic 3D scene reconstruction

    NASA Astrophysics Data System (ADS)

    Little, Charles Q.; Small, Daniel E.; Peters, Ralph R.; Rigdon, J. B.

    2000-05-01

    Traditionally law enforcement agencies have relied on basic measurement and imaging tools, such as tape measures and cameras, in recording a crime scene. A disadvantage of these methods is that they are slow and cumbersome. The development of a portable system that can rapidly record a crime scene with current camera imaging, 3D geometric surface maps, and contribute quantitative measurements such as accurate relative positioning of crime scene objects, would be an asset to law enforcement agents in collecting and recording significant forensic data. The purpose of this project is to develop a fieldable prototype of a fast, accurate, 3D measurement and imaging system that would support law enforcement agents to quickly document and accurately record a crime scene.

  4. 3D Printed Robotic Hand

    NASA Technical Reports Server (NTRS)

    Pizarro, Yaritzmar Rosario; Schuler, Jason M.; Lippitt, Thomas C.

    2013-01-01

    Dexterous robotic hands are changing the way robots and humans interact and use common tools. Unfortunately, the complexity of the joints and actuations drive up the manufacturing cost. Some cutting edge and commercially available rapid prototyping machines now have the ability to print multiple materials and even combine these materials in the same job. A 3D model of a robotic hand was designed using Creo Parametric 2.0. Combining "hard" and "soft" materials, the model was printed on the Object Connex350 3D printer with the purpose of resembling as much as possible the human appearance and mobility of a real hand while needing no assembly. After printing the prototype, strings where installed as actuators to test mobility. Based on printing materials, the manufacturing cost of the hand was $167, significantly lower than other robotic hands without the actuators since they have more complex assembly processes.

  5. Comparing swimsuits in 3D.

    PubMed

    van Geer, Erik; Molenbroek, Johan; Schreven, Sander; deVoogd-Claessen, Lenneke; Toussaint, Huib

    2012-01-01

    In competitive swimming, suits have become more important. These suits influence friction, pressure and wave drag. Friction drag is related to the surface properties whereas both pressure and wave drag are greatly influenced by body shape. To find a relationship between the body shape and the drag, the anthropometry of several world class female swimmers wearing different suits was accurately defined using a 3D scanner and traditional measuring methods. The 3D scans delivered more detailed information about the body shape. On the same day the swimmers did performance tests in the water with the tested suits. Afterwards the result of the performance tests and the differences found in body shape was analyzed to determine the deformation caused by a swimsuit and its effect on the swimming performance. Although the amount of data is limited because of the few test subjects, there is an indication that the deformation of the body influences the swimming performance.

  6. Forensic 3D Scene Reconstruction

    SciTech Connect

    LITTLE,CHARLES Q.; PETERS,RALPH R.; RIGDON,J. BRIAN; SMALL,DANIEL E.

    1999-10-12

    Traditionally law enforcement agencies have relied on basic measurement and imaging tools, such as tape measures and cameras, in recording a crime scene. A disadvantage of these methods is that they are slow and cumbersome. The development of a portable system that can rapidly record a crime scene with current camera imaging, 3D geometric surface maps, and contribute quantitative measurements such as accurate relative positioning of crime scene objects, would be an asset to law enforcement agents in collecting and recording significant forensic data. The purpose of this project is to develop a feasible prototype of a fast, accurate, 3D measurement and imaging system that would support law enforcement agents to quickly document and accurately record a crime scene.

  7. 3D-graphite structure

    SciTech Connect

    Belenkov, E. A. Ali-Pasha, V. A.

    2011-01-15

    The structure of clusters of some new carbon 3D-graphite phases have been calculated using the molecular-mechanics methods. It is established that 3D-graphite polytypes {alpha}{sub 1,1}, {alpha}{sub 1,3}, {alpha}{sub 1,5}, {alpha}{sub 2,1}, {alpha}{sub 2,3}, {alpha}{sub 3,1}, {beta}{sub 1,2}, {beta}{sub 1,4}, {beta}{sub 1,6}, {beta}{sub 2,1}, and {beta}{sub 3,2} consist of sp{sup 2}-hybridized atoms, have hexagonal unit cells, and differ in regards to the structure of layers and order of their alternation. A possible way to experimentally synthesize new carbon phases is proposed: the polymerization and carbonization of hydrocarbon molecules.

  8. Scalable large format 3D displays

    NASA Astrophysics Data System (ADS)

    Chang, Nelson L.; Damera-Venkata, Niranjan

    2010-02-01

    We present a general framework for the modeling and optimization of scalable large format 3-D displays using multiple projectors. Based on this framework, we derive algorithms that can robustly optimize the visual quality of an arbitrary combination of projectors (e.g. tiled, superimposed, combinations of the two) without manual adjustment. The framework creates for the first time a new unified paradigm that is agnostic to a particular configuration of projectors yet robustly optimizes for the brightness, contrast, and resolution of that configuration. In addition, we demonstrate that our algorithms support high resolution stereoscopic video at real-time interactive frame rates achieved on commodity graphics hardware. Through complementary polarization, the framework creates high quality multi-projector 3-D displays at low hardware and operational cost for a variety of applications including digital cinema, visualization, and command-and-control walls.

  9. Determination of humidity and temperature fluctuations based on MOZAIC data and parametrisation of persistent contrail coverage for general circulation models

    NASA Astrophysics Data System (ADS)

    Gierens, K. M.; Schumann, U.; Smit, H. G. J.; Helten, M.; Zängl, G.

    1997-08-01

    Humidity and temperature fluctuations at pressure levels between 166 and 290 hPa on the grid scale of general circulation models for a region covered by the routes of airliners, mainly over the Atlantic, have been determined by evaluation of the data obtained with almost 2000 flights within the MOZAIC programme. It is found that the distributions of the fluctuations cannot be modelled by Gaussian distributions, because large fluctuations appear with a relatively high frequency. Lorentz distributions were used for the analytical representation of the fluctuation distributions. From these a joint probability distribution has been derived for simultaneous temperature and humidity fluctuations. This function together with the criteria for the formation and persistence of contrails are used to derive the maximum possible fractional coverage of persistent contrails in a grid cell of a GCM. This can be employed in a statistical formulation of contrail appearance in a climate model.

  10. Surface energy balances of three general circulation models: Current climate and response to increasing atmospheric CO{sub 2}

    SciTech Connect

    Gutowski, W.J.; Gutzler, D.S.; Portman, D.; Wang, W.C.

    1988-04-01

    The surface energy balance simulated by state-of-the-art general circulation models at GFDL, GISS and NCAR for climates with current levels of atmospheric CO{sub 2} concentration (control climate) and with twice the current levels. The work is part of an effort sponsored by the US Department of Energy to assess climate simulations produced by these models. The surface energy balance enables us to diagnose differences between models in surface temperature climatology and sensitivity to doubling CO{sub 2} in terms of the processes that control surface temperature. Our analysis compares the simulated balances by averaging the fields of interest over a hierarchy of spatial domains ranging from the entire globe down to regions a few hundred kilometers across.

  11. Surface energy balances of three general circulation models: Current climate and response to increasing atmospheric CO[sub 2

    SciTech Connect

    Gutowski, W.J.; Gutzler, D.S.; Portman, D.; Wang, W.C.

    1988-04-01

    The surface energy balance simulated by state-of-the-art general circulation models at GFDL, GISS and NCAR for climates with current levels of atmospheric CO[sub 2] concentration (control climate) and with twice the current levels. The work is part of an effort sponsored by the US Department of Energy to assess climate simulations produced by these models. The surface energy balance enables us to diagnose differences between models in surface temperature climatology and sensitivity to doubling CO[sub 2] in terms of the processes that control surface temperature. Our analysis compares the simulated balances by averaging the fields of interest over a hierarchy of spatial domains ranging from the entire globe down to regions a few hundred kilometers across.

  12. Troposphere-stratosphere (surface-55 km) monthly winter general circulation statistics for the Northern Hemisphere Interannual variations

    NASA Technical Reports Server (NTRS)

    Geller, M. A.; Wu, M.-F.; Gelman, M. E.

    1984-01-01

    Individual monthly mean general circulation statistics for the Northern Hemisphere winters of 1978-79, 1979-80, 1980-81, and 1981-82 are examined for the altitude region from the earth's surface to 55 km. Substantial interannual variability is found in the mean zonal geostrophic wind; planetary waves with zonal wavenumber one and two; the heat and momentum fluxes; and the divergence of the Eliassen-Palm flux. These results are compared with previous studies by other workers. This variability in the monthly means is examined further by looking at both time-latitude sections at constant pressure levels and time-height sections at constant latitudes. The implications of this interannual variability for verifying models and interpreting observations are discussed.

  13. Coupling Planet Simulator Mars, a general circulation model of the Martian atmosphere, to the ice sheet model SICOPOLIS

    NASA Astrophysics Data System (ADS)

    Stenzel, O. J.; Grieger, B.; Keller, H. U.; Greve, R.; Fraedrich, K.; Kirk, E.; Lunkeit, F.

    2007-11-01

    A general circulation model of the Martian Atmosphere is coupled with a 3-dimensional polythermal ice-sheet model of the polar ice caps. With this combination a series of experiments is carried out to investigate the impact of long-term obliquity change on the Martian north polar ice cap (NPC). The behaviour of the NPC is tested under obliquities of θ=15∘, 25∘ and 35∘. With increasing obliquity the area covered by the NPC gets smaller but does not vanish. However, when started from an ice-free condition the models develop an ice cap only for low obliquities. The 'critical' obliquity at which a build-up of a new polar cap is possible is θ=22∘.

  14. Comparison of the Martian thermospheric density and temperature from IUVS/MAVEN data and general circulation modeling

    NASA Astrophysics Data System (ADS)

    Medvedev, Alexander S.; Nakagawa, Hiromu; Mockel, Chris; Yiǧit, Erdal; Kuroda, Takeshi; Hartogh, Paul; Terada, Kaori; Terada, Naoki; Seki, Kanako; Schneider, Nicholas M.; Jain, Sonal K.; Evans, J. Scott; Deighan, Justin I.; McClintock, William E.; Lo, Daniel; Jakosky, Bruce M.

    2016-04-01

    Newly released Imaging Ultraviolet Spectrograph/Mars Atmosphere and Volatile EvolutioN (IUVS/MAVEN) measurements of CO2 density in the Martian thermosphere have been used for comparison with the predictions of the Max Planck Institute Martian General Circulation Model (MPI-MGCM). The simulations reproduced (within one standard deviation) the available zonal mean density and derived temperature above 130 km. The MGCM replicated the observed dominant zonal wave number 3 nonmigrating tide and demonstrated that it represents a nonmoving imprint of the topography in the thermosphere. The comparison shows a great dependence of the simulated density and temperature to the prescribed solar flux, atomic oxygen abundances and gravity wave effects, with the former two being especially important in the thermosphere above 130 km and the latter playing a significant role both in the mesosphere and thermosphere.

  15. Analysis of a general circulation model product. I - Frontal systems in the Brazil/Malvinas and Kuroshio/Oyashio regions

    NASA Technical Reports Server (NTRS)

    Garzoli, Silvia L.; Garraffo, Zulema; Podesta, Guillermo; Brown, Otis

    1992-01-01

    The general circulation model (GCM) of Semtner and Chervin (1992) is tested by comparing the fields produced by this model with available observations in two western boundary current regions, the Brazil/Malvinas and the Kuroshio/Oyashio confluences. The two sets of data used are the sea surface temperature from satellite observations and the temperature field product from the GCM at levels 1 (12.5 m), 2 (37.5 m), and 6 (160 m). It is shown that the model reproduces intense thermal fronts at the sea surface and in the upper layers (where they are induced by the internal dynamics of the model). The location of the fronts are reproduced in the model within 4 to 5 deg, compared with observations. However, the variability of these fronts was found to be less pronounced in the model than in the observations.

  16. Comparison of climate time series produced by General Circulation Models and by observed data on a global scale

    NASA Astrophysics Data System (ADS)

    Filippidou, Ariadni Maria; Andrianopoulos, Alexandros; Argyrakis, Christos; Evgenia Chomata, Loukia; Dagalaki, Vasiliki; Grigoris, Xenofon; Kokkoris, Thanasis S.; Nasioka, Maria; Papazoglou, Konstantina A.; Papalexiou, Simon Michael; Tyralis, Hristos; Koutsoyiannis, Demetris

    2014-05-01

    Outputs of General Circulation Models (GCMs) for various climate variables such as temperature and precipitation are compared with time series produced from observations. Comparison is made on global and hemispheric spatial scale and on annual time scale. Various time periods are examined, distinguishing periods before and after publishing of model outputs. Historical climate time series are compared with the outputs of GCMs for the 20th century and those for the A1B, B1 and A2 emission scenarios for the 21st century. Several indices are examined, i.e. the estimated means, variances, Hurst parameters, cross-correlations etc. Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

  17. Liquid and Ice Cloud Microphysics in the CSU General Circulation Model. Part III: Sensitivity to Modeling Assumptions.

    NASA Astrophysics Data System (ADS)

    Fowler, Laura D.; Randall, David A.

    1996-03-01

    The inclusion of cloud microphysical processes in general circulation models makes it possible to study the multiple interactions among clouds, the hydrological cycle, and radiation. The gaps between the temporal and spatial scales at which such cloud microphysical processes work and those at which general circulation models presently function force climate modelers to crudely parameterize and simplify the various interactions among the different water species (namely, water vapor, cloud water, cloud ice, rain, and snow) and to use adjustable parameters to which large-scale models can be highly sensitive. Accordingly, the authors have investigated the sensitivity of the climate, simulated with the Colorado State University general circulation model, to various aspects of the parameterization of cloud microphysical processes and its interactions with the cumulus convection and radiative transfer parameterizations.The results of 120-day sensitivity experiments corresponding to perpetual January conditions have been compared with those of a control simulation in order to 1 ) determine the importance of advecting cloud water, cloud ice, rain, and snow at the temporal and spatial scale resolutions presently used in the model; 2) study the importance of the formation of extended stratiform anvils at the tops of cumulus towers, 3) analyze the role of mixed-phase clouds in determining the partitioning among cloud water, cloud ice, rain, and snow and, hence, their impacts on the simulated cloud optical properties; 4) evaluate the sensitivity of the atmospheric moisture budget and precipitation rates to a change in the fall velocities of rain and snow; 5) determine the model's sensitivity to the prescribed thresholds of autoconversion of cloud water to rain and cloud ice to snow; and 6) study the impact of the collection of supercooled cloud water by snow, as well as accounting for the cloud optical properties of snow.Results are presented in terms of 30-day mean differences

  18. Effects of surface current-wind interaction in an eddy-rich general ocean circulation simulation of the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Dietze, Heiner; Löptien, Ulrike

    2016-08-01

    Deoxygenation in the Baltic Sea endangers fish yields and favours noxious algal blooms. Yet, vertical transport processes ventilating the oxygen-deprived waters at depth and replenishing nutrient-deprived surface waters (thereby fuelling export of organic matter to depth) are not comprehensively understood. Here, we investigate the effects of the interaction between surface currents and winds on upwelling in an eddy-rich general ocean circulation model of the Baltic Sea. Contrary to expectations we find that accounting for current-wind effects inhibits the overall vertical exchange between oxygenated surface waters and oxygen-deprived water at depth. At major upwelling sites, however (e.g. off the southern coast of Sweden and Finland) the reverse holds: the interaction between topographically steered surface currents with winds blowing over the sea results in a climatological sea surface temperature cooling of 0.5 K. This implies that current-wind effects drive substantial local upwelling of cold and nutrient-replete waters.

  19. Diurnal variability of the hydrologic cycle in a general circulation model

    NASA Technical Reports Server (NTRS)

    Randall, David A.; Dazlich, Donald A.; HARSHVARDHAN

    1991-01-01

    In the present Colorado State University GCM simulation-based analysis of the diurnal and semidiurnal variability of precipitation, precipitable water, evaporation, cloudiness, horizontal moisture flux convergence, and cloud radiative forcing, a realistic afternoon precipitation maximum is obtained over land in warm rainy regions, as well as an early morning maximum over the oceans. The model has been further used to investigate the bases for the oceanic diurnal-precipitation cycle; the results thus obtained indicate that such an oceanic cycle occurs even in the absence of neighboring continents, and tends to have a morning maximum, although the observed phenomenon is generally stronger than the results indicate.

  20. [Real time 3D echocardiography

    NASA Technical Reports Server (NTRS)

    Bauer, F.; Shiota, T.; Thomas, J. D.

    2001-01-01

    Three-dimensional representation of the heart is an old concern. Usually, 3D reconstruction of the cardiac mass is made by successive acquisition of 2D sections, the spatial localisation and orientation of which require complex guiding systems. More recently, the concept of volumetric acquisition has been introduced. A matricial emitter-receiver probe complex with parallel data processing provides instantaneous of a pyramidal 64 degrees x 64 degrees volume. The image is restituted in real time and is composed of 3 planes (planes B and C) which can be displaced in all spatial directions at any time during acquisition. The flexibility of this system of acquisition allows volume and mass measurement with greater accuracy and reproducibility, limiting inter-observer variability. Free navigation of the planes of investigation allows reconstruction for qualitative and quantitative analysis of valvular heart disease and other pathologies. Although real time 3D echocardiography is ready for clinical usage, some improvements are still necessary to improve its conviviality. Then real time 3D echocardiography could be the essential tool for understanding, diagnosis and management of patients.

  1. Expected changes in future agro-climatological conditions in Northeast Thailand and their differences between general circulation models

    NASA Astrophysics Data System (ADS)

    Masaki, Yoshimitsu; Ishigooka, Yasushi; Kuwagata, Tsuneo; Goto, Shinkichi; Sawano, Shinji; Hasegawa, Toshihiro

    2011-12-01

    We have studied future changes in the atmospheric and hydrological environments in Northeast Thailand from the viewpoint of risk assessment of future cultural environments in crop fields. To obtain robust and reliable estimation for future climate, ten general circulation models under three warming scenarios, B1, A1B, and A2, were used in this study. The obtained change trends show that daily maximum air temperature and precipitation will increase by 2.6°C and 4.0%, respectively, whereas soil moisture will decrease by c.a. 1% point in volumetric water content at the end of this century under the A1B scenario. Seasonal contrasts in precipitation will intensify: precipitation increases in the rainy season and precipitation decreases in the dry season. Soil moisture will slightly decrease almost throughout the year. Despite a homogeneous increase in the air temperature over Northeast Thailand, a future decrease in soil water content will show a geographically inhomogeneous distribution: Soil will experience a relative larger decrease in wetness at a shallow depth on the Khorat plateau than in the surrounding mountainous area, reflecting vegetation cover and soil texture. The predicted increase in air temperature is relatively consistent between general circulation models. In contrast, relatively large intermodel differences in precipitation, especially in long-term trends, produce unwanted bias errors in the estimation of other hydrological elements, such as soil moisture and evaporation, and cause uncertainties in projection of the agro-climatological environment. Offline hydrological simulation with a wide precipitation range is one strategy to compensate for such uncertainties and to obtain reliable risk assessment of future cultural conditions in rainfed paddy fields in Northeast Thailand.

  2. Seasonal Distributions of Global Ocean Chlorophyll and Nutrients: Analysis with a Coupled Ocean General Circulation Biogeochemical, and Radiative Model

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.

    1999-01-01

    A coupled general ocean circulation, biogeochemical, and radiative model was constructed to evaluate and understand the nature of seasonal variability of chlorophyll and nutrients in the global oceans. The model is driven by climatological meteorological conditions, cloud cover, and sea surface temperature. Biogeochemical processes in the model are determined from the influences of circulation and turbulence dynamics, irradiance availability, and the interactions among three functional phytoplankton groups (diatoms, chorophytes, and picoplankton) and three nutrient groups (nitrate, ammonium, and silicate). Phytoplankton groups are initialized as homogeneous fields horizontally and vertically, and allowed to distribute themselves according to the prevailing conditions. Basin-scale model chlorophyll results are in very good agreement with CZCS pigments in virtually every global region. Seasonal variability observed in the CZCS is also well represented in the model. Synoptic scale (100-1000 km) comparisons of imagery are also in good conformance, although occasional departures are apparent. Agreement of nitrate distributions with in situ data is even better, including seasonal dynamics, except for the equatorial Atlantic. The good agreement of the model with satellite and in situ data sources indicates that the model dynamics realistically simulate phytoplankton and nutrient dynamics on synoptic scales. This is especially true given that initial conditions are homogenous chlorophyll fields. The success of the model in producing a reasonable representation of chlorophyll and nutrient distributions and seasonal variability in the global oceans is attributed to the application of a generalized, processes-driven approach as opposed to regional parameterization, and the existence of multiple phytoplankton groups with different physiological and physical properties. These factors enable the model to simultaneously represent the great diversity of physical, biological

  3. An eddy resolving numerical study of the general circulation and deep-water formation in the Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Mantziafou, A.; Lascaratos, A.

    2004-07-01

    General circulation and deep-water formation (DWF) processes in the Adriatic basin in a climatological year were numerically simulated in a high-resolution (1/20th of a degree) implementation of the Princeton Ocean Model (POM). The "perpetual" year atmospheric data were computed from the ECMWF Reanalysis data (1°×1°) covering the period 1979-1994. The model reproduces the main basin features of the general circulation, water mass distribution and their seasonal variability. The Adriatic Deep Water exiting through the Otranto Strait is produced with two different mechanisms inside the basin: (a) by open ocean deep convection over the Southern Adriatic Pit and Middle Adriatic Pit (b) on the continental shelf of the Northern and Middle Adriatic. The estimated contributions of both mechanisms suggest that 82% of the Adriatic Deep Water is formed inside the Southern Adriatic Pit, while all the higher density water in this water mass comes from the northern regions. The role of mesoscale eddies at the periphery of the dense-water chimney in the Southern Adriatic Pit was examined and their contribution to the lateral buoyancy flux, during the convection process, found to be small. The DWF rate at Otranto Strait is 0.28 Sv with σθ over 29.15. The sensitivity of the DWF processes to interannual variability of the buoyancy forcing and river runoff was assessed with a number of process-study numerical experiments. In these experiments the effect of an imposed "extreme" buoyancy forcing during 1 year, on the DWF rates, was to modify them during the specific year, but the effects were still present in the following normal climatological year. This shows that the DWF rates and their mass characteristics at a specific year depend not only on the atmospheric conditions prevailing that specific year but on the previous year's as well, thus leading to the concept of a "memory" of the basin.

  4. Alignment of continuous video onto 3D point clouds.

    PubMed

    Zhao, Wenyi; Nister, David; Hsu, Steve

    2005-08-01

    We propose a general framework for aligning continuous (oblique) video onto 3D sensor data. We align a point cloud computed from the video onto the point cloud directly obtained from a 3D sensor. This is in contrast to existing techniques where the 2D images are aligned to a 3D model derived from the 3D sensor data. Using point clouds enables the alignment for scenes full of objects that are difficult to model; for example, trees. To compute 3D point clouds from video, motion stereo is used along with a state-of-the-art algorithm for camera pose estimation. Our experiments with real data demonstrate the advantages of the proposed registration algorithm for texturing models in large-scale semiurban environments. The capability to align video before a 3D model is built from the 3D sensor data offers new practical opportunities for 3D modeling. We introduce a novel modeling-through-registration approach that fuses 3D information from both the 3D sensor and the video. Initial experiments with real data illustrate the potential of the proposed approach.

  5. Climate sensitivity due to increased CO2: experiments with a coupled atmosphere and ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Washington, Warren M.; Meehl, Gerald A.

    1989-06-01

    A version of the National Center for Atmospheric Research community climate model — a global, spectral (R15) general circulation model — is coupled to a coarse-grid (5° latitude-] longitude, four-layer) ocean general circulation model to study the response of the climate system to increases of atmospheric carbon dioxide (CO2). Three simulations are run: one with an instantaneous doubling of atmospheric CO2 (from 330 to 660 ppm), another with the CO2 concentration starting at 330 ppm and increasing linearly at a rate of 1% per year, and a third with CO2 held constant at 330 pm. Results at the end of 30 years of simulation indicate a globally averaged surface air temperature increase of 1.6° C for the instantaneous doubling case and 0.7°C for the transient forcing case. Inherent characteristics of the coarse-grid ocean model flow sea-surface temperatures (SSTs) in the tropics and higher-than-observed SSTs and reduced sea-ice extent at higher latitudes] produce lower sensitivity in this model after 30 years than in earlier simulations with the same atmosphere coupled to a 50-m, slab-ocean mixed layer. Within the limitations of the simulated meridional overturning, the thermohaline circulation weakens in the coupled model with doubled CO2 as the high-latitude ocean-surface layer warms and freshens and westerly wind stress is decreased. In the transient forcing case with slowly increasing CO2 (30% increase after 30 years), the zonal mean warming of the ocean is most evident in the surface layer near 30° 50° S. Geographical plots of surface air temperature change in the transient case show patterns of regional climate anomalies that differ from those in the instantaneous CO2 doubling case, particularly in the North Atlantic and northern European regions. This suggests that differences in CO2 forcing in the climate system are important in CO2 response in regard to time-dependent climate anomaly regimes. This confirms earlier studies with simple climate models

  6. GPU-Accelerated Denoising in 3D (GD3D)

    SciTech Connect

    2013-10-01

    The raw computational power GPU Accelerators enables fast denoising of 3D MR images using bilateral filtering, anisotropic diffusion, and non-local means. This software addresses two facets of this promising application: what tuning is necessary to achieve optimal performance on a modern GPU? And what parameters yield the best denoising results in practice? To answer the first question, the software performs an autotuning step to empirically determine optimal memory blocking on the GPU. To answer the second, it performs a sweep of algorithm parameters to determine the combination that best reduces the mean squared error relative to a noiseless reference image.

  7. Numerical Optimization Strategy for Determining 3D Flow Fields in Microfluidics

    NASA Astrophysics Data System (ADS)

    Eden, Alex; Sigurdson, Marin; Mezic, Igor; Meinhart, Carl

    2015-11-01

    We present a hybrid experimental-numerical method for generating 3D flow fields from 2D PIV experimental data. An optimization algorithm is applied to a theory-based simulation of an alternating current electrothermal (ACET) micromixer in conjunction with 2D PIV data to generate an improved representation of 3D steady state flow conditions. These results can be used to investigate mixing phenomena. Experimental conditions were simulated using COMSOL Multiphysics to solve the temperature and velocity fields, as well as the quasi-static electric fields. The governing equations were based on a theoretical model for ac electrothermal flows. A Nelder-Mead optimization algorithm was used to achieve a better fit by minimizing the error between 2D PIV experimental velocity data and numerical simulation results at the measurement plane. By applying this hybrid method, the normalized RMS velocity error between the simulation and experimental results was reduced by more than an order of magnitude. The optimization algorithm altered 3D fluid circulation patterns considerably, providing a more accurate representation of the 3D experimental flow field. This method can be generalized to a wide variety of flow problems. This research was supported by the Institute for Collaborative Biotechnologies through grant W911NF-09-0001 from the U.S. Army Research Office.

  8. Magmatic Systems in 3-D

    NASA Astrophysics Data System (ADS)

    Kent, G. M.; Harding, A. J.; Babcock, J. M.; Orcutt, J. A.; Bazin, S.; Singh, S.; Detrick, R. S.; Canales, J. P.; Carbotte, S. M.; Diebold, J.

    2002-12-01

    Multichannel seismic (MCS) images of crustal magma chambers are ideal targets for advanced visualization techniques. In the mid-ocean ridge environment, reflections originating at the melt-lens are well separated from other reflection boundaries, such as the seafloor, layer 2A and Moho, which enables the effective use of transparency filters. 3-D visualization of seismic reflectivity falls into two broad categories: volume and surface rendering. Volumetric-based visualization is an extremely powerful approach for the rapid exploration of very dense 3-D datasets. These 3-D datasets are divided into volume elements or voxels, which are individually color coded depending on the assigned datum value; the user can define an opacity filter to reject plotting certain voxels. This transparency allows t