Laboratory study of forced rotating shallow water turbulence

NASA Astrophysics Data System (ADS)

Espa, Stefania; Di Nitto, Gabriella; Cenedese, Antonio

2011-12-01

During the last three decades several authors have studied the appearance of multiple zonal jets in planetary atmospheres and in the Earths oceans. The appearance of zonal jets has been recovered in numerical simulations (Yoden & Yamada, 1993), laboratory experiments (Afanasyev & Wells, 2005; Espa et al., 2008, 2010) and in field measurements of the atmosphere of giant planets (Galperin et al., 2001). Recent studies have revealed the presence of zonation also in the Earths oceans, in fact zonal jets have been found in the outputs of Oceanic General Circulation Models-GCMs (Nakano & Hasumi, 2005) and from the analysis of satellite altimetry observations (Maximenko et al., 2005). In previous works (Espa et al., 2008, 2010) we have investigated the impact of the variation of the rotation rate and of the fluid depth on jets organization in decaying and forced regimes. In this work we show results from experiments performed in a bigger domain in which the fluid is forced continuously. The experimental set-up consists of a rotating tank (1m in diameter) where the initial distribution of vorticity has been generated via the Lorentz force in an electromagnetic cell. The latitudinal variation of the Coriolis parameter has been simulated by the parabolic profile assumed by the free surface of the rotating fluid. Flow measurements have been performed using an image analysis technique. Experiments have been performed changing the tank rotation rate and the fluid thickness. We have investigated the flow in terms of zonal and radial flow pattern, flow variability and jet scales.

Emergence and equilibration of jets in planetary turbulence

NASA Astrophysics Data System (ADS)

Constantinou, Navid; Ioannou, Petros; Farrell, Brian

2013-04-01

Spatially and temporally coherent large scale jets that are not forced directly at the jet scale are prominent feature of rotating turbulence. A familiar example is the midlatitude jet in the Earth's atmosphere and the banded winds of the giants planets. These jets arise and are supported by the systematic organisation of the turbulent Reynolds stresses. Understanding the mechanism producing the required eddy momentum flux convergence, and how the jets and associated eddy field mutually adjust to maintain a steady jet structure at finite amplitude, constitute fundamental theoretical problems. Stochastic Structural Stability Theory (SSST) gives an explanation for jet formation that is fundamentally based on the interaction between jets and their associated field of turbulent eddies. SSST combines the full dynamics of the zonal mean flow with the second order statistics of the turbulent field obtained from a stochastic turbulence model (STM). The quasi-linear (QL) approximation to the full nonlinear dynamics (NL) results when the perturbation-perturbation interactions are parameterized in the perturbation equations, while interaction between the perturbations and the zonal mean flow is retained in the zonal mean equation. SSST consists of an infinite ensemble of perturbations evolving under QL. Therefore, SSST provides a set of dynamical equations for the mean flow and the second order statistics of the second cummulant of the perturbation vorticity field, which are autonomous and fluctuation free and can facilitate analytic study of turbulent equilibria and their stability as a function of parameters. Thus, jet formation in homogeneous beta-turbulence can be identified with an SSST structural instability of a homogeneous (mean flow free) SSTT equilibrium. We investigate the emergence and equilibration of jets from homogeneous barotropic beta-plane turbulence in the absence of coherent external forcing. SSST predicts that infinitesimal perturbations with zonal jet form organise homogeneous turbulence to produce systematic upgradient fluxes, giving rise to exponential jet growth and eventually to the establishment of finite amplitude equilibrium jets. We compare these predictions with simulations of the NL equations and their QL approximation in order to examine further the mechanism of emergence and equilibration of jets from turbulence. We concentrate on the effects of perturbation-perturbation nonlinearity on jet bifurcation and equilibration, and on the influence of perturbations in exciting the manifold of SSST modes with jet structure. We find that the bifurcation structure predicted by SSST for the emergence of zonal jets from a homogeneous turbulent state is confirmed by both QL and NL simulations. Moreover, we show that the finite amplitude equilibrium jets found in NL and QL simulations are as predicted by the fixed point solutions of SSST. Obtaining this agreement between NL and both SSST and QL simulations required in some cases that the modification of the turbulent spectrum caused by the perturbation-perturbation nonlinearity in NL be accounted for in the specification of the stochastic forcing in QL and SSST. These results confirm that jet emergence in barotropic beta-plane turbulence can be traced to the cooperative mean flow/perturbation instability that is captured by SSST.

Frequency-dependent behavior of the barotropic and baroclinic modes of zonal jet variability

NASA Astrophysics Data System (ADS)

Sheshadri, A.; Plumb, R. A.

2016-12-01

Stratosphere-troposphere interactions are frequently described in terms of the leading modes of variability, i.e. the annular modes. An idealized dynamical core model is used to explore the differences between the low- and high- frequency (periods greater and less than 30 days) behavior of the first two principal components of zonal mean zonal wind and eddy kinetic energy, i.e., the barotropic/baroclinic annular modes of variability of the extratropical circulation. The modes show similar spatial characteristics in the different frequency ranges considered, however the ranking of the modes switches in some cases from one range to the other. There is some cancelation in the signatures of eddy heat flux and eddy kinetic energy in the leading low-pass and high-pass filtered zonal wind mode, partly explaining their small signature in the total. At low frequencies, the first zonal wind mode describes latitudinal shifts of both the midlatitude jet and its associated storm tracks, and the persistence of zonal wind anomalies appears to be sustained primarily by a baroclinic, rather than a barotropic, feedback. On shorter time scales, the behavior is more complicated and transient.

Transport in zonal flows in analogous geophysical and plasma systems

NASA Astrophysics Data System (ADS)

del-Castillo-Negrete, Diego

1999-11-01

Zonal flows occur naturally in the oceans and the atmosphere of planets. Important examples include the zonal flows in Jupiter, the stratospheric polar jet in Antarctica, and oceanic jets like the Gulf Stream. These zonal flows create transport barriers that have a crucial influence on mixing and confinement (e.g. the ozone depletion in Antarctica). Zonal flows also give rise to long-lasting vortices (e.g. the Jupiter red spot) by shear instability. Because of this, the formation and stability of zonal flows and their role on transport have been problems of great interest in geophysical fluid dynamics. On the other hand, zonal flows have also been observed in fusion plasmas and their impact on the reduction of transport has been widely recognized. Based on the well-known analogy between Rossby waves in quasigeostrophic flows and drift waves in magnetically confined plasmas, I will discuss the relevance to fusion plasmas of models and experiments recently developed in geophysical fluid dynamics. Also, the potential application of plasma physics ideas to geophysical flows will be discussed. The role of shear in the suppression of transport and the effect of zonal flows on the statistics of transport will be studied using simplified models. It will be shown how zonal flows induce large particle displacements that can be characterized as Lévy flights, and that the trapping effect of vortices combined with the zonal flows gives rise to anomalous diffusion and Lévy (non-Gaussian) statistics. The models will be compared with laboratory experiments and with atmospheric and oceanographic qualitative observations.

Investigations of the preferred modes of north Pacific jet variability, their downstream impacts, and tropical and extratropical precursors

NASA Astrophysics Data System (ADS)

Griffin, Kyle S.

Time extended EOF (TE-EOF) analysis is employed to examine the synoptic-scale evolution of the two leading modes of north Pacific jet stream variability, namely its zonal extension/retraction (TE-EOF 1) and the north/south shift of its exit region (TE-EOF 2). Composite analyses are constructed preceding and following peaks in the principal component associated with each of the two TE-EOFs, providing insight into the preferred evolutions of the north Pacific jet. Jet extension events are associated with an anomalous Gulf of Alaska cyclone, while jet retractions are associated with an anomalous ridge over the Aleutians. Similar but shifted upper level patterns are noted with the corresponding poleward/equatorward shifted jet phases, with the poleward (equatorward) shift of the jet exit region associated with anomalous low-level warmth (cold) over western North America. Such composites also suggest connections between certain phases of these leading modes of jet variability and deep convection in the tropics, a connection that has been challenging to physically diagnose in previous studies. The isentropic pressure depth measures the mass contained within an isentropic layer in a given grid column, enabling the tracking of mass exhausted by deep convection. The gradient of isentropic pressure depth is directly associated with the vertical geostrophic wind shear in that layer and thus provides a means to track the influence of convective mass flux on the evolution of the jet stream. A case study focused on the extreme North American warm episode of March 2012 demonstrates how positive pressure depth anomalies from a strong MJO event impact the jet stream over eastern Asia and drive a portion of the mid-latitude response that leads to the flow amplification and subsequent downstream warmth. This study demonstrates one way by which isentropic pressure depth can diagnose the impacts of tropical deep convection on the mid-latitude circulation. Using TE-EOFs, composites of isentropic pressure depth are constructed, to examine the evolution of pressure depth anomalies preceding each phase of the two leading modes of jet variability. In jet extension events, a large negative pressure depth anomaly in the 315-330 K isentropic layer and a positive pressure depth anomaly in the 340-355 K isentropic layer align north and south of the climatological jet exit region, respectively. A similar but opposite configuration is found in jet retraction events. During poleward shifted jet events, the configuration of pressure depth anomalies is comparable to that observed in jet extension events, but shifted poleward. Positive pressure depth anomalies in each set of events predominantly originate from either the Maritime Continent or East Asia and track along the climatological jet before impacting the exit region of the jet stream. Negative pressure depth anomalies have similar upstream origins before moving through the jet in a similar manner. These composite evolutions provide insight into the synoptic-scale evolutions that precede the preferred modes of jet variability, highlighting the influence of both mid-latitude weather systems and mass flux from tropical deep convection on North Pacific jet variability.

Model test of anchoring effect on zonal disintegration in deep surrounding rock masses.

PubMed

Chen, Xu-Guang; Zhang, Qiang-Yong; Wang, Yuan; Liu, De-Jun; Zhang, Ning

2013-01-01

The deep rock masses show a different mechanical behavior compared with the shallow rock masses. They are classified into alternating fractured and intact zones during the excavation, which is known as zonal disintegration. Such phenomenon is a great disaster and will induce the different excavation and anchoring methodology. In this study, a 3D geomechanics model test was conducted to research the anchoring effect of zonal disintegration. The model was constructed with anchoring in a half and nonanchoring in the other half, to compare with each other. The optical extensometer and optical sensor were adopted to measure the displacement and strain changing law in the model test. The displacement laws of the deep surrounding rocks were obtained and found to be nonmonotonic versus the distance to the periphery. Zonal disintegration occurs in the area without anchoring and did not occur in the model under anchoring condition. By contrasting the phenomenon, the anchor effect of restraining zonal disintegration was revealed. And the formation condition of zonal disintegration was decided. In the procedure of tunnel excavation, the anchor strain was found to be alternation in tension and compression. It indicates that anchor will show the nonmonotonic law during suppressing the zonal disintegration.

Model Test of Anchoring Effect on Zonal Disintegration in Deep Surrounding Rock Masses

PubMed Central

Chen, Xu-Guang; Zhang, Qiang-Yong; Wang, Yuan; Liu, De-Jun; Zhang, Ning

2013-01-01

The deep rock masses show a different mechanical behavior compared with the shallow rock masses. They are classified into alternating fractured and intact zones during the excavation, which is known as zonal disintegration. Such phenomenon is a great disaster and will induce the different excavation and anchoring methodology. In this study, a 3D geomechanics model test was conducted to research the anchoring effect of zonal disintegration. The model was constructed with anchoring in a half and nonanchoring in the other half, to compare with each other. The optical extensometer and optical sensor were adopted to measure the displacement and strain changing law in the model test. The displacement laws of the deep surrounding rocks were obtained and found to be nonmonotonic versus the distance to the periphery. Zonal disintegration occurs in the area without anchoring and did not occur in the model under anchoring condition. By contrasting the phenomenon, the anchor effect of restraining zonal disintegration was revealed. And the formation condition of zonal disintegration was decided. In the procedure of tunnel excavation, the anchor strain was found to be alternation in tension and compression. It indicates that anchor will show the nonmonotonic law during suppressing the zonal disintegration. PMID:23997683

Structure of the Mesosphere of Venus from the reanalized Venera 15 IR-spectrometry data

NASA Astrophysics Data System (ADS)

Zasova, L. V.; Moroz, V. I.; Ignatiev, N. I.; Khatountsev, I. V.

1998-09-01

The results of IR-spectromerty on board VENERA-15 have been reanalyzed. The new data concerned temperature, aerosol, water vapor and thermal zonal wind profiles have been obtained and the latitudinal and local time related variations have been investigated. The cyclostrophic zonal wind fields show the presence of mid-latitudinal jet which changes its position with solar time, so that its altitude and wind speed are correlated and indicated the conservation of angular momentum. The connection between altitude of jet and its velocity shows the flux conservation. The wind velocity in the midlatitudinal jet is correlated with temperature inversion in the "cold collar". The low-latitudinal jet (at about 80 km near 20 deg.) is also connected with inversion in temperature profile observed there.

Thermal shallow water models of geostrophic turbulence in Jovian atmospheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warneford, Emma S., E-mail: emma.warneford@maths.ox.ac.uk; Dellar, Paul J., E-mail: dellar@maths.ox.ac.uk

2014-01-15

Conventional shallow water theory successfully reproduces many key features of the Jovian atmosphere: a mixture of coherent vortices and stable, large-scale, zonal jets whose amplitude decreases with distance from the equator. However, both freely decaying and forced-dissipative simulations of the shallow water equations in Jovian parameter regimes invariably yield retrograde equatorial jets, while Jupiter itself has a strong prograde equatorial jet. Simulations by Scott and Polvani [“Equatorial superrotation in shallow atmospheres,” Geophys. Res. Lett. 35, L24202 (2008)] have produced prograde equatorial jets through the addition of a model for radiative relaxation in the shallow water height equation. However, their modelmore » does not conserve mass or momentum in the active layer, and produces mid-latitude jets much weaker than the equatorial jet. We present the thermal shallow water equations as an alternative model for Jovian atmospheres. These equations permit horizontal variations in the thermodynamic properties of the fluid within the active layer. We incorporate a radiative relaxation term in the separate temperature equation, leaving the mass and momentum conservation equations untouched. Simulations of this model in the Jovian regime yield a strong prograde equatorial jet, and larger amplitude mid-latitude jets than the Scott and Polvani model. For both models, the slope of the non-zonal energy spectra is consistent with the classic Kolmogorov scaling, and the slope of the zonal energy spectra is consistent with the much steeper spectrum observed for Jupiter. We also perform simulations of the thermal shallow water equations for Neptunian parameter values, with a radiative relaxation time scale calculated for the same 25 mbar pressure level we used for Jupiter. These Neptunian simulations reproduce the broad, retrograde equatorial jet and prograde mid-latitude jets seen in observations. The much longer radiative time scale for the colder planet Neptune explains the transition from a prograde to a retrograde equatorial jet, while the broader jets are due to the deformation radius being a larger fraction of the planetary radius.« less

Deep Zonal Flow and Time Variation of Jupiter’s Magnetic Field

NASA Astrophysics Data System (ADS)

Cao, Hao; Stevenson, David J.

2017-10-01

All four giant planets in the Solar System feature zonal flows on the order of 100 m/s in the cloud deck, and large-scale intrinsic magnetic fields on the order of 1 Gauss near the surface. The vertical structure of the zonal flows remains obscure. The end-member scenarios are shallow flows confined in the radiative atmosphere and deep flows throughout the entire planet. The electrical conductivity increases rapidly yet smoothly as a function of depth inside Jupiter and Saturn. Deep zonal flows will advect the non-axisymmetric component of the magnetic field, at depth with even modest electrical conductivity, and create time variations in the magnetic field.The observed time variations of the geomagnetic field has been used to derive surface flows of the Earth’s outer core. The same principle applies to Jupiter, however, the connection between the time variation of the magnetic field (dB/dt) and deep zonal flow (Uphi) at Jupiter is not well understood due to strong radial variation of electrical conductivity. Here we perform a quantitative analysis of the connection between dB/dt and Uphi for Jupiter adopting realistic interior electrical conductivity profile, taking the likely presence of alkali metals into account. This provides a tool to translate expected measurement of the time variation of Jupiter’s magnetic field to deep zonal flows. We show that the current upper limit on the dipole drift rate of Jupiter (3 degrees per 20 years) is compatible with 10 m/s zonal flows with < 500 km vertical scale height below 0.972 Rj. We further demonstrate that fast drift of resolved magnetic features (e.g. magnetic spots) at Jupiter is a possibility.

A Zonal Approach for Prediction of Jet Noise

NASA Technical Reports Server (NTRS)

Shih, S. H.; Hixon, D. R.; Mankbadi, Reda R.

1995-01-01

A zonal approach for direct computation of sound generation and propagation from a supersonic jet is investigated. The present work splits the computational domain into a nonlinear, acoustic-source regime and a linear acoustic wave propagation regime. In the nonlinear regime, the unsteady flow is governed by the large-scale equations, which are the filtered compressible Navier-Stokes equations. In the linear acoustic regime, the sound wave propagation is described by the linearized Euler equations. Computational results are presented for a supersonic jet at M = 2. 1. It is demonstrated that no spurious modes are generated in the matching region and the computational expense is reduced substantially as opposed to fully large-scale simulation.

Propagating and Non-propagating Annular Modes and Principal Oscillation Patterns

NASA Astrophysics Data System (ADS)

Plumb, R. A.; Sheshadri, A.

2016-12-01

The leading "annular mode" in each hemisphere — usually defined as the dominant EOF of surface pressure or of zonal mean zonal wind variability — appears as a dipolar structure straddling the mean midlatitude jet and thus seems to describe north-south wobbling of the jet latitude. However, extratropical zonal wind anomalies frequently tend to migrate poleward. This behavior can be described by the first two EOFs, the first (AM1) being the dipolar structure, and the second (AM2) having a tripolar structure centered on the mean jet. (AM2 explains a significant amount of variance, though less than AM1.) Taken in isolation, AM1 thus describes a north-south wobbling of the jet position, while AM2 describes a strengthening and narrowing (or weakening and broadening) of the jet. However, despite the fact that they are spatially orthogonal, and their corresponding time series temporally orthogonal, AM1 and AM2 are not independent, but show significant lag-correlations which reveal the poleward propagation. The EOFs are not modes of the underlying dynamical system governing the zonal flow evolution. The true modes can be estimated using principal oscillation pattern (POP) analysis. The leading POPs manifest themselves as a pair of complex conjugate structures with conjugate eigenvalues thus, in reality, constituting a single, complex, mode that describes poleward propagating anomalies. This mode then shows up as AM1 and AM2 in EOF analyses. Even though the principal components associated with the two leading EOFs decay at different rates, each decays faster than the true mode. In the propagating regime, these facts have implications for the use of autocorrelations and cross-correlations to quantify eddy feedback and the susceptibility of the mode to external perturbations, including the response to stratospheric anomalies.

Gravity Waves in the Presence of Shear during DEEPWAVE

NASA Astrophysics Data System (ADS)

Doyle, J. D.; Jiang, Q.; Reinecke, P. A.; Reynolds, C. A.; Eckermann, S. D.; Fritts, D. C.; Smith, R. B.; Taylor, M. J.; Dörnbrack, A.

2016-12-01

The DEEP propagating gravity WAVE program (DEEPWAVE) is a comprehensive, airborne and ground-based measurement and modeling program centered on New Zealand and focused on providing a new understanding of gravity wave dynamics and impacts from the troposphere through the mesosphere and lower thermosphere. This program employed the NSF/NCAR GV (NGV) research aircraft from a base in New Zealand in a 6-week field measurement campaign in June-July 2014. During the field phase, the NGV was equipped with new Rayleigh and sodium resonance lidars and an advanced mesospheric temperature mapper (AMTM), a microwave temperature profiler (MTP), as well as dropwindsondes and flight level instruments providing measurements spanning altitudes from immediately above the NGV flight altitude ( 13 km) to 100 km. In this study, we utilize the DEEPWAVE observations and the nonhydrostatic COAMPS configured at high resolution (2 km) with a deep domain (60-80 km) to explore the effects of horizontal wind shear on gravity wave propagation and wave characteristics. Real-data simulations have been conducted for several DEEPWAVE cases. The results suggest that horizontal shear associated with the stratospheric polar night jet refracts the gravity waves and leads to propagation of waves significantly downwind of the South Island. These waves have been referred to as "trailing gravity waves", since they are found predominantly downwind of the orography of the South Island and the wave crests rotate nearly normal to the mountain crest. Observations from the G-V, remote sensing instruments, and the AIRS satellite confirm the presence of gravity waves downwind of the orography in numerous events. The horizontal propagation in the stratosphere can be explained by group velocity arguments for gravity waves in which the wave energy is advected downwind by the component of the flow normal to the horizontal wavevector. We explore the impact of the shear on gravity wave propagation in COAMPS configured in an idealized mode initialized with a zonally balanced stratospheric jet. The idealized results confirm the importance of horizontal wind shear for the refraction of the waves. The zonal momentum flux minimum is shown to bend or refract into the jet in the stratosphere as a consequence of the wind shear.

Cloud motions on Venus - Global structure and organization

NASA Technical Reports Server (NTRS)

Limaye, S. S.; Suomi, V. E.

1981-01-01

Results on cloud motions on Venus obtained over a period of 3.5 days from Mariner 10 television images are presented. The implied atmosphere flow is almost zonal everywhere on the visible disk, and is in the same retrograde sense as the solid planet. Objective analysis of motions suggests the presence of jet cores (-130 m/s) and organized atmospheric waves. The longitudinal mean meridional profile of the zonal component of motion of the ultraviolet features shows presence of a midlatitude jet stream (-110 m/s). The mean zonal component is -97 m/s at the equator. The mean meridional motion at most latitudes is directed toward the pole in either hemisphere and is at least an order of magnitude smaller so that the flow is nearly zonal. A tentative conclusion from the limited coverage available from Mariner 10 is that at the level of ultraviolet features mean meridional circulation is the dominant mode of poleward angular momentum transfer as opposed to the eddy circulation.

Some observed seasonal changes in extratropical general circulation: A study in terms of vorticity. [seasonal migrations of extra tropical frontal jet streams

NASA Technical Reports Server (NTRS)

Srivatsangam, S.; Reiter, E. R.

1973-01-01

Extratropical eddy distributions in four months typical of the four seasons are treated in terms of temporal mean and temporal r.m.s. values of the geostrophic relative vorticity. The geographical distributions of these parameters at the 300 mb level show that the arithmetic mean fields are highly biased representatives of the extratropical eddy distributions. The zonal arithmetic means of these parameters are also presented. These show that the zonal-and-time mean relative vorticity is but a small fraction of the zonal mean of the temporal r.m.s. relative vorticity, K. The reasons for considering the r.m.s. values as the temporal normal values of vorticity in the extratropics are given in considerable detail. The parameter K is shown to be of considerable importance in locating the extratropical frontal jet streams (EFJ) in time-and-zonal average distributions. The study leads to an understanding of the seasonal migrations of the EFJ which have not been explored until now.

Zonostrophic turbulence

NASA Astrophysics Data System (ADS)

Galperin, Boris; Sukoriansky, Semion; Dikovskaya, Nadejda

2008-12-01

Geostrophic turbulence is a flow regime attained by turbulent, rotating, stably stratified fluids in near-geostrophic balance. When a small-scale forcing is present, flows in this regime may develop an inverse energy cascade. Geostrophic turbulence has been used in geophysical fluid dynamics as a relatively simple model of the large-scale planetary and terrestrial circulations. When the meridional variation of the Coriolis parameter (or a β-effect) is taken into account, the horizontal flow symmetry breaks down giving rise to the emergence of jet flows. In a certain parameter range, a new flow regime comes to life. Its main characteristics include strongly anisotropic kinetic energy spectrum and slowly evolving systems of alternating zonal jets. This regime is a subset of geostrophic turbulence and has been coined zonostrophic turbulence; it can develop both on a β-plane and on the surface of a rotating sphere. This regime was first discovered in computer simulations but later revealed in the laboratory experiments, in the deep terrestrial oceans, and on solar giant planets where it is believed to be the primary physical mechanism responsible for the generation and maintenance of the stable systems of alternating zonal jets. The hallmarks of zonostrophic turbulence are the anisotropic inverse energy cascade and complicated interaction between turbulence and Rossby-Haurwitz waves. Addressing the goals of the conference 'Turbulent Mixing and Beyond' that took place in August 2007 in Trieste, Italy, this paper exposes the regime of zonostrophic turbulence to a wide scientific community, provides a survey of this regime, elaborates its main characteristics, offers novel approaches to describe and understand this phenomenon, and discusses its applicability as a model of the large-scale planetary and terrestrial circulations.

Rossby waves and two-dimensional turbulence in a large-scale zonal jet

NASA Technical Reports Server (NTRS)

Shepherd, Theodor G.

1987-01-01

Homogeneous barotropic beta-plane turbulence is investigated, taking into account the effects of spatial inhomogeneity in the form of a zonal shear flows. Attention is given to the case of zonal flows that are barotropically stable and of larger scale than the resulting transient eddy field. Numerical simulations reveal that large-scale zonal flows alter the picture of classical beta-plane turbulence. It is found that the disturbance field penetrates to the largest scales of motion, that the larger disturbance scales show a tendency to meridional rather than zonal anisotropy, and that the initial spectral transfer rate away from an isotropic intermediate-scale source is enhanced by the shear-induced transfer associated with straining by the zonal flow.

Effects of Bulk Composition on the Atmospheric Dynamics on Close-in Exoplanets

NASA Astrophysics Data System (ADS)

Zhang, Xi; Showman, Adam P.

2017-02-01

Super Earths and mini Neptunes likely have a wide range of atmospheric compositions, ranging from low molecular mass atmospheres of H2 to higher molecular atmospheres of water, CO2, N2, or other species. Here we systematically investigate the effects of atmospheric bulk compositions on temperature and wind distributions for tidally locked sub-Jupiter-sized planets, using an idealized 3D general circulation model (GCM). The bulk composition effects are characterized in the framework of two independent variables: molecular weight and molar heat capacity. The effect of molecular weight dominates. As the molecular weight increases, the atmosphere tends to have a larger day-night temperature contrast, a smaller eastward phase shift in the thermal phase curve, and a smaller zonal wind speed. The width of the equatorial super-rotating jet also becomes narrower, and the “jet core” region, where the zonal-mean jet speed maximizes, moves to a greater pressure level. The zonal-mean zonal wind is more prone to exhibit a latitudinally alternating pattern in a higher molecular weight atmosphere. We also present analytical theories that quantitatively explain the above trends and shed light on the underlying dynamical mechanisms. Those trends might be used to indirectly determine the atmospheric compositions on tidally locked sub-Jupiter-sized planets. The effects of the molar heat capacity are generally small. But if the vertical temperature profile is close to adiabatic, molar heat capacity will play a significant role in controlling the transition from a divergent flow in the upper atmosphere to a jet-dominated flow in the lower atmosphere.

Zonal flow as pattern formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parker, Jeffrey B.; Krommes, John A.

2013-10-15

Zonal flows are well known to arise spontaneously out of turbulence. We show that for statistically averaged equations of the stochastically forced generalized Hasegawa-Mima model, steady-state zonal flows, and inhomogeneous turbulence fit into the framework of pattern formation. There are many implications. First, the wavelength of the zonal flows is not unique. Indeed, in an idealized, infinite system, any wavelength within a certain continuous band corresponds to a solution. Second, of these wavelengths, only those within a smaller subband are linearly stable. Unstable wavelengths must evolve to reach a stable wavelength; this process manifests as merging jets.

Jets and Water Clouds on Jupiter

NASA Astrophysics Data System (ADS)

Lian, Yuan; Showman, A. P.

2012-10-01

Ground-based and spacecraft observations show that Jupiter exhibits multiple banded zonal jet structures. These banded jets correlate with dark and bright clouds, often called "belts" and "zones". The mechanisms that produce these banded zonal jets and clouds are poorly understood. Our previous studies showed that the latent heat released by condensation of water vapor could produce equatorial superrotation along with multiple zonal jets in the mid-to-high latitudes. However, that previous work assumed complete and instant removal of condensate and therefore could not predict the cloud formation. Here we present an improved 3D Jupiter model to investigate some effects of cloud microphysics on large-scale dynamics using a closed water cycle that includes condensation, three-dimensional advection of cloud material by the large-scale circulation, evaporation and sedimentation. We use a dry convective adjustment scheme to adjust the temperature towards a dry adiabat when atmospheric columns become convectively unstable, and the tracers are mixed within the unstable layers accordingly. Other physics parameterizations included in our model are the bottom drag and internal heat flux as well as the choices of either Newtonian heating scheme or gray radiative transfer. Given the poorly understood cloud microphysics, we perform case studies by treating the particle size and condensation/evaporation time scale as free parameters. We find that, in some cases, the active water cycle can produce multiple banded jets and clouds. However, the equatorial jet is generally very weak in all the cases because of insufficient supply of eastward eddy momentum fluxes. These differences may result from differences in the overall vertical stratification, baroclinicity, and moisture distribution in our new models relative to the older ones; we expect to elucidate the dynamical mechanisms in continuing work.

Ground-based observations of the long-term evolution and death of Saturn's 2010 Great White Spot

NASA Astrophysics Data System (ADS)

Sánchez-Lavega, Agustín; del Río-Gaztelurrutia, Teresa; Delcroix, Marc; Legarreta, Jon J.; Gómez-Forrellad, Josep M.; Hueso, Ricardo; García-Melendo, Enrique; Pérez-Hoyos, Santiago; Barrado-Navascués, David; Lillo, Jorge; International Outer Planet Watch Team IOPW-PVOL

2012-08-01

We report on the long-term evolution of Saturn's sixth Great White Spot (GWS) event that initiated at northern mid-latitudes of the planet on December 5th, 2010 (Fletcher, L. et al. [2011]. Science 332, 1413-1417; Sánchez-Lavega, A. et al. [2011]. Nature 475, 71-74; Fischer, G. et al. [2011]. Nature 475, 75-77). We find from ground-based observations that the GWS formed a planetary-scale disturbance that encircled the planet in 50 days, covering the latitude band between 24.6° and 44.8°N (planetographic) or about 22,000 km in meridional extent and 280,000 km in full zonal circumference length. The head of the GWS was located at an averaged latitude of 40.8 ± 1°N in the peak of a westward jet and showed a mean linear drift in System III longitude of 2.793 deg/day, equivalent to a mean zonal velocity of u = -27.9 m s-1, with maximum speed fluctuations around this mean of -5.3 to +2.7 m s-1. The difference between the undisturbed jet peak velocity and the GWS head was Δu = -12 m s-1. Assuming the GWS has a deep origin at the water cloud a vertical extent of Δz ˜ 250 km is expected and we can derive a vertical shear of the zonal winds ∂u/∂z ˜ 5 × 10-5 s-1. The cloud morphology of the disturbance was sculpted by the winds at this latitude and their latitudinal shears, showing several distinct features: (1) A long-lived Dark Spot (DS, anticyclone vortex) placed at 41.5 ± 1.1°N with a speed u = -11.0 ± 0.1 m s-1 and a size of 7800 km (East-West) per 6000 km (North-South). (2) Two branches of zonally periodic features at both sides of the jet peak, a northern branch at 44.4°N (anticyclonic) and a southern branch at 32°N (cyclonic), with wavelengths in the range ˜ 5000-14,000 km. Precise long-term cloud tracking of disturbance features shows that they moved with speeds close to those of the prevailing winds, although differences up to ˜-45 m s-1 were measured, probably due to wave motion or to real wind changes produced by momentum transfers induced by the disturbance. Vortex DS and the GWS head encountered between the 15th and 19th of June 2011, disappearing within the resolution of our images. We present and discuss two simple hypothesis to explain the nature of this phenomenon. Taking into account our results together with previous historical events, we summarize the mysteries of GWS phenomena: seasonal forcing, occurrence at preferred latitudes only in the Northern hemisphere, no relation of the outbreaks with the wind profile structure and the existence of a continuous deep moist convection source to feed the disturbance.

The 10-30-day oscillation of winter zonal wind in the entrance region of the East Asian subtropical jet and its relationship with precipitation in southern China

NASA Astrophysics Data System (ADS)

Yao, Chenyu; Huang, Qian; Zhu, Bin; Liu, Fei

2018-06-01

Using ECMWF ERA-Interim 6-h reanalysis data, zonal wind intra-seasonal oscillations (ISOs) in the entrance region of the East Asian subtropical westerly jet (EASWJ) in winter from 1979/1980 to 2012/2013 are studied. The results first show that there is an area with large ISO strength in the northwest of the EASWJ; in the key region, zonal wind has a dominant period of 10-30 days. The composite analysis reveals that zonal wind at 200 hPa in this key region has 10-30-day oscillation characteristics. On the 10-30-day time scale, the center of zonal wind anomaly moves eastward. The propagation of zonal wind oscillation relates to temperature tendencies at different latitudes. The remarkable increase (or decrease) in zonal wind in the key region is mostly determined by temperature anomalies to the north. The 10-30-day filtered temperature advection to the north of the key region leads to either a decrease or an increase in temperature; on the other hand, temperature variations south of the key region have trends opposite of the northern trends, which changes the temperature gradient. On the 10-30-day time scale, zonal wind anomalies are associated with precipitation in southern China. When there are easterly wind anomalies over the key region, precipitation occurs over the Yangtze River basin and its south. Diabatic heating during precipitation corresponds with warming to the south of the key region, which combines with the temperature advection to weaken the easterly wind and strengths the westerly wind. Then, the intra-seasonal precipitation moves to southwest China with warm advection and the enhanced westerly wind, which brings the positive relative vorticity advection there.

A zonal method for modeling powered-lift aircraft flow fields

NASA Technical Reports Server (NTRS)

Roberts, D. W.

1989-01-01

A zonal method for modeling powered-lift aircraft flow fields is based on the coupling of a three-dimensional Navier-Stokes code to a potential flow code. By minimizing the extent of the viscous Navier-Stokes zones the zonal method can be a cost effective flow analysis tool. The successful coupling of the zonal solutions provides the viscous/inviscid interations that are necessary to achieve convergent and unique overall solutions. The feasibility of coupling the two vastly different codes is demonstrated. The interzone boundaries were overlapped to facilitate the passing of boundary condition information between the codes. Routines were developed to extract the normal velocity boundary conditions for the potential flow zone from the viscous zone solution. Similarly, the velocity vector direction along with the total conditions were obtained from the potential flow solution to provide boundary conditions for the Navier-Stokes solution. Studies were conducted to determine the influence of the overlap of the interzone boundaries and the convergence of the zonal solutions on the convergence of the overall solution. The zonal method was applied to a jet impingement problem to model the suckdown effect that results from the entrainment of the inviscid zone flow by the viscous zone jet. The resultant potential flow solution created a lower pressure on the base of the vehicle which produces the suckdown load. The feasibility of the zonal method was demonstrated. By enhancing the Navier-Stokes code for powered-lift flow fields and optimizing the convergence of the coupled analysis a practical flow analysis tool will result.

Thermal zonal winds in the Venus mesosphere from the Venus Express temperature soundings

NASA Astrophysics Data System (ADS)

Piccialli, Arianna; Titov, Dmitri; Tellmann, Silvia; Migliorini, Alessandra; Read, Peter; Grassi, Davide; Paetzold, Martin; Haeusler, Bernd; Piccioni, Giuseppe; Drossart, Pierre

The Venus mesosphere (60-100 km altitude) is a transition region characterized by extremely complex dynamics: strong retrograde zonal winds dominate in the troposphere and lower meso-sphere while a solar-antisolar circulation can be observed in the upper mesosphere. The super-rotation extends from the surface up to the cloud top (˜65 km altitude) with wind speeds of only a few meters per second near the surface and reaching a maximum value of ˜100 m s-1 at cloud top, corresponding to a rotation period of ˜4 Earth days (˜60 times faster than Venus itself). The solar-antisolar circulation is driven by the day-night contrast in solar heating, and occurs above 110 km altitude with speeds of 120 m s-1 . The processes responsible for maintain-ing the zonal super-rotation in the lower atmosphere and its transition to the solar-antisolar circulation in the upper atmosphere are still poorly understood (Schubert et al.,2007). Different techniques have been used to obtain direct observations of wind at various altitudes: tracking of clouds in ultraviolet (UV) and near infrared (NIR) images give information on wind speeds at the cloud top (Moissl et al., 2009; Sanchez-Lavega et al., 2008) and within the clouds (˜47 km, ˜61 km) (Sanchez-Lavega et al., 2008) while ground-based measurements of Doppler shifts in the CO2 band at 10 µm (Sornig et al., 2008) and in several CO millimiter lines (Rengel et al., 2008) provide wind speeds above the clouds up to ˜110 km altitude. The deep atmosphere from the surface up to the cloud top has been investigated through the Doppler tracking of descent probes and balloons (Counselman et al., 1980; Kerzhanovich and Limaye, 1985). In the mesosphere, between 45-85 km of altitude, where direct observations of wind are not possible, the zonal wind field can be derived from the vertical temperature structure using a special approximation of the thermal wind equation: based on cyclostrophic balance. Previous studies (Leovy, 1973; Newman et al., 1984) showed that on a slowly rotating planet, like Venus, strong zonal winds at the cloud top can be described by a cyclostrophic balance in which the equatorward component of centrifugal force is balanced by the meridional pressure gradient. This equation gives a possibility to reconstruct the zonal wind if the temperature field is known, together with a suitable boundary condition on u. Two experiments onboard Venus Express are sounding the temperature structure of the Venus mesosphere: VIRTIS sounds the Venus Southern hemisphere in the altitude range 65-90 km with a very good spatial and temporal coverage (Grassi et al., 2008) and the Northern hemi-sphere but with more limited coverage; VeRa observes both northern and southern hemispheres between 40-90 km altitude with a vertical resolution of ˜500 m (Tellmann et al., 2008). Here we present zonal thermal winds derived applying cyclostrophic balance from VIRTIS and VeRa temperature retrievals. The main features of the retrieved winds are: (1) a midlatitude jet with a maximum speed up to 140 ± 15 m s-1 which occurs around 50° S latitude at 70 km altitude; (2) the fast decrease of the wind speed from 60° S toward the pole; (3) the decrease of the wind speed with increasing height above the jet (Piccialli et al., 2008). Cyclostrophic winds show satisfactory agreement with the cloud-tracked winds derived from the Venus Monitoring Camera (VMC/VEx) UV images, although a disagreement is observed at the equator and near the pole due to the breakdown of the cyclostrophic approximation. From zonal thermal winds the Richardson number has been evaluated. In good agreement with previous studies (Allison et al., 1994), we have found that the atmosphere is dominated by convection from ˜45 km altitude up to the cloud top. A high value of Richardson number has been determined, cor-responding to the midlatitude jet and indicating a highly stable atmosphere. Verification of the necessary condition for barotropic instability implies that barotropic instability may occur on the poleward side of the midlatitude jet where planetary waves are expected to play an important role in the maintenance of the circulation.

North Pacific Westerly Jet Influence of the Winter Hawaii Rainfall in the last 21,000 years

NASA Astrophysics Data System (ADS)

Li, S.; Elison Timm, O.

2017-12-01

Hawaii rainfall has a strong seasonality which has more rainfall during the winter than summer. Part of the winter rainfall is from extratropical weather disturbances. Kona lows (KL) are important contributors to the annual rainfall budget of the Hawaiian Islands. KL activity is found to have a strong relationship with the North Pacific climate variability. The goal of the research is to test the hypothesis that changes in the strength and position of the upper level zonal wind jet is a key driver for regional rainfall changes. The main objectives are (1) to identify the relationship between North Pacific westerly jet strength and KL activity in present day climate, (2) to test the stability of this relationship under past climatic conditions, and (3) to explore the teleconnection between Hawaii and North America. For the present-day analysis of the westerly jet, the zonal wind at 250hPa is used from ERA-interim data from 1979-2014. The potential vorticity is used as a measure of extratropical synoptic activity. The Hawaii Rainfall Index is from the Rainfall Atlas of Hawaii (seasonal means, 1920-2012). For the paleoclimatic study, the transient TraCE-21ka simulation is used for the zonal wind - Hawaii rainfall analysis. The results of present-day analysis show that when the jet extends farther into the eastern Pacific sector the Kona Low activity is reduced, less winter rainfall is observed over Hawaii and more rainfall over the California region. The jet position-rainfall relationship was investigated within the TrACE-21 simulation. For the TraCE-21ka dataset, there is an increasing rainfall trend from 21kBP to 14kBP; this period coincides with a gradual decrease in the strength of the westerly wind jet. The results show that the westerly jet strength has a strong influence of the Kona Low activity and the rainfall over Hawaii both in the present and the past.

The Dynamics of Eddy Fluxes and Jet-Scale Overturning Circulations and its Impact on the Mixed Layer Formation in the Indo-Western Pacific Southern Ocean

NASA Astrophysics Data System (ADS)

LI, Q.; Lee, S.

2016-12-01

The relationship between Antarctic Circumpolar Current (ACC) jets and eddy fluxes in the Indo-western Pacific Southern Ocean (90°E-145°E) is investigated using an eddy-resolving model. In this region, transient eddy momentum flux convergence occurs at the latitude of the primary jet core, whereas eddy buoyancy flux is located over a broader region that encompasses the jet and the inter-jet minimum. In a small sector (120°E-144°E) where jets are especially zonal, a spatial and temporal decomposition of the eddy fluxes further reveals that fast eddies act to accelerate the jet with the maximum eddy momentum flux convergence at the jet center, while slow eddies tend to decelerate the zonal current at the inter-jet minimum. Transformed Eulerian mean (TEM) diagnostics reveals that the eddy momentum contribution accelerates the jets at all model depths, whereas the buoyancy flux contribution decelerates the jets at depths below 600 m. In ocean sectors where the jets are relatively well defined, there exist jet-scale overturning circulations (JSOC) with sinking motion on the equatorward flank, and rising motion on the poleward flank of the jets. The location and structure of these thermally indirect circulations suggest that they are driven by the eddy momentum flux convergence, much like the Ferrel cell in the atmosphere. This study also found that the JSOC plays a significant role in the oceanic heat transport and that it also contributes to the formation of a thin band of mixed layer that exists on the equatorward flank of the Indo-western Pacific ACC jets.

Jet formation and equatorial superrotation in Jupiter's atmosphere: Numerical modelling using a new efficient parallel code

NASA Astrophysics Data System (ADS)

Rivier, Leonard Gilles

Using an efficient parallel code solving the primitive equations of atmospheric dynamics, the jet structure of a Jupiter like atmosphere is modeled. In the first part of this thesis, a parallel spectral code solving both the shallow water equations and the multi-level primitive equations of atmospheric dynamics is built. The implementation of this code called BOB is done so that it runs effectively on an inexpensive cluster of workstations. A one dimensional decomposition and transposition method insuring load balancing among processes is used. The Legendre transform is cache-blocked. A "compute on the fly" of the Legendre polynomials used in the spectral method produces a lower memory footprint and enables high resolution runs on relatively small memory machines. Performance studies are done using a cluster of workstations located at the National Center for Atmospheric Research (NCAR). BOB performances are compared to the parallel benchmark code PSTSWM and the dynamical core of NCAR's CCM3.6.6. In both cases, the comparison favors BOB. In the second part of this thesis, the primitive equation version of the code described in part I is used to study the formation of organized zonal jets and equatorial superrotation in a planetary atmosphere where the parameters are chosen to best model the upper atmosphere of Jupiter. Two levels are used in the vertical and only large scale forcing is present. The model is forced towards a baroclinically unstable flow, so that eddies are generated by baroclinic instability. We consider several types of forcing, acting on either the temperature or the momentum field. We show that only under very specific parametric conditions, zonally elongated structures form and persist resembling the jet structure observed near the cloud level top (1 bar) on Jupiter. We also study the effect of an equatorial heat source, meant to be a crude representation of the effect of the deep convective planetary interior onto the outer atmospheric layer. We show that such heat forcing is able to produce strong equatorial superrotating winds, one of the most striking feature of the Jovian circulation.

High-fidelity simulations of unsteady civil aircraft aerodynamics: stakes and perspectives. Application of zonal detached eddy simulation

PubMed Central

Deck, Sébastien; Gand, Fabien; Brunet, Vincent; Ben Khelil, Saloua

2014-01-01

This paper provides an up-to-date survey of the use of zonal detached eddy simulations (ZDES) for unsteady civil aircraft applications as a reflection on the stakes and perspectives of the use of hybrid methods in the framework of industrial aerodynamics. The issue of zonal or non-zonal treatment of turbulent flows for engineering applications is discussed. The ZDES method used in this article and based on a fluid problem-dependent zonalization is briefly presented. Some recent landmark achievements for conditions all over the flight envelope are presented, including low-speed (aeroacoustics of high-lift devices and landing gear), cruising (engine–airframe interactions), propulsive jets and off-design (transonic buffet and dive manoeuvres) applications. The implications of such results and remaining challenges in a more global framework are further discussed. PMID:25024411

Numerical experiments with a general circulation model concerning the stratospheric distribution of ozone

NASA Technical Reports Server (NTRS)

Kurzeja, R. J.; Haggard, K. V.; Grose, W. L.

1981-01-01

Three experiments have been performed using a three-dimensional, spectral quasi-geostrophic model in order to investigate the sensitivity of ozone transport to tropospheric orographic and thermal effects and to the zonal wind distribution. In the first experiment, the ozone distribution averaged over the last 30 days of a 60 day transport simulation was determined; in the second experiment, the transport simulation was repeated, but nonzonal orographic and thermal forcing was omitted; and in the final experiment, the simulation was conducted with the intensity and position of the stratospheric jets altered by addition of a Newtonian cooling term to the zonal-mean diabatic heating rate. Results of the three experiments are summarized by comparing the zonal-mean ozone distribution, the amplitude of eddy geopotential height, the zonal winds, and zonal-mean diabatic heating.

Deep-Water Benthic Foraminifers from the Paleocene and Eocene of the North Pacific Region: Paleontology, Biostratigraphy, and Paleoceanological Reconstructions

NASA Astrophysics Data System (ADS)

Olshanetskiy, D. M.

2015-12-01

A zonal scheme for the Lower Paleogene of the northern Pacific Ocean is proposed on the basis of the stratigraphic distribution of benthic foraminifers in the lower bathyal-abyssal beds studied in boreholes in the North and South Pacific regions. This scheme includes eight subdivisions (six zones and two subzones). The boundaries of the benthic zonal subdivisions are defined by bioevents (appearance or disappearance of stratigraphically important taxa) and are linked to the zonal scales based on planktonic foraminifers and calcareous nannoplankton. It is established that most of these bioevents are recognized subglobally. Apart from the evolutionary events, changes in the deep-water benthic foraminiferal assemblages were caused by changes in the paleooceanological environment. This allowed detailed characterization of a global mass extinction of assemblages of deep-water benthic foraminifers in the region studied. It is also established that changes in the assemblages of deep-water benthic foraminifers, observed in either change in their taxonomic composition or changes in abundance and diversity, resulted from the presence of different deep-water masses in the region.

On the fast zonal transport of the STS-121 space shuttle exhaust plume in the lower thermosphere

NASA Astrophysics Data System (ADS)

Yue, Jia; Liu, Han-Li; Meier, R. R.; Chang, Loren; Gu, Sheng-Yang; Russell, James, III

2013-03-01

Meier et al. (2011) reported rapid eastward transport of the STS-121 space shuttle (launch: July 4, 2006) main engine plume in the lower thermosphere, observed in hydrogen Lyman α images by the GUVI instrument onboard the TIMED satellite. In order to study the mechanism of the rapid zonal transport, diagnostic tracer calculations are performed using winds from the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM) simulation of July, 2006. It is found that the strong eastward jet at heights of 100-110 km, where the exhaust plume was deposited, results in a persistent eastward tracer motion with an average velocity of 45 m/s. This is generally consistent with, though faster than, the prevailing eastward shuttle plume movement with daily mean velocity of 30 m/s deduced from the STS-121 GUVI observation. The quasi-two-day wave (QTDW) was not included in the numerical simulation because it was found not to be large. Its absence, however, might be partially responsible for insufficient meridional transport to move the tracers away from the fast jet in the simulation. The current study and our model results from Yue and Liu (2010) explain two very different shuttle plume transport scenarios (STS-121 and STS-107 (launch: January 16, 2003), respectively): we conclude that lower thermospheric dynamics is sufficient to account for both very fast zonal motion (zonal jet in the case of STS-121) and very fast meridional motion to polar regions (large QTDW in the case of STS-107).

Role of Atmospheric Transport on the Arctic Amplification: Adjusting Role

NASA Astrophysics Data System (ADS)

KUG, J.; Yim, B.; Jin, F.

2013-12-01

It is controversial whether the atmospheric transport plays a role in arctic amplification. Recently, Hwang et al. (2011) showed that the magnitude of the arctic amplification is negatively correlated with anomalous poleward atmospheric transport. That is, when the arctic amplification is strong (weak), the atmospheric transport plays a negative (positive) role in the arctic amplification. In this study, it is discussed what is a physical mechanism to determine the role of atmospheric transport and relation with the arctic amplification. Here, we suggest adjusting roles of atmospheric transport. The strength of local feedback over the Arctic determines zonal wind changes. The zonal wind changes are determined by two factors. The first one is polar cap cooling, and second is surface warming. They play opposite roles. So, there will be two different zonal wind responses in high-latitude to the greenhouse warming. Depending on the zonal wind response, the atmospheric transport can play a different role because the zonal wind changes can organize synoptic eddy feedbacks including heat flux, which largely contributes to poleward energy transport. We show here that when polar cap cooling is strong, and surface warming over Arctic is relatively weak, the Jet stream tends to be shifted poleward, so it leads to poleward atmospheric transport. On the other hand, when the surface warming is too strong, it lead to southward shift of Jet stream and equatorward atmospheric transport, which paly a negative role in the Arctic amplification.

High-fidelity simulations of unsteady civil aircraft aerodynamics: stakes and perspectives. Application of zonal detached eddy simulation.

PubMed

Deck, Sébastien; Gand, Fabien; Brunet, Vincent; Ben Khelil, Saloua

2014-08-13

This paper provides an up-to-date survey of the use of zonal detached eddy simulations (ZDES) for unsteady civil aircraft applications as a reflection on the stakes and perspectives of the use of hybrid methods in the framework of industrial aerodynamics. The issue of zonal or non-zonal treatment of turbulent flows for engineering applications is discussed. The ZDES method used in this article and based on a fluid problem-dependent zonalization is briefly presented. Some recent landmark achievements for conditions all over the flight envelope are presented, including low-speed (aeroacoustics of high-lift devices and landing gear), cruising (engine-airframe interactions), propulsive jets and off-design (transonic buffet and dive manoeuvres) applications. The implications of such results and remaining challenges in a more global framework are further discussed. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Rossby and drift wave turbulence and zonal flows: The Charney-Hasegawa-Mima model and its extensions

NASA Astrophysics Data System (ADS)

Connaughton, Colm; Nazarenko, Sergey; Quinn, Brenda

2015-12-01

A detailed study of the Charney-Hasegawa-Mima model and its extensions is presented. These simple nonlinear partial differential equations suggested for both Rossby waves in the atmosphere and drift waves in a magnetically-confined plasma, exhibit some remarkable and nontrivial properties, which in their qualitative form, survive in more realistic and complicated models. As such, they form a conceptual basis for understanding the turbulence and zonal flow dynamics in real plasma and geophysical systems. Two idealised scenarios of generation of zonal flows by small-scale turbulence are explored: a modulational instability and turbulent cascades. A detailed study of the generation of zonal flows by the modulational instability reveals that the dynamics of this zonal flow generation mechanism differ widely depending on the initial degree of nonlinearity. The jets in the strongly nonlinear case further roll up into vortex streets and saturate, while for the weaker nonlinearities, the growth of the unstable mode reverses and the system oscillates between a dominant jet, which is slightly inclined to the zonal direction, and a dominant primary wave. A numerical proof is provided for the extra invariant in Rossby and drift wave turbulence-zonostrophy. While the theoretical derivations of this invariant stem from the wave kinetic equation which assumes weak wave amplitudes, it is shown to be relatively well-conserved for higher nonlinearities also. Together with the energy and enstrophy, these three invariants cascade into anisotropic sectors in the k-space as predicted by the Fjørtoft argument. The cascades are characterised by the zonostrophy pushing the energy to the zonal scales. A small scale instability forcing applied to the model has demonstrated the well-known drift wave-zonal flow feedback loop. The drift wave turbulence is generated from this primary instability. The zonal flows are then excited by either one of the generation mechanisms, extracting energy from the drift waves as they grow. Eventually the turbulence is completely suppressed and the zonal flows saturate. The turbulence spectrum is shown to diffuse in a manner which has been mathematically predicted. The insights gained from this simple model could provide a basis for equivalent studies in more sophisticated plasma and geophysical fluid dynamics models in an effort to fully understand the zonal flow generation, the turbulent transport suppression and the zonal flow saturation processes in both the plasma and geophysical contexts as well as other wave and turbulence systems where order evolves from chaos.

Temporal Variability and Latitudinal Jets in Venus's Zonal Wind Profiles

NASA Astrophysics Data System (ADS)

Young, Eliot F.; Bullock, M. A.; Tavenner, T.; Coyote, S.; Murphy, J. R.

2008-09-01

We have observed Venus's night hemisphere from NASA's IRTF (Infrared Telescope Facility) during each inferior conjunction since 2001 to quantify the motion of features in Venus's lower and middle cloud decks. We now present latitudinal profiles from 11 nights, obtained in May and July 2004, February 2006 and September 2007. In about 7 of the 11 nights there are zonal jets near 45N and/or -50S, with speed differentials of 5 to 15 m/s relative to the adjacent equatorward latitude bands. These jets may be evidence of episodic Hadley cell-type circulation. About half of the nights show relatively constant velocity profiles between the latitudes of 50N to 50S, suggesting that considerable mixing is taking place between latitudes. Our most remarkable result is the temporal variability in the median zonal speeds from day to day. For example, the median velocity near the equator increases from 53 to 65 m/s over the period from July 11 - 13, 2004, and increases from 65 to 82 m/s over the period from Sept. 9 - 11, 2007. These velocity changes are too great to be due to the tracking of clouds that are in the middle vs. lower cloud deck, nor can they be caused by clouds that occupy different altitudes; a velocity variation of 25% corresponds to an altitude difference of 15 km, based on vertical profiles of zonal windspeeds from tracking of Pioneer Venus and Venera descent probes. Fifteen km is greater than the expected variation in either cloud base. VIRTIS observations of Venus's southern hemisphere were also obtained in September 2007 and should be able to corroborate or contradict the observed variations. This work was supported by NASA's Planetary Astronomy and Atmospheres programs.

Direct evidence of stationary zonal flows and critical gradient behavior for Er during formation of the edge pedestal in JET

NASA Astrophysics Data System (ADS)

Hillesheim, Jon

2015-11-01

High spatial resolution measurements with Doppler backscattering in JET have provided new insights into the development of the edge radial electric field during pedestal formation. The characteristics of Er have been studied as a function of density at 2.5 MA plasma current and 3 T toroidal magnetic field. We observe fine-scale spatial structure in the edge Er well prior to the LH transition, consistent with stationary zonal flows. Zonal flows are a fundamental mechanism for the saturation of turbulence and this is the first direct evidence of stationary zonal flows in a tokamak. The radial wavelength of the zonal flows systematically decreases with density. The zonal flows are clearest in Ohmic conditions, weaker in L-mode, and absent in H-mode. Measurements also show that after neutral beam heating is applied, the edge Er builds up at a constant gradient into the core during L-mode, at radii where Er is mainly due to toroidal velocity. The local stability of velocity shear driven turbulence, such as the parallel velocity gradient mode, will be assessed with gyrokinetic simulations. This critical Er shear persists across the LH transition into H-mode. Surprisingly, a reduction in the apparent magnitude of the Er well depth is observed directly following the LH transition at high densities. Establishing the physics basis for the LH transition is important for projecting scalings to ITER and these observations challenge existing models based on increased Er shear or strong zonal flows as the trigger for the transition. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

Sensitivity of Coupled Tropical Pacific Model Biases to Convective Parameterization in CESM1

NASA Astrophysics Data System (ADS)

Woelfle, M. D.; Yu, S.; Bretherton, C. S.; Pritchard, M. S.

2018-01-01

Six month coupled hindcasts show the central equatorial Pacific cold tongue bias development in a GCM to be sensitive to the atmospheric convective parameterization employed. Simulations using the standard configuration of the Community Earth System Model version 1 (CESM1) develop a cold bias in equatorial Pacific sea surface temperatures (SSTs) within the first two months of integration due to anomalous ocean advection driven by overly strong easterly surface wind stress along the equator. Disabling the deep convection parameterization enhances the zonal pressure gradient leading to stronger zonal wind stress and a stronger equatorial SST bias, highlighting the role of pressure gradients in determining the strength of the cold bias. Superparameterized hindcasts show reduced SST bias in the cold tongue region due to a reduction in surface easterlies despite simulating an excessively strong low-level jet at 1-1.5 km elevation. This reflects inadequate vertical mixing of zonal momentum from the absence of convective momentum transport in the superparameterized model. Standard CESM1simulations modified to omit shallow convective momentum transport reproduce the superparameterized low-level wind bias and associated equatorial SST pattern. Further superparameterized simulations using a three-dimensional cloud resolving model capable of producing realistic momentum transport simulate a cold tongue similar to the default CESM1. These findings imply convective momentum fluxes may be an underappreciated mechanism for controlling the strength of the equatorial cold tongue. Despite the sensitivity of equatorial SST to these changes in convective parameterization, the east Pacific double-Intertropical Convergence Zone rainfall bias persists in all simulations presented in this study.

Geometrical constraint on the localization of deep water formation

NASA Astrophysics Data System (ADS)

Ferreira, D.; Marshall, J.

2008-12-01

That deep water formation occurs in the North Atlantic and not North Pacific is one of the most notable features of the present climate. In an effort to build a system able to mimic such basic aspects of climate using a minimal description, we study here the influence of ocean geometry on the localization of deep water formation. Using the MIT GCM, two idealized configurations of an ocean-atmosphere-sea ice climate system are studied: Drake and Double-Drake. In Drake, one narrow barrier extends from the North Pole to 35°S while, in Double-Drake, two such barriers set 90° apart join at the North Pole to delimit a Small and a Large basin. Despite the different continental configurations, the two climates are strikingly similar in the zonal average (almost identical heat and fresh water transports, and meridional overturning circulation). However, regional circulations in the Small and Large basins exhibit distinctive Atlantic-like and Pacific-like characteristics: the Small basin is warmer and saltier than the Large one, concentrates dense water formation and deep overturning circulation and achieve the largest fraction of the northward ocean heat transport. We show that the warmer temperature and higher evaporation over the Small basin is not its distinguishing factor. Rather, it is the width of the basin in relation to the zonal fetch of the precipitation pattern. This generates a deficit/excess of precipitation over the Small/Large basin: a fraction of the moisture evaporated from the Small basin is transported zonally and rains out over the Large basin. This creates a salt contrast between the 2 basins, leading to the localization of deep convection in the salty Small basin. Finally, given on the broad similarities between the Double-Drake and real World, we suggest that many gross features that define the present climate are a consequence of 2 asymmetries: a meridional asymmetry (a zonally unblocked southern/blocked northern ocean) and a zonal one (a small and a large basin in the northern hemisphere).

Use of satellite data and modeling to assess the influence of stratospheric processes on the troposphere

NASA Astrophysics Data System (ADS)

Nathan, Terrence

1991-09-01

Over the past forty years, numerous linear stability studies have been performed in order to explain the origin and structure of observed waves in the atmosphere. Of these studies, only a small fraction have considered the stability of time-dependent, zonally varying flow or the influence of radiative-photochemical feedbacks on the stability of zonally uniform flow. The stability of such flows is described, and these flows may yield important information concerning the origin, structure, and transient time scales of free waves in the atmosphere. During the period 1990 to 1991, a beta-plane model that couples radiative transfer, ozone advection, and ozone photochemistry with the quasigeostrophic dynamical circulation was developed in order to study the diabatic effects of Newtonian cooling and ozone-dynamics interaction on the linear stability of free planetary waves in the atmosphere. The stability of a basic state consisting of a westward-moving wave and a zonal mean jet was examined using a linearized, nondivergent barotropic model on sphere. The sensitivity of the stability of the flow to the strength and structure of the zonal jet was emphasized. The current research is focused on the following problems: (1) examination of the finite amplitude interactions among radiation, ozone, and dynamics; and (2) examination of the role of seasonal forcing in short-term climate variability. The plans for next year are presented.

An Assessment of Research Gaps Related to Deep Water Wellbore Integrity

NASA Astrophysics Data System (ADS)

Tkach, M. K.; Radonjic, M.; Kutchko, B. G.

2017-12-01

In order for a deep-water wellbore to uphold its integrity under high pressure - high temperature conditions, the wellbore must possess complete zonal isolation while surrounded in an extreme environment. Highly variable temperature and pressure ranges, shallow flow zones, as well as potentially corrosive fluids and gasses all present unique challenges to the job of the cement which maintains that zonal isolation. As such, alternative options to mainstream choices often present themselves as attractive avenues of discovery. As it is of utmost importance to maintain structural integrity under HPHT conditions, cement slurries are pumped downhole to provide zonal isolation and structural support to offshore wells. The wellbore system potentially faces a variety of temperature and pressure fluctuations from the immediate onset. These fluctuations may affect the hydration properties of the cement. It is also important to consider the chemical interactions that the cement may have at the rock-cement interface where potential degradation or annulus gaps may occur further risking a decrease in zonal isolation. This presentation intends to review some of the important issues regarding zonal isolation in HPHT conditions and to highlight critical knowledge gaps in order to generate important research questions.

The effects of blocking in the subtropics on the phase speed of the MJO

NASA Astrophysics Data System (ADS)

Roundy, P. E.

2016-12-01

The phase speed of the MJO might be regulated by many different factors. Previous works have suggested that moist processes govern the phase speed, and our results show that intensification of convection is associated with reduction of phase speed down to about 5 ms-1. However, convection and rainfall decline with declining phase speeds below 5 ms-1. This presentation shows that increased Rossby wave breaking and blocking east of MJO deep convection is associated with reduced phase speed below about 6 ms-1. A wavelet filter is applied to extract time series characterized by selected zonal wavenumbers and frequencies at select equatorial base longitudes over the Indian and West Pacific Oceans. Results show that anomalies of active convection characterized by wavenumber 2 (the dominant scale of MJO convection over the warm pool) are associated with meridional potential vorticity (PV) gradients across the tropics to the east of the active convection that are near climatology for events moving east at 5 ms-1. These gradients are much weaker for slower events. The slowest phase speed events have almost no meridional PV gradients across the tropics between the mean latitudes of the subtropical jet streams, suggesting that jet exit regions occur immediately east of the deep convection, dumping mass in the upper troposphere over the region of suppressed convection. In the absence of PV gradients, synoptic to planetary scale waves moving into that environment break or cease to propagate linearly.

Prediction of Rare Transitions in Planetary Atmosphere Dynamics Between Attractors with Different Number of Zonal Jets

NASA Astrophysics Data System (ADS)

Bouchet, F.; Laurie, J.; Zaboronski, O.

2012-12-01

We describe transitions between attractors with either one, two or more zonal jets in models of turbulent atmosphere dynamics. Those transitions are extremely rare, and occur over times scales of centuries or millennia. They are extremely hard to observe in direct numerical simulations, because they require on one hand an extremely good resolution in order to simulate accurately the turbulence and on the other hand simulations performed over an extremely long time. Those conditions are usually not met together in any realistic models. However many examples of transitions between turbulent attractors in geophysical flows are known to exist (paths of the Kuroshio, Earth's magnetic field reversal, atmospheric flows, and so on). Their study through numerical computations is inaccessible using conventional means. We present an alternative approach, based on instanton theory and large deviations. Instanton theory provides a way to compute (both numerically and theoretically) extremely rare transitions between turbulent attractors. This tool, developed in field theory, and justified in some cases through the large deviation theory in mathematics, can be applied to models of turbulent atmosphere dynamics. It provides both new theoretical insights and new type of numerical algorithms. Those algorithms can predict transition histories and transition rates using numerical simulations run over only hundreds of typical model dynamical time, which is several order of magnitude lower than the typical transition time. We illustrate the power of those tools in the framework of quasi-geostrophic models. We show regimes where two or more attractors coexist. Those attractors corresponds to turbulent flows dominated by either one or more zonal jets similar to midlatitude atmosphere jets. Among the trajectories connecting two non-equilibrium attractors, we determine the most probable ones. Moreover, we also determine the transition rates, which are several of magnitude larger than a typical time determined from the jet structure. We discuss the medium-term generalization of those results to models with more complexity, like primitive equations or GCMs.

Planetary wave-mean flow interaction in the stratosphere: A comparison between the Northern and Southern Hemispheres

NASA Technical Reports Server (NTRS)

Shiotani, M.; Hirota, I.

1985-01-01

Based on satellite-derived data supplied by the National Meteorological Center (NMC), the dynamical interaction between planetary waves and mean zonal winds in the stratosphere is investigated. Special attention is paid to the differences between the Northern Hemisphere (NH) and the Southern Hemisphere (SH). An analysis is made using Eliassen-Palm (E-P) flux diagnostics for the period from June 1981 to May 1982. In a climatological sense, different seasonal evolutions of large-scale motions between the NH and the SH in the stratosphere are demonstrated. Vertical cross-section analysis is presented to show the day-to-day variation in the mean zonal wind and wave activity, in particular, the following phenomena: (1) the poleward shifting of the westerly jet, and (2) episodes after the shifting of the westerly jet.

Spatially Resolved Sub-millimeter Continuum Imaging of Neptune with ALMA

NASA Astrophysics Data System (ADS)

Iino, Takahiro; Yamada, Takayoshi

2018-02-01

This paper reports the result of spatially resolved 646 GHz sub-millimeter imaging observation of Neptune obtained by the Atacama Large Millimeter and sub-millimeter Array. The observation was performed in 2012 August as the flux calibration and synthesized beam size were small enough to resolve Neptune’s disk at this time. This analysis aims to constrain the vertical structure of deep and upper-tropospheric South polar hot spot detected previously with mid-IR, millimeter, and centimeter wavelength. The probed atmospheric pressure region estimated by the radiative-transfer method was between 1.0 and 0.6 bar for the nadir and South pole views, respectively. The South polar hot spot was not detected clearly with an uncertainty of 2.1 K. The apparent discontinuity of tropospheric and stratospheric hot spot may be caused by the vertical wind shear of South polar zonal jet.

Mapping potential vorticity dynamics on saturn: Zonal mean circulation from Cassini and Voyager data

NASA Astrophysics Data System (ADS)

Read, P. L.; Conrath, B. J.; Fletcher, L. N.; Gierasch, P. J.; Simon-Miller, A. A.; Zuchowski, L. C.

2009-12-01

Maps of Ertel potential vorticity on isentropic surfaces (IPV) and quasi-geostrophic potential vorticity (QGPV) are well established in dynamical meteorology as powerful sources of insight into dynamical processes involving 'balanced' flow (i.e. geostrophic or similar). Here we derive maps of zonal mean IPV and QGPV in Saturn's upper troposphere and lower stratosphere by making use of a combination of velocity measurements, derived from the combined tracking of cloud features in images from the Voyager and Cassini missions, and thermal measurements from the Cassini Composite Infrared Spectrometer (CIRS) instrument. IPV and QGPV are mapped and compared for the entire globe between latitudes 89∘S-82∘N. As on Jupiter, profiles of zonally averaged PV show evidence for a step-like "stair-case" pattern suggestive of local PV homogenisation, separated by strong PV gradients in association with eastward jets. The northward gradient of PV (IPV or QGPV) is found to change sign in several places in each hemisphere, however, even when baroclinic contributions are taken into account. The stability criterion with respect to Arnol'd's second stability theorem may be violated near the peaks of westward jets. Visible, near-IR and thermal-IR Cassini observations have shown that these regions exhibit many prominent, large-scale eddies and waves, e.g. including 'storm alley'. This suggests the possibility that at least some of these features originate from instabilities of the background zonal flow.

Strong Temporal Variation Over One Saturnian Year: From Voyager to Cassini

NASA Technical Reports Server (NTRS)

Li, Liming; Achterberg, Richard K.; Conrath, Barney J.; Gierasch, Peter J.; Smith, Mark A.; Simon-Miller, Amy A.; Nixon, Conor A.; Orton, Glenn S.; Flasar, F. Michael; Jiang, Xun;

Strong Temporal Variation Over One Saturnian Year: From Voyager to Cassini

PubMed Central

Li, Liming; Achterberg, Richard K.; Conrath, Barney J.; Gierasch, Peter J.; Smith, Mark A.; Simon-Miller, Amy A.; Nixon, Conor A.; Orton, Glenn S.; Flasar, F. Michael; Jiang, Xun; Baines, Kevin H.; Morales-Juberías, Raúl; Ingersoll, Andrew P.; Vasavada, Ashwin R.; Del Genio, Anthony D.; West, Robert A.; Ewald, Shawn P.

2013-01-01

Here we report the combined spacecraft observations of Saturn acquired over one Saturnian year (~29.5 Earth years), from the Voyager encounters (1980–81) to the new Cassini reconnaissance (2009–10). The combined observations reveal a strong temporal increase of tropic temperature (~10 Kelvins) around the tropopause of Saturn (i.e., 50 mbar), which is stronger than the seasonal variability (~a few Kelvins). We also provide the first estimate of the zonal winds at 750 mbar, which is close to the zonal winds at 2000 mbar. The quasi-consistency of zonal winds between these two levels provides observational support to a numerical suggestion inferring that the zonal winds at pressures greater than 500 mbar do not vary significantly with depth. Furthermore, the temporal variation of zonal winds decreases its magnitude with depth, implying that the relatively deep zonal winds are stable with time. PMID:23934437

DOE Office of Scientific and Technical Information (OSTI.GOV)

Staten, Paul; Reichler, Thomas; Lu, Jian

Tropospheric circulation shifts have strong potential to impact surface climate. But the magnitude of these shifts in a changing climate, and the attending regional hydrological changes, are difficult to project. Part of this difficulty arises from our lack of understanding of the physical mechanisms behind the circulation shifts themselves. In order to better delineate circulation shifts and their respective causes, we decompose the circulation response into (1) the "direct" response to radiative forcings themselves, and (2) the "indirect" response to changing sea surface temperatures. Using ensembles of 90-day climate model simulations with immediate switch-on forcings, including perturbed greenhouse gas concentrations,more » stratospheric ozone concentrations, and sea surface temperatures, we document the direct and indirect transient responses of the zonal mean general circulation, and investigate the roles of previously proposed mechanisms in shifting the midlatitude jet. We find that both the direct and indirect wind responses often begin in the lower stratosphere. Changes in midlatitude eddies are ubiquitous and synchronous with the midlatitude zonal wind response. Shifts in the critical latitude of wave absorption on either flank of the jet are not indicted as primary factors for the poleward shifting jet, although we see some evidence for increasing equatorward wave reflection over the southern hemisphere in response to sea surface warming. Mechanisms for the northern hemisphere jet shift are less clear.« less

Impact of Stratospheric Ozone Zonal Asymmetries on the Tropospheric Circulation

NASA Technical Reports Server (NTRS)

Tweedy, Olga; Waugh, Darryn; Li, Feng; Oman, Luke

2015-01-01

The depletion and recovery of Antarctic ozone plays a major role in changes of Southern Hemisphere (SH) tropospheric climate. Recent studies indicate that the lack of polar ozone asymmetries in chemistry climate models (CCM) leads to a weaker and warmer Antarctic vortex, and smaller trends in the tropospheric mid-latitude jet and the surface pressure. However, the tropospheric response to ozone asymmetries is not well understood. In this study we report on a series of integrations of the Goddard Earth Observing System Chemistry Climate Model (GEOS CCM) to further examine the effect of zonal asymmetries on the state of the stratosphere and troposphere. Integrations with the full, interactive stratospheric chemistry are compared against identical simulations using the same CCM except that (1) the monthly mean zonal mean stratospheric ozone from first simulation is prescribed and (2) ozone is relaxed to the monthly mean zonal mean ozone on a three day time scale. To analyze the tropospheric response to ozone asymmetries, we examine trends and quantify the differences in temperatures, zonal wind and surface pressure among the integrations.

Vertical structure of tropospheric winds on gas giants

NASA Astrophysics Data System (ADS)

Scott, R. K.; Dunkerton, T. J.

2017-04-01

Zonal mean zonal velocity profiles from cloud-tracking observations on Jupiter and Saturn are used to infer latitudinal variations of potential temperature consistent with a shear stable potential vorticity distribution. Immediately below the cloud tops, density stratification is weaker on the poleward and stronger on the equatorward flanks of midlatitude jets, while at greater depth the opposite relation holds. Thermal wind balance then yields the associated vertical shears of midlatitude jets in an altitude range bounded above by the cloud tops and bounded below by the level where the latitudinal gradient of static stability changes sign. The inferred vertical shear below the cloud tops is consistent with existing thermal profiling of the upper troposphere. The sense of the associated mean meridional circulation in the upper troposphere is discussed, and expected magnitudes are given based on existing estimates of the radiative timescale on each planet.

MJO Signals in Latent Heating: Results from TRMM Retrievals

NASA Technical Reports Server (NTRS)

Zhang, Chidong; Ling, Jian; Hagos, Samson; Tao, Wei-Kuo; Lang, Steve; Takayabu, Yukari N.; Shige, Shoichi; Katsumata, Masaki; Olson, William S.; L'Ecuyer, Tristan

2010-01-01

The Madden-Julian Oscillation (MJO) is the dominant intraseasonal signal in the global tropical atmosphere. Almost all numerical climate models have difficulty to simulate realistic MJO. Four TRMM datasets of latent heating were diagnosed for signals in the MJO. In all four datasets, vertical structures of latent heating are dominated by two components, one deep with its peak above the melting level and one shallow with its peak below. Profiles of the two components are nearly ubiquitous in longitude, allowing a separation of the vertical and zonal/temporal variations when the latitudinal dependence is not considered. All four datasets exhibit robust MJO spectral signals in the deep component as eastward propagating spectral peaks centered at period of 50 days and zonal wavenumber 1, well distinguished from lower- and higher-frequency power and much stronger than the corresponding westward power. The shallow component shows similar but slightly less robust MJO spectral peaks. MJO signals were further extracted from a combination of band-pass (30 - 90 day) filtered deep and shallow components. Largest amplitudes of both deep and shallow components of the MJO are confined to the Indian and western Pacific Oceans. There is a local minimum in the deep components over the Maritime Continent. The shallow components of the MJO differ substantially among the four TRMM datasets in their detailed zonal distributions in the eastern hemisphere. In composites of the heating evolution through the life cycle of the MJO, the shallow components lead the deep ones in some datasets and at certain longitudes. In many respects, the four TRMM datasets agree well in their deep components, but not in their shallow components and the phase relations between the deep and shallow components. These results indicate that caution must be exercised in applications of these latent heating data.

A simple inertial model for Neptune's zonal circulation

NASA Technical Reports Server (NTRS)

Allison, Michael; Lumetta, James T.

1990-01-01

Voyager imaging observations of zonal cloud-tracked winds on Neptune revealed a strongly subrotational equatorial jet with a speed approaching 500 m/s and generally decreasing retrograde motion toward the poles. The wind data are interpreted with a speculative but revealingly simple model based on steady gradient flow balance and an assumed global homogenization of potential vorticity for shallow layer motion. The prescribed model flow profile relates the equatorial velocity to the mid-latitude shear, in reasonable agreement with the available data, and implies a global horizontal deformation scale L(D) of about 3000 km.

Three-dimensional assembly of tissue-engineered cartilage constructs results in cartilaginous tissue formation without retainment of zonal characteristics.

PubMed

Schuurman, W; Harimulyo, E B; Gawlitta, D; Woodfield, T B F; Dhert, W J A; van Weeren, P R; Malda, J

2016-04-01

Articular cartilage has limited regenerative capabilities. Chondrocytes from different layers of cartilage have specific properties, and regenerative approaches using zonal chondrocytes may yield better replication of the architecture of native cartilage than when using a single cell population. To obtain high seeding efficiency while still mimicking zonal architecture, cell pellets of expanded deep zone and superficial zone equine chondrocytes were seeded and cultured in two layers on poly(ethylene glycol)-terephthalate-poly(butylene terephthalate) (PEGT-PBT) scaffolds. Scaffolds seeded with cell pellets consisting of a 1:1 mixture of both cell sources served as controls. Parallel to this, pellets of superficial or deep zone chondrocytes, and combinations of the two cell populations, were cultured without the scaffold. Pellet cultures of zonal chondrocytes in scaffolds resulted in a high seeding efficiency and abundant cartilaginous tissue formation, containing collagen type II and glycosaminoglycans (GAGs) in all groups, irrespective of the donor (n = 3), zonal population or stratified scaffold-seeding approach used. However, whereas total GAG production was similar, the constructs retained significantly more GAG compared to pellet cultures, in which a high percentage of the produced GAGs were secreted into the culture medium. Immunohistochemistry for zonal markers did not show any differences between the conditions. We conclude that spatially defined pellet culture in 3D scaffolds is associated with high seeding efficiency and supports cartilaginous tissue formation, but did not result in the maintenance or restoration of the original zonal phenotype. The use of pellet-assembled constructs leads to a better retainment of newly produced GAGs than the use of pellet cultures alone. Copyright © 2013 John Wiley & Sons, Ltd.

Climatology of the African Easterly Jet and Subtropical Highs over North Africa and Arabian Peninsula and a Numerical Case Study of an Intense African Easterly Wave

NASA Astrophysics Data System (ADS)

Spinks, James D.

North African climate is analyzed between 1979 and 2010 with an emphasis on August using the European Center for Medium Range Weather Forecast (ECMWF) global dataset to investigate the effects of the subtropical anticyclones over North Africa and the Arabian Peninsula on the Africa easterly jet (AEJ). It was found that the AEJ encloses a core with a local wind maximum (LWM) in both West and East Africa, in which the west LWM core has a higher zonal wind speed. The strength of both cores is distinctly different by way of thermal wind balance. The variability of these synoptic weather features is higher in East Africa. The most noticeable variability of intensity occurred with easterly waves. Maintenance of easterly waves from the Arabian Peninsula into East Africa is dependent on strong zonal gradients from the AEJ. These zonal gradients were induced by the strengthening of the subtropical highs and the presence of a westerly jet in Central Africa and south of the Arabian Peninsula. During positive ENSO periods, these systems are generally weaker while in negative periods are stronger. The origins of an intense African easterly wave (AEW) and mesoscale convective system (MCS) in August 2004 (A04) were traced back to the southern Arabian Peninsula, Asir Mountains, and Ethiopian Highlands using gridded satellite (GridSat) data, ERA-I, and the WRF-ARW model. A vorticity budget was developed to investigate the dynamics and mechanisms that contribute to the formation of A04's vorticity perturbation.

The dynamics of a high-speed Jovian jet

NASA Technical Reports Server (NTRS)

Maxworthy, T.

1984-01-01

New measurements of the velocity field in the neighborhood of the high-speed jet located at approximately 24 deg N latitude in the Jovian atmosphere are presented. The maximum zonal velocity is found to be 182 + or - 10 m/s, located at 23.7 + or - 0.2 deg N and representing the largest velocity measured on the planet. The distinctive cloud markings found close to this latitude are discussed and possible dynamical consequences presented.

Net Influence of an Internally Generated Guasi-biennial Oscillation on Modelled Stratospheric Climate and Chemistry

NASA Technical Reports Server (NTRS)

Hurwitz, Margaret M.; Oman, Luke David; Newman, Paul A.; Song, InSun

2013-01-01

A Goddard Earth Observing System Chemistry- Climate Model (GEOSCCM) simulation with strong tropical non-orographic gravity wave drag (GWD) is compared to an otherwise identical simulation with near-zero tropical non-orographic GWD. The GEOSCCM generates a quasibiennial oscillation (QBO) zonal wind signal in response to a tropical peak in GWD that resembles the zonal and climatological mean precipitation field. The modelled QBO has a frequency and amplitude that closely resembles observations. As expected, the modelled QBO improves the simulation of tropical zonal winds and enhances tropical and subtropical stratospheric variability. Also, inclusion of the QBO slows the meridional overturning circulation, resulting in a generally older stratospheric mean age of air. Slowing of the overturning circulation, changes in stratospheric temperature and enhanced subtropical mixing all affect the annual mean distributions of ozone, methane and nitrous oxide. Furthermore, the modelled QBO enhances polar stratospheric variability in winter. Because tropical zonal winds are easterly in the simulation without a QBO, there is a relative increase in tropical zonal winds in the simulation with a QBO. Extratropical differences between the simulations with and without a QBO thus reflect the westerly shift in tropical zonal winds: a relative strengthening of the polar stratospheric jet, polar stratospheric cooling and a weak reduction in Arctic lower stratospheric ozone.

North Atlantic Jet Variability in PMIP3 LGM Simulations

NASA Astrophysics Data System (ADS)

Hezel, P.; Li, C.

2017-12-01

North Atlantic jet variability in glacial climates has been shown inmodelling studies to be strongly influenced by upstream ice sheettopography. We analyze the results of 8 models from the PMIP3simulations, forced with a hybrid Laurentide Ice Sheet topography, andcompare them to the PMIP2 simulations which were forced with theICE-5G topography, to develop a general understanding of the NorthAtlantic jet and jet variability. The strengthening of the jet andreduced spatial variability is a robust feature of the last glacialmaximum (LGM) simulations compared to the pre-industrial state.However, the canonical picture of the LGM North Atlantic jet as beingmore zonal and elongated compared to pre-industrial climate states isnot a robust result across models, and may have arisen in theliterature as a function of multiple studies performed with the samemodel.

A theory of self-organized zonal flow with fine radial structure in tokamak

NASA Astrophysics Data System (ADS)

Zhang, Y. Z.; Liu, Z. Y.; Xie, T.; Mahajan, S. M.; Liu, J.

2017-12-01

The (low frequency) zonal flow-ion temperature gradient (ITG) wave system, constructed on Braginskii's fluid model in tokamak, is shown to be a reaction-diffusion-advection system; it is derived by making use of a multiple spatiotemporal scale technique and two-dimensional (2D) ballooning theory. For real regular group velocities of ITG waves, two distinct temporal processes, sharing a very similar meso-scale radial structure, are identified in the nonlinear self-organized stage. The stationary and quasi-stationary structures reflect a particular feature of the poloidal group velocity. The equation set posed to be an initial value problem is numerically solved for JET low mode parameters; the results are presented in several figures and two movies that show the spatiotemporal evolutions as well as the spectrum analysis—frequency-wave number spectrum, auto power spectrum, and Lissajous diagram. This approach reveals that the zonal flow in tokamak is a local traveling wave. For the quasi-stationary process, the cycle of ITG wave energy is composed of two consecutive phases in distinct spatiotemporal structures: a pair of Cavitons growing and breathing slowly without long range propagation, followed by a sudden decay into many Instantons that carry negative wave energy rapidly into infinity. A spotlight onto the motion of Instantons for a given radial position reproduces a Blob-Hole temporal structure; the occurrence as well as the rapid decay of Caviton into Instantons is triggered by zero-crossing of radial group velocity. A sample of the radial profile of zonal flow contributed from 31 nonlinearly coupled rational surfaces near plasma edge is found to be very similar to that observed in the JET Ohmic phase [J. C. Hillesheim et al., Phys. Rev. Lett. 116, 165002 (2016)]. The theory predicts an interior asymmetric dipole structure associated with the zonal flow that is driven by the gradients of ITG turbulence intensity.

Evidence for wavelike anomalies with short meridional and large zonal scales in the lower stratospheric temperature field

NASA Technical Reports Server (NTRS)

Stanford, J. L.; Short, D. A.

1981-01-01

Global microwave brightness temperature measurements are analyzed to investigate the range of meridional wavelengths 2000-3000 km where spectral studies reveal larger than expected variance. The data, from the TIROS-N Microwave Sounding Unit, are sensitive to lower stratospheric temperatures (30-150 mb). The results reveal striking temperature anomalies with short meridional wavelengths (2000-3000 km) and long zonal wavelengths (zonal wavenumbers 1-4). The anomalies, with amplitudes approximately 1-2 K, extend from the equatorial region to at least as high as 70 deg N and 70 deg S during January 1979. The features exhibit slow eastward movement or else are nearly stationary for several days. In the Northern Hemisphere, comparison with NMC data reveals that the strongest features tend to be associated with major jet streams.

Still from Processed Movie of Zonal Jets

NASA Image and Video Library

2000-11-21

This image is one frame from a movie clip of cloud motions on Jupiter, from the side of the planet opposite to the Great Red Spot. It was taken in the first week of October 2000 by the narrow-angle camera on NASA Cassini spacecraft,

Climate model biases in jet streams, blocking and storm tracks resulting from missing orographic drag

NASA Astrophysics Data System (ADS)

Pithan, Felix; Shepherd, Theodore G.; Zappa, Giuseppe; Sandu, Irina

2016-07-01

State-of-the art climate models generally struggle to represent important features of the large-scale circulation. Common model deficiencies include an equatorward bias in the location of the midlatitude westerlies and an overly zonal orientation of the North Atlantic storm track. Orography is known to strongly affect the atmospheric circulation and is notoriously difficult to represent in coarse-resolution climate models. Yet how the representation of orography affects circulation biases in current climate models is not understood. Here we show that the effects of switching off the parameterization of drag from low-level orographic blocking in one climate model resemble the biases of the Coupled Model Intercomparison Project Phase 5 ensemble: An overly zonal wintertime North Atlantic storm track and less European blocking events, and an equatorward shift in the Southern Hemispheric jet and increase in the Southern Annular Mode time scale. This suggests that typical circulation biases in coarse-resolution climate models may be alleviated by improved parameterizations of low-level drag.

Tropospheric jet response to Antarctic ozone depletion: An update with Chemistry-Climate Model Initiative (CCMI) models

NASA Astrophysics Data System (ADS)

Son, Seok-Woo; Han, Bo-Reum; Garfinkel, Chaim I.; Kim, Seo-Yeon; Park, Rokjin; Abraham, N. Luke; Akiyoshi, Hideharu; Archibald, Alexander T.; Butchart, N.; Chipperfield, Martyn P.; Dameris, Martin; Deushi, Makoto; Dhomse, Sandip S.; Hardiman, Steven C.; Jöckel, Patrick; Kinnison, Douglas; Michou, Martine; Morgenstern, Olaf; O’Connor, Fiona M.; Oman, Luke D.; Plummer, David A.; Pozzer, Andrea; Revell, Laura E.; Rozanov, Eugene; Stenke, Andrea; Stone, Kane; Tilmes, Simone; Yamashita, Yousuke; Zeng, Guang

2018-05-01

The Southern Hemisphere (SH) zonal-mean circulation change in response to Antarctic ozone depletion is re-visited by examining a set of the latest model simulations archived for the Chemistry-Climate Model Initiative (CCMI) project. All models reasonably well reproduce Antarctic ozone depletion in the late 20th century. The related SH-summer circulation changes, such as a poleward intensification of westerly jet and a poleward expansion of the Hadley cell, are also well captured. All experiments exhibit quantitatively the same multi-model mean trend, irrespective of whether the ocean is coupled or prescribed. Results are also quantitatively similar to those derived from the Coupled Model Intercomparison Project phase 5 (CMIP5) high-top model simulations in which the stratospheric ozone is mostly prescribed with monthly- and zonally-averaged values. These results suggest that the ozone-hole-induced SH-summer circulation changes are robust across the models irrespective of the specific chemistry-atmosphere-ocean coupling.

Longitudinal Variation and Waves in Jupiter's South Equatorial Wind Jet

NASA Technical Reports Server (NTRS)

Simon-Miller, A. A.; Rogers, John H.; Gierasch, Peter J.; Choi, David; Allison, Michael; Adamoli, Gianluigi; Mettig, Hans-Joerg

2012-01-01

We have conducted a detailed study of the cloud features in the strong southern equatorial wind jet near 7.5 S planetographic latitude. To understand the apparent variations in average zonal wind jet velocity at this latitude [e.g.. 1,2,3], we have searched for variations iIi both feature latitude and velocity with longitude and time. In particular, we focused on the repetitive chevron-shaped dark spots visible on most dates and the more transient large anticyclonic system known as the South Equatorial Disturbance (SED). These small dark spots are interpreted as cloud holes, and are often used as material tracers of the wind field.

The Galileo probe Doppler wind experiment: Measurement of the deep zonal winds on Jupiter

NASA Astrophysics Data System (ADS)

Atkinson, David H.; Pollack, James B.; Seiff, Alvin

1998-09-01

During its descent into the upper atmosphere of Jupiter, the Galileo probe transmitted data to the orbiter for 57.5 min. Accurate measurements of the probe radio frequency, driven by an ultrastable oscillator, allowed an accurate time history of the probe motions to be reconstructed. Removal from the probe radio frequency profile of known Doppler contributions, including the orbiter trajectory, the probe descent velocity, and the rotation of Jupiter, left a measurable frequency residual due to Jupiter's zonal winds, and microdynamical motion of the probe from spin, swing under the parachute, atmospheric turbulence, and aerodynamic buffeting. From the assumption of the dominance of the zonal horizontal winds, the frequency residuals were inverted and resulted in the first in situ measurements of the vertical profile of Jupiter's deep zonal winds. A number of error sources with the capability of corrupting the frequency measurements or the interpretation of the frequency residuals were considered using reasonable assumptions and calibrations from prelaunch and in-flight testing. It is found that beneath the cloud tops (about 700 mbar) the winds are prograde and rise rapidly to 170 m/s at 4 bars. Beyond 4 bars to the depth at which the link with the probe was lost, nearly 21 bars, the winds remain constant and strong. Corrections for the high temperatures encountered by the probe have recently been completed and provide no evidence of diminishing or strengthening of the zonal wind profile in the deeper regions explored by the Galileo probe.

Relationship between eastern tropical Pacific cooling and recent trends in the Southern Hemisphere zonal-mean circulation

NASA Astrophysics Data System (ADS)

Clem, Kyle R.; Renwick, James A.; McGregor, James

2017-07-01

During 1979-2014, eastern tropical Pacific sea surface temperatures significantly cooled, which has generally been attributed to the transition of the Pacific Decadal Oscillation to its negative phase after 1999. We find the eastern tropical Pacific cooling to be associated with: (1) an intensified Walker Circulation during austral summer (December-February, DJF) and autumn (March-May, MAM); (2) a weakened South Pacific Hadley cell and subtropical jet during MAM; and (3) a strengthening of the circumpolar westerlies between 50 and 60°S during DJF and MAM. Observed cooling in the eastern tropical Pacific is linearly congruent with 60-80 % of the observed Southern Hemisphere positive zonal-mean zonal wind trend between 50 and 60°S during DJF ( 35 % of the interannual variability), and around half of the observed positive zonal-mean zonal wind trend during MAM ( 15 % of the interannual variability). Although previous studies have linked the strengthened DJF and MAM circumpolar westerlies to stratospheric ozone depletion and increasing greenhouse gases, we note that the continuation of the positive SAM trends into the twenty-first century is partially associated with eastern tropical Pacific cooling, especially during MAM when zonal wind anomalies associated with eastern tropical Pacific cooling project strongly onto the observed trends. Outside of DJF and MAM, eastern tropical Pacific cooling is associated with opposing zonal wind anomalies over the Pacific and Indian sectors, which we infer is the reason for the absence of significant positive SAM trends outside of DJF and MAM despite significant eastern tropical Pacific cooling seen during all seasons.

Meso-beta scale numerical simulation studies of terrain-induced jet streak mass/momentum perturbations

NASA Technical Reports Server (NTRS)

Lin, Yuh-Lang; Kaplan, Michael L.

1993-01-01

The first section is on 3-D numerical modeling of terrain-induced circulations and covers the following: (1) additional insights into gravity wave generation mechanisms based on the control simulation; (2) ongoing nested-grid numerical simulations; (3) work to be completed during the remainder of FY-93; and (4) work objectives for FY-94. The second section is on linear theory and theoretical modeling and covers the following: (1) the free response of a uniform barotropic flow to an initially stationary unbalanced (ageostrophic) zonal wind anomaly; and (2) the free response of a uniform barotropic flow to an initially stationary balanced zonal wind anomaly.

Saturn’s gravitational field induced by its equatorially antisymmetric zonal winds

NASA Astrophysics Data System (ADS)

Kong, Dali; Zhang, Keke; Schubert, Gerald; Anderson, John D.

2018-05-01

The cloud-level zonal winds of Saturn are marked by a substantial equatorially antisymmetric component with a speed of about 50ms‑1 which, if they are sufficiently deep, can produce measurable odd zonal gravitational coefficients ΔJ 2k+1, k = 1, 2, 3, 4. This study, based on solutions of the thermal-gravitational wind equation, provides a theoretical basis for interpreting the odd gravitational coefficients of Saturn in terms of its equatorially antisymmetric zonal flow. We adopt a Saturnian model comprising an ice-rock core, a metallic dynamo region and an outer molecular envelope. We use an equatorially antisymmetric zonal flow that is parameterized, confined in the molecular envelope and satisfies the solvability condition required for the thermal-gravitational wind equation. The structure and amplitude of the zonal flow at the cloud level are chosen to be consistent with observations of Saturn. We calculate the odd zonal gravitational coefficients ΔJ 2k+1, k = 1, 2, 3, 4 by regarding the depth of the equatorially antisymmetric winds as a parameter. It is found that ΔJ 3 is ‑4.197 × 10‑8 if the zonal winds extend about 13 000 km downward from the cloud tops while it is ‑0.765 × 10‑8 if the depth is about 4000 km. The depth/profile of the equatorially antisymmetric zonal winds can eventually be estimated when the high-precision measurements of the Cassini Grand Finale become available.

Zonal flows and turbulence in fluids and plasmas

NASA Astrophysics Data System (ADS)

Parker, Jeffrey Bok-Cheung

In geophysical and plasma contexts, zonal flows are well known to arise out of turbulence. We elucidate the transition from statistically homogeneous turbulence without zonal flows to statistically inhomogeneous turbulence with steady zonal flows. Starting from the Hasegawa--Mima equation, we employ both the quasilinear approximation and a statistical average, which retains a great deal of the qualitative behavior of the full system. Within the resulting framework known as CE2, we extend recent understanding of the symmetry-breaking 'zonostrophic instability'. Zonostrophic instability can be understood in a very general way as the instability of some turbulent background spectrum to a zonally symmetric coherent mode. As a special case, the background spectrum can consist of only a single mode. We find that in this case the dispersion relation of zonostrophic instability from the CE2 formalism reduces exactly to that of the 4-mode truncation of generalized modulational instability. We then show that zonal flows constitute pattern formation amid a turbulent bath. Zonostrophic instability is an example of a Type I s instability of pattern-forming systems. The broken symmetry is statistical homogeneity. Near the bifurcation point, the slow dynamics of CE2 are governed by a well-known amplitude equation, the real Ginzburg-Landau equation. The important features of this amplitude equation, and therefore of the CE2 system, are multiple. First, the zonal flow wavelength is not unique. In an idealized, infinite system, there is a continuous band of zonal flow wavelengths that allow a nonlinear equilibrium. Second, of these wavelengths, only those within a smaller subband are stable. Unstable wavelengths must evolve to reach a stable wavelength; this process manifests as merging jets. These behaviors are shown numerically to hold in the CE2 system, and we calculate a stability diagram. The stability diagram is in agreement with direct numerical simulations of the quasilinear system. The use of statistically-averaged equations and the pattern formation methodology provide a path forward for further systematic investigations of zonal flows and their interactions with turbulence.

A measurement of multi-jet rates in deep-inelastic scattering at HERA

NASA Astrophysics Data System (ADS)

Abt, I.; Ahmed, T.; Andreev, V.; Andrieu, B.; Appuhn, R.-D.; Arpagaus, M.; Babaev, A.; Bärwolff, H.; Bán, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bergstein, H.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besançon, M.; Biddulph, P.; Binder, E.; Bischoff, A.; Bizot, J. C.; Blobel, V.; Borras, K.; Bosetti, P. C.; Boudry, V.; Bourdarios, C.; Brasse, F.; Braun, U.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Clarke, D.; Clegg, A. B.; Colombo, M.; Coughlan, J. A.; Courau, A.; Coutures, Ch.; Cozzika, G.; Criegee, L.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Danilov, M.; Dann, A. W. E.; Dau, W. D.; David, M.; Deffur, E.; Delcourt, B.; Del Buono, L.; Devel, M.; de Roeck, A.; Dingus, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Drescher, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Ebbinghaus, R.; Eberle, M.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellis, N. N.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Fensome, I. F.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Flauger, W.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Fuhrmann, P.; Gabathuler, E.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gellrich, A.; Gennis, M.; Genzel, H.; Gerhards, R.; Godfrey, L.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goodall, A. M.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Greif, H.; Grindhammer, G.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Handschuh, D.; Hanlon, E. M.; Hapke, M.; Harjes, J.; Haydar, R.; Haynes, W. J.; Heatherington, J.; Hedberg, V.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herma, R.; Herynek, I.; Hildesheim, W.; Hill, P.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Huet, Ph.; Hufnagel, H.; Huot, N.; Ibbotson, M.; Itterbeck, H.; Jabiol, M.-A.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Jansen, T.; Jönsson, L.; Johannsen, K.; Johnson, D. P.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kasarian, S.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Kaufmann, H. H.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Ko, W.; Köhler, T.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, U.; Kubenka, J. P.; Küster, H.; Kuhlen, M.; Kurča, T.; Kurzhöfer, J.; Kuznik, B.; Lacour, D.; Lamarche, F.; Lander, R.; Landon, M. P. J.; Lange, W.; Langkau, R.; Lanius, P.; Laporte, J. F.; Lebedev, A.; Leuschner, A.; Leverenz, C.; Levonian, S.; Lewin, D.; Ley, Ch.; Lindner, A.; Lindström, G.; Linsel, F.; Lipinski, J.; Loch, P.; Lohmander, H.; Lopez, G. C.; Lüers, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, A.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Mercer, D.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Mikocki, S.; Milone, V.; Monnier, E.; Moreau, F.; Moreels, J.; Morris, J. V.; Müller, K.; Murín, P.; Murray, S. A.; Nagovizin, V.; Naroska, B.; Naumann, Th.; Newman, P. R.; Newton, D.; Neyret, D.; Nguyen, H. K.; Niebergall, F.; Niebuhr, C.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Orenstein, S.; Ould-Saada, F.; Pascaud, C.; Patel, G. D.; Peppel, E.; Peters, S.; Phillips, H. T.; Phillips, J. P.; Pichler, Ch.; Pilgram, W.; Pitzl, D.; Prell, S.; Prosi, R.; Rädel, G.; Raupach, F.; Rauschnabel, K.; Reimer, P.; Reinshagen, S.; Ribarics, P.; Riech, V.; Riedlberger, J.; Riess, S.; Rietz, M.; Robertson, S. M.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Royon, C.; Rudowicz, M.; Ruffer, M.; Rusakov, S.; Rybicki, K.; Sahlmann, N.; Sanchez, E.; Sankey, D. P. C.; Savitsky, M.; Schacht, P.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmitz, W.; Schöning, A.; Schröder, V.; Schulz, M.; Schwab, B.; Schwind, A.; Scobel, W.; Seehausen, U.; Sell, R.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shooshtari, H.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Smolik, L.; Soloviev, Y.; Spitzer, H.; Staroba, P.; Steenbock, M.; Steffen, P.; Steinberg, R.; Stella, B.; Stephens, K.; Stier, J.; Stösslein, U.; Strachota, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Taylor, R. E.; Tchernyshov, V.; Thiebaux, C.; Thompson, G.; Tichomirov, I.; Truöl, P.; Turnau, J.; Tutas, J.; Urban, L.; Usik, A.; Valkar, S.; Valkarova, A.; Vallée, C.; van Esch, P.; Vartapetian, A.; Vazdik, Y.; Vecko, M.; Verrecchia, P.; Vick, R.; Villet, G.; Vogel, E.; Wacker, K.; Walker, I. W.; Walther, A.; Weber, G.; Wegener, D.; Wegner, A.; Wellisch, H. P.; West, L. R.; Willard, S.; Winde, M.; Winter, G.-G.; Wolff, Th.; Womersley, L. A.; Wright, A. E.; Wulff, N.; Yiou, T. P.; Žáček, J.; Závada, P.; Zeitnitz, C.; Ziaeepour, H.; Zimmer, M.; Zimmermann, W.; Zomer, F.

1994-03-01

Multi-jet production is observed in deep-inelastic electron proton scattering with the H1 detector at HERA. Jet rates for momentum transfers squared up to 500 GeV2 are determined using the JADE jet clustering algorithm. They are found to be in agreement with predictions from QCD based models.

Numerical simulation on zonal disintegration in deep surrounding rock mass.

PubMed

Chen, Xuguang; Wang, Yuan; Mei, Yu; Zhang, Xin

2014-01-01

Zonal disintegration have been discovered in many underground tunnels with the increasing of embedded depth. The formation mechanism of such phenomenon is difficult to explain under the framework of traditional rock mechanics, and the fractured shape and forming conditions are unclear. The numerical simulation was carried out to research the generating condition and forming process of zonal disintegration. Via comparing the results with the geomechanical model test, the zonal disintegration phenomenon was confirmed and its mechanism is revealed. It is found to be the result of circular fracture which develops within surrounding rock mass under the high geostress. The fractured shape of zonal disintegration was determined, and the radii of the fractured zones were found to fulfill the relationship of geometric progression. The numerical results were in accordance with the model test findings. The mechanism of the zonal disintegration was revealed by theoretical analysis based on fracture mechanics. The fractured zones are reportedly circular and concentric to the cavern. Each fracture zone ruptured at the elastic-plastic boundary of the surrounding rocks and then coalesced into the circular form. The geometric progression ratio was found to be related to the mechanical parameters and the ground stress of the surrounding rocks.

Numerical Simulation on Zonal Disintegration in Deep Surrounding Rock Mass

PubMed Central

Chen, Xuguang; Wang, Yuan; Mei, Yu; Zhang, Xin

2014-01-01

Zonal disintegration have been discovered in many underground tunnels with the increasing of embedded depth. The formation mechanism of such phenomenon is difficult to explain under the framework of traditional rock mechanics, and the fractured shape and forming conditions are unclear. The numerical simulation was carried out to research the generating condition and forming process of zonal disintegration. Via comparing the results with the geomechanical model test, the zonal disintegration phenomenon was confirmed and its mechanism is revealed. It is found to be the result of circular fracture which develops within surrounding rock mass under the high geostress. The fractured shape of zonal disintegration was determined, and the radii of the fractured zones were found to fulfill the relationship of geometric progression. The numerical results were in accordance with the model test findings. The mechanism of the zonal disintegration was revealed by theoretical analysis based on fracture mechanics. The fractured zones are reportedly circular and concentric to the cavern. Each fracture zone ruptured at the elastic-plastic boundary of the surrounding rocks and then coalesced into the circular form. The geometric progression ratio was found to be related to the mechanical parameters and the ground stress of the surrounding rocks. PMID:24592166

Impacts of the cloud structure's latitudinal variation on the general circulation of the Venus atmosphere as modeled by the LMD-GCM

NASA Astrophysics Data System (ADS)

Garate-Lopez, Itziar; Lebonnois, Sébastien

2017-04-01

A new simulation of Venus atmospheric circulation obtained with the LMD Venus GCM is described and the impact of cloud's latitudinal structure on the general circulation is analyzed. The model used here is based on that presented in Lebonnois et al. (2016). However, in the present simulation we consider the latitudinal variation of the cloud structure (Haus et al., 2014) both for the solar heating and to compute the infrared net-exchange rate matrix used in the radiative transfer module. The new cloud treatment affects mainly the balance in the angular momentum and the zonal wind distribution. Consequently, the agreement between the vertical profile of the modeled mean zonal wind and the profiles measured by different probes, is clearly improved from previous simulations in which zonal winds below the clouds were weak (roughly half the observed values). Moreover, the equatorial jet obtained at the base of the cloud deck is now more consistent with the observations. In Lebonnois et al. (2016) it was too strong compared to mid-latitudes, but in the present simulation the equatorial jet is less intense than the mid-latitude jets, in concordance with cloud-tracking measurements (Hueso et al., 2015). Since the atmospheric waves play a crucial role in the angular momentum budget of the Venus's atmospheric circulation, we analyze the wave activity by means of the Fast Fourier Transform technique studying the frequency spectrum of temperature, zonal and meridional wind fields. Modifications in the activity of the different types of waves present in the Venusian atmosphere compared to Lebonnois et al. (2016) are discussed, in terms of horizontal and vertical transport of the angular momentum by diurnal and semi-diurnal tides, barotropic and baroclinic waves, and Rossby and Kelvin type waves. Haus R., Kappel D. and Arnold G., 2014. Atmospheric thermal structure and cloud features in the southern hemisphere of Venus as retrieved from VIRTIS/VEX radiation measurements. Icarus 232, 232-248. Hueso R., Peralta J., Garate-Lopez I., et al., 2015. Six years of Venus winds at the upper cloud level from UV, visible and near infrared observations from VIRTIS on Venus express. Planet. Space Sci. 113-114, 78-99. Lebonnois S., Sugimoto N., and Gilli G., 2016. Wave analysis in the atmosphere of Venus below 100km altitude, simulated by the LMD Venus GCM. Icarus 278, 38-51.

Jet production in high Q 2 deep-inelastic ep scattering at HERA

NASA Astrophysics Data System (ADS)

Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Repond, J.; Stanek, R.; Talaga, R. L.; Zhang, H.; Avad, R.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Romeo, G. Cara; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, E.; Polini, A.; Sartorelli, G.; Timellini, R.; Garcia, Y. Zamora; Zichichi, A.; Bargende, A.; Crittenden, J.; Desch, K.; Diekmann, B.; Doeker, T.; Eckert, M.; Feld, L.; Frey, A.; Geerts, M.; Geitz, G.; Grothe, M.; Haas, T.; Hartmann, H.; Haun, D.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mari, S. M.; Mass, A.; Mengel, S.; Mollen, J.; Paul, E.; Rembser, Ch.; Schattevoy, R.; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Dyce, N.; Foster, B.; George, S.; Gilmore, R.; Heath, G. P.; Heath, H. F.; Llewellyn, T. J.; Morgado, C. J. S.; Norman, D. J. P.; O'Mara, J. A.; Tapper, R. I.; Wilson, S. S.; Yoshida, R.; Rau, R. R.; Arneodo, M.; Iannotti, L.; Schioppa, M.; Susinno, G.; Bernstein, A.; Caldwell, A.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Eskreys, K.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Rulikowska-Zarębska, E.; Suszycki, L.; Zając, J.; Kotański, A.; Przybycień, M.; Bauerdick, I. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Coldewey, C.; Deppe, O.; Desler, K.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Gutjahr, B.; Hain, W.; Hasell, D.; Heßling, H.; Hultschig, H.; Iga, Y.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Köpke, L.; Kötz, U.; Kowalski, H.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mańczak, O.; Ng, J. S. T.; Nickel, S.; Notz, D.; Ohrenberg, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Stiliaris, E.; Surrow, B.; Voß, T.; Westphal, D.; Wolf, G.; Youngman, C.; Zhou, J. F.; Grabosch, H. J.; Kharchilava, A.; Leich, A.; Mattingly, M.; Meyer, A.; Schlenstedt, S.; Wulff, N.; Barbagli, G.; Pelfer, P.; Anzivino, G.; Maccarrone, G.; de Pasquale, S.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Freidhof, A.; Söldner-Rembold, S.; Schroeder, J.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Fleck, I.; Saxon, D. H.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Neumann, T.; Sinkus, R.; Wick, K.; Badura, E.; Burow, B. D.; Hagge, L.; Lohrmann, E.; Mainusch, J.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Gallo, E.; Harris, V. L.; Hung, B. Y. H.; Long, K. R.; Miller, D. B.; Morawitz, P. P. O.; Prinias, A.; Sedgbeer, J. K.; Whitfield, A. F.; Mallik, U.; McCliment, E.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Zhang, Y.; Cloth, P.; Filges, D.; An, S. H.; Hong, S. M.; Nam, S. W.; Park, S. K.; Suh, M. H.; Yon, S. H.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Cases, G.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Del Peso, J.; Puga, J.; Terron, J.; de Trocóniz, J. F.; Smith, G. R.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; Laurent, M. St.; Ullmann, R.; Zacek, G.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Y. A.; Kobrin, V. D.; Kuzmin, V. A.; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Botje, M.; Chlebana, F.; Dake, A.; Engelen, J.; de Kamps, M.; Kooijman, P.; Kruse, A.; Tiecke, H.; Verkerke, W.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Honscheid, K.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Park, I. H.; Romanowski, T. A.; Seidlein, R.; Bailey, D. S.; Blair, G. A.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Daniels, D.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Luffman, P. E.; Lindemann, L.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Uijterwaal, H.; Walczak, R.; Wilson, F. F.; Yip, T.; Abbiendi, G.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; de Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Butterworth, J. M.; Feild, R. G.; Oh, B. Y.; Whitmore, J. J.; D'Agostini, G.; Marini, G.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Prytz, K.; Shah, T. P.; Short, T. L.; Barberis, L.; Cartiglia, N.; Dubbs, T.; Heusch, C.; van Hook, M.; Hubbard, B.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Biltzinger, J.; Seifert, R. J.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Levy, A.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kuze, M.; Mine, S.; Nagasawa, Y.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Nakamitsu, Y.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Brkic, M.; Crombie, M. B.; Gingrich, D. M.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Sampson, C. R.; Teuscher, R. J.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Blankenship, K.; Kochocki, J.; Lu, B.; Mo, L. W.; Bogusz, W.; Charchula, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Eisenberg, Y.; Karshon, U.; Revel, D.; Zer-Zion, D.; Ali, I.; Badgett, W. F.; Behrens, B.; Dasu, S.; Fordham, C.; Foudas, C.; Goussiou, A.; Loveless, R. J.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Tsurugai, T.; Bhadra, S.; Cardy, M. L.; Fagerstroem, C.-P.; Frisken, W. R.; Furutani, K. M.; Khakzad, M.; Schmidke, W. B.

1995-03-01

Two-jet production in deep-inelastic electron-proton scattering has been studied for 160< Q 2<1280 GeV2, 0.01< x<0.1 and 0.04< y<0.95 with the ZEUS detector at HERA. The kinematic properties of the jets and the jet production rates are presented. The partonic scaling variables of the two-jet system and the rate of two-jet production are compared to perturbative next-to-leading order QCD calculations.

Unusual behavior of quiet-time zonal and vertical plasma drift velocities over Jicamarca during the recent extended solar minimum of 2008

NASA Astrophysics Data System (ADS)

Santos, Ângela M.; Abdu, Mangalathayil A.; Souza, Jonas R.; Batista, Inez S.; Sobral, José H. A.

2017-11-01

The influence of the recent deep and prolonged solar minimum on the daytime zonal and vertical plasma drift velocities during quiet time is investigated in this work. Analyzing the data obtained from incoherent scatter radar from Jicamarca (11.95° S, 76.87° W) we observe an anomalous behavior of the zonal plasma drift during June 2008 characterized by lower than usual daytime westward drift and its early afternoon reversal to eastward. As a case study the zonal drift observed on 24 June 2008 is modeled using a realistic low-latitude ionosphere simulated by the Sheffield University Plasmasphere-Ionosphere Model-INPE (SUPIM-INPE). The results show that an anomalously low zonal wind was mainly responsible for the observed anomalous behavior in the zonal drift. A comparative study of the vertical plasma drifts obtained from magnetometer data for some periods of maximum (2000-2002) and minimum solar activity (1998, 2008, 2010) phases reveal a considerable decrease on the E-region conductivity and the dynamo electric field during 2008. However, we believe that the contribution of these characteristics to the unusual behavior of the zonal plasma drift is significantly smaller than that arising from the anomalously low zonal wind. The SUPIM-INPE result of the critical frequency of the F layer (foF2) over Jicamarca suggested a lower radiation flux than that predicted by solar irradiance model (SOLAR2000) for June 2008.

Dependence of Arctic climate on the latitudinal position of stationary waves and to high-latitudes surface warming

NASA Astrophysics Data System (ADS)

Shin, Yechul; Kang, Sarah M.; Watanabe, Masahiro

2017-12-01

Previous studies suggest large uncertainties in the stationary wave response under global warming. Here, we investigate how the Arctic climate responds to changes in the latitudinal position of stationary waves, and to high-latitudes surface warming that mimics the effect of Arctic sea ice loss under global warming. To generate stationary waves in an atmospheric model coupled to slab ocean, a series of experiments is performed where the thermal forcing with a zonal wavenumber-2 (with zero zonal-mean) is prescribed at the surface at different latitude bands in the Northern Hemisphere. When the stationary waves are generated in the subtropics, the cooling response dominates over the warming response in the lower troposphere due to cloud radiative effects. Then, the low-level baroclinicity is reduced in the subtropics, which gives rise to a poleward shift of the eddy driven jet, thereby inducing substantial cooling in the northern high latitudes. As the stationary waves are progressively generated at higher latitudes, the zonal-mean climate state gradually becomes more similar to the integration with no stationary waves. These differences in the mean climate affect the Arctic climate response to high-latitudes surface warming. Additional surface heating over the Arctic is imposed to the reference climates in which the stationary waves are located at different latitude bands. When the stationary waves are positioned at lower latitudes, the eddy driven jet is located at higher latitude, closer to the prescribed Arctic heating. As baroclinicity is more effectively perturbed, the jet shifts more equatorward that accompanies a larger reduction in the poleward eddy transport of heat and momentum. A stronger eddy-induced descending motion creates greater warming over the Arctic. Our study calls for a more accurate simulation of the present-day stationary wave pattern to enhance the predictability of the Arctic warming response in a changing climate.

Anomalous behaviors of Wyrtki Jets in the equatorial Indian Ocean during 2013

PubMed Central

Duan, Yongliang; Liu, Lin; Han, Guoqing; Liu, Hongwei; Yu, Weidong; Yang, Guang; Wang, Huiwu; Wang, Haiyuan; Liu, Yanliang; Zahid; Waheed, Hussain

2016-01-01

In-situ measurement of the upper ocean velocity discloses significant abnormal behaviors of two Wyrtki Jets (WJs) respectively in boreal spring and fall, over the tropical Indian Ocean in 2013. The two WJs both occurred within upper 130 m depth and persisted more than one month. The exceptional spring jet in May was unusually stronger than its counterpart in fall, which is clearly against the previous understanding. Furthermore, the fall WJ in 2013 unexpectedly peaked in December, one month later than its climatology. Data analysis and numerical experiments illustrate that the anomalous changes in the equatorial zonal wind, associated with the strong intra-seasonal oscillation events, are most likely the primary reason for such anomalous WJs activities. PMID:27436723

Modeling the zonal disintegration of rocks near deep level tunnels by gradient internal variable continuous phase transition theory

NASA Astrophysics Data System (ADS)

Haoxiang, Chen; Qi, Chengzhi; Peng, Liu; Kairui, Li; Aifantis, Elias C.

2015-12-01

The occurrence of alternating damage zones surrounding underground openings (commonly known as zonal disintegration) is treated as a "far from thermodynamic equilibrium" dynamical process or a nonlinear continuous phase transition phenomenon. The approach of internal variable gradient theory with diffusive transport, which may be viewed as a subclass of Landau's phase transition theory, is adopted. The order parameter is identified with an irreversible strain quantity, the gradient of which enters into the expression for the free energy of the rock system. The gradient term stabilizes the material behavior in the post-softening regime, where zonal disintegration occurs. The results of a simplified linearized analysis are confirmed by the numerical solution of the nonlinear problem.

Large-Scale Flows and Magnetic Fields Produced by Rotating Convection in a Quasi-Geostrophic Model of Planetary Cores

NASA Astrophysics Data System (ADS)

Guervilly, C.; Cardin, P.

2017-12-01

Convection is the main heat transport process in the liquid cores of planets. The convective flows are thought to be turbulent and constrained by rotation (corresponding to high Reynolds numbers Re and low Rossby numbers Ro). Under these conditions, and in the absence of magnetic fields, the convective flows can produce coherent Reynolds stresses that drive persistent large-scale zonal flows. The formation of large-scale flows has crucial implications for the thermal evolution of planets and the generation of large-scale magnetic fields. In this work, we explore this problem with numerical simulations using a quasi-geostrophic approximation to model convective and zonal flows at Re 104 and Ro 10-4 for Prandtl numbers relevant for liquid metals (Pr 0.1). The formation of intense multiple zonal jets strongly affects the convective heat transport, leading to the formation of a mean temperature staircase. We also study the generation of magnetic fields by the quasi-geostrophic flows at low magnetic Prandtl numbers.

A planetary-scale disturbance in the most intense Jovian atmospheric jet from JunoCam and ground-based observations

NASA Astrophysics Data System (ADS)

Sánchez-Lavega, A.; Rogers, J. H.; Orton, G. S.; García-Melendo, E.; Legarreta, J.; Colas, F.; Dauvergne, J. L.; Hueso, R.; Rojas, J. F.; Pérez-Hoyos, S.; Mendikoa, I.; Iñurrigarro, P.; Gomez-Forrellad, J. M.; Momary, T.; Hansen, C. J.; Eichstaedt, G.; Miles, P.; Wesley, A.

2017-05-01

We describe a huge planetary-scale disturbance in the highest-speed Jovian jet at latitude 23.5°N that was first observed in October 2016 during the Juno perijove-2 approach. An extraordinary outburst of four plumes was involved in the disturbance development. They were located in the range of planetographic latitudes from 22.2° to 23.0°N and moved faster than the jet peak with eastward velocities in the range 155 to 175 m s-1. In the wake of the plumes, a turbulent pattern of bright and dark spots (wave number 20-25) formed and progressed during October and November on both sides of the jet, moving with speeds in the range 100-125 m s-1 and leading to a new reddish and homogeneous belt when activity ceased in late November. Nonlinear numerical models reproduce the disturbance cloud patterns as a result of the interaction between local sources (the plumes) and the zonal eastward jet.

Zonal Flows and Turbulence in Fluids and Plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parker, Jeffrey

2014-09-01

In geophysical and plasma contexts, zonal flows are well known to arise out of turbulence. We elucidate the transition from statistically homogeneous turbulence without zonal flows to statistically inhomogeneous turbulence with steady zonal flows. Starting from the Hasegawa--Mima equation, we employ both the quasilinear approximation and a statistical average, which retains a great deal of the qualitative behavior of the full system. Within the resulting framework known as CE2, we extend recent understanding of the symmetry-breaking `zonostrophic instability'. Zonostrophic instability can be understood in a very general way as the instability of some turbulent background spectrum to a zonally symmetricmore » coherent mode. As a special case, the background spectrum can consist of only a single mode. We find that in this case the dispersion relation of zonostrophic instability from the CE2 formalism reduces exactly to that of the 4-mode truncation of generalized modulational instability. We then show that zonal flows constitute pattern formation amid a turbulent bath. Zonostrophic instability is an example of a Type Is instability of pattern-forming systems. The broken symmetry is statistical homogeneity. Near the bifurcation point, the slow dynamics of CE2 are governed by a well-known amplitude equation, the real Ginzburg-Landau equation. The important features of this amplitude equation, and therefore of the CE2 system, are multiple. First, the zonal flow wavelength is not unique. In an idealized, infinite system, there is a continuous band of zonal flow wavelengths that allow a nonlinear equilibrium. Second, of these wavelengths, only those within a smaller subband are stable. Unstable wavelengths must evolve to reach a stable wavelength; this process manifests as merging jets. These behaviors are shown numerically to hold in the CE2 system, and we calculate a stability diagram. The stability diagram is in agreement with direct numerical simulations of the quasilinear system. The use of statistically-averaged equations and the pattern formation methodology provide a path forward for further systematic investigations of zonal flows and their interactions with turbulence.« less

Zonal pressure gradient, velocity and transport in the Atlantic Equatorial Undercurrent from focal cruises (July 1982-February 1984)

NASA Astrophysics Data System (ADS)

Hisard, Philippe; Hénin, Christian

The zonal pressure gradient (ZPG) along the Atlantic equator and the Equatorial Undercurrent (EUC) transport are discussed for four cruises representative of each season. A very clear sea surface slope reversal occurred in the eastern area during autumn as far west as 14°W. An early onset of the equatorial thermocline rising was evident during spring 1983. An eastward equatorial surface jet clearly distinct from the EUC was observed at 35°W and 29°W. The greatest ZPG but the lowest EUC transport were observed during summer 1983. A nearly total absence of the ZPG and a large surfacing of the EUC as far as 10°W characterized the 1984 winter.

Monthly Maps of Sea Surface Height in the North Atlantic and Zonal Indices for the Gulf Stream Using TOPEX/Poseidon Altimeter Data

NASA Technical Reports Server (NTRS)

Singh, Sandipa; Kelly, Kathryn A.

1997-01-01

Monthly Maps of sea surface height are constructed for the North Atlantic Ocean using TOPEX/Poseidon altimeter data. Mean sea surface height is reconstructed using a weighted combination of historical, hydrographic data and a synthetic mean obtained by fitting a Gaussian model of the Gulf Stream jet to altimeter data. The resultant mean shows increased resolution over the hydrographic mean, and incorporates recirculation information that is absent in the synthetic mean. Monthly maps, obtained by adding the mean field to altimeter sea surface height residuals, are used to derive a set of zonal indices that describe the annual cycle of meandering as well as position and strength of the Gulf Stream.

Intraseasonal and Interannual Variability of the Quasi-Two Day Wave in the Northern Hemisphere Summer Mesosphere

NASA Technical Reports Server (NTRS)

McCormack, J. P.; Coy, L.; Singer, W.

2013-01-01

This study uses global synoptic meteorological fields from a high-altitude data assimilation system to investigate the spatial and temporal characteristics of the quasi-2 day wave (Q2DW) and migrating diurnal tide during the Northern Hemisphere summers of 2007, 2008, and 2009. By applying a 2-dimensional fast Fourier transform to meridional wind and temperature fields, we are able to identify Q2DW source regions and to diagnose propagation of Q2DW activity into the upper mesosphere and lower thermosphere. We find that Q2DW is comprised primarily of westward propagating zonal wavenumber 3 and wavenumber 4 components that originate from within baroclinically unstable regions along the equatorward flank of the summer midlatitude easterly jet. Amplitude variations of wavenumbers 3 and 4 tend to be anti-correlated throughout the summer, with wavenumber 3 maximizing in July and wavenumber 4 maximizing in late June and early August. Monthly mean Q2DW amplitudes between 30 50N latitude are largest when diurnal tidal amplitudes are smallest and vice versa. However, there is no evidence of any rapid amplification of the Q2DW via nonlinear interaction with the diurnal tide. Instead, variations of Q2DW amplitudes during July are closely linked to variations in the strength and location of the easterly jet core from one summer to the next, with a stronger jet producing larger Q2DW amplitudes. Linear instability model calculations based on the assimilated wind fields find fast growing zonal wavenumber 3 and 4 modes with periods near 2 days in the vicinity of the easterly jet.

Jetting from impact of a spherical drop with a deep layer

NASA Astrophysics Data System (ADS)

Zhang, Li; Toole, Jameson; Fazzaa, Kamel; Deegan, Robert; Deegan Group Team; X-Ray Science Division, Advanced Photon Source Collaboration

2011-11-01

We performed an experimental study of jets during the impact of a spherical drop with a deep layer of same liquid. Using high speed optical and X-ray imaging, we observe two types of jets: the so-called ejecta sheet which emerges almost immediately after impact and the lamella which emerges later. For high Reynolds number the two jets are distinct, while for low Reynolds number the two jets combine into a single continuous jet. We also measured the emergence time, speed, and position of the ejecta sheet and found simple scaling relations for these quantities.

Atmospheric Response to Zonal Variations in Midlatitude SST: Transient and Stationary Eddies and Their Feedback(.

NASA Astrophysics Data System (ADS)

Inatsu, Masaru; Mukougawa, Hitoshi; Xie, Shang-Ping

2003-10-01

Midwinter storm track response to zonal variations in midlatitude sea surface temperatures (SSTs) has been investigated using an atmospheric general circulation model under aquaplanet and perpetual-January conditions. Zonal wavenumber-1 SST variations with a meridionally confined structure are placed at various latitudes. Having these SST variations centered at 30°N leads to a zonally localized storm track, while the storm track becomes nearly zonally uniform when the same SST forcing is moved farther north at 40° and 50°N. Large (small) baroclinic energy conversion north of the warm (cold) SST anomaly near the axis of the storm track (near 40°N) is responsible for the large (small) storm growth. The equatorward transfer of eddy kinetic energy by the ageostrophic motion and the mechanical damping are important to diminish the storm track activity in the zonal direction.Significant stationary eddies form in the upper troposphere, with a ridge (trough) northeast of the warm (cold) SST anomaly at 30°N. Heat and vorticity budget analyses indicate that zonally localized condensational heating in the storm track is the major cause for these stationary eddies, which in turn exert a positive feedback to maintain the localized storm track by strengthening the vertical shear near the surface. These results indicate an active role of synoptic eddies in inducing deep, tropospheric-scale response to midlatitude SST variations. Finally, the application of the model results to the real atmosphere is discussed.

Investigating Wave Structures in Jupiter's Atmosphere using HST Images

NASA Astrophysics Data System (ADS)

Johnson, Perianne; Morales-Juberias, Raul; Simon, Amy A.; Wong, Michael H.; Tollefson, Joshua

2016-10-01

Hubble Space Telescope images taken in 2015 and 2016 as part of the Outer Planet Atmosphere Legacy (OPAL) program are used to create zonal wind profiles for Jupiter's atmosphere. These jet profiles are then analyzed for longitudinal variations in latitude or velocity, which can be indicators of wave features in the atmosphere. To create the zonal wind profiles, two image sections, separated in time by Δt (typically about one jovian rotation), are correlated at every latitude from -80° to +80°, and the physical displacement Δx between features in each image is found. This yields a velocity for each latitude. The image sections have dimensions of 80° latitude by 80° longitude, but smaller longitude bins were used in the correlations. That allows each velocity profile to be specific to one longitudinal region on the planet. Variations between profiles thus represent variations in the jet's velocity with longitude. This analysis was performed on images taken in visible wavelengths with HST. Here, we focus on two latitudinal regions, ~17°N and ~7°S, which are locations of prominent westward and eastward jets, respectively. At ~17°N, we find a dichotomy in wind speeds: from 165° to 300°W the wind speeds are roughly -13 m/s, in stark contrast with the -23 m/s velocities measured at all other longitudes. In the 7°S jet, we observe quasi-periodic behavior, with longitude regions alternating between ~148 m/s and ~154 m/s, which is possibly related to chevron activity in the region. With a velocity resolution of a few m/s, we argue that the variations in both jets are significant, and suggest possible wave-related explanations for their existence. This research was supported by the NASA EPSCoR JIVE in NM project awarded to NMSU and NMT and a New Mexico Space Grant awarded to NMT.

Arctic Amplification and the Northward shift of a new Greenland melting record

NASA Astrophysics Data System (ADS)

Tedesco, Marco; Mote, Thomas; Fettweis, Xavier; Hanna, Edward; Booth, James; Jeyaratnam, Jeyavinoth; Datta, Rajashree; Briggs, Kate

2016-04-01

Large-scale atmospheric circulation controls the mass and energy balance of the Greenland ice sheet through its impact on radiative budget, runoff and accumulation. Using reanalysis data and the outputs of a regional climate model, here we show that the persistence of an exceptional atmospheric ridge, centred over the Arctic Ocean was responsible for a northward shift of surface melting records over Greenland, and for increased accumulation in the south during the summer of 2015. Concurrently, new records of mean monthly zonal winds at 500 hPa and of the maximum latitude of ridge peaks of the 5700±50 m isohypse over the Arctic were also set. An unprecedented (1948 - 2015) and sustained jet stream easterly flow promoted enhanced runoff, increased surface temperatures and decreased albedo in northern Greenland, while inhibiting melting in the south. The exceptional 2015 summer Arctic atmospheric conditions are consistent with the anticipated effects of Arctic Amplification, including slower zonal winds and increased jet stream wave amplitude. Properly addressing the impact of Arctic Amplification on surface runoff of the Greenland ice sheet is crucial for rigorously quantifying its contribution to current and future sea level rise, and the relative impact of freshwater discharge on the surrounding ocean.

Gravity Waves in the Atmosphere: Instability, Saturation, and Transport.

DTIC Science & Technology

1995-11-13

role of gravity wave drag in the extratropical QBO , destabilization of large-scale tropical waves by deep moist convection, and a general theory of equatorial inertial instability on a zonally nonuniform, nonparallel flow.

The Aqua-planet Experiment (APE): Response to Changed Meridional SST Profile

NASA Technical Reports Server (NTRS)

Williamson, David L.; Blackburn, Michael; Nakajima, Kensuke; Ohfuchi, Wataru; Takahashi, Yoshiyuki O.; Hayashi, Yoshi-Yuki; Nakamura, Hisashi; Ishiwatari, Masaki; Mcgregor, John L.; Borth, Hartmut;

Jet-images — deep learning edition

DOE PAGES

de Oliveira, Luke; Kagan, Michael; Mackey, Lester; ...

2016-07-13

Building on the notion of a particle physics detector as a camera and the collimated streams of high energy particles, or jets, it measures as an image, we investigate the potential of machine learning techniques based on deep learning architectures to identify highly boosted W bosons. Modern deep learning algorithms trained on jet images can out-perform standard physically-motivated feature driven approaches to jet tagging. We develop techniques for visualizing how these features are learned by the network and what additional information is used to improve performance. Finally, this interplay between physically-motivated feature driven tools and supervised learning algorithms is generalmore » and can be used to significantly increase the sensitivity to discover new particles and new forces, and gain a deeper understanding of the physics within jets.« less

Jet-images — deep learning edition

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Oliveira, Luke; Kagan, Michael; Mackey, Lester

Building on the notion of a particle physics detector as a camera and the collimated streams of high energy particles, or jets, it measures as an image, we investigate the potential of machine learning techniques based on deep learning architectures to identify highly boosted W bosons. Modern deep learning algorithms trained on jet images can out-perform standard physically-motivated feature driven approaches to jet tagging. We develop techniques for visualizing how these features are learned by the network and what additional information is used to improve performance. Finally, this interplay between physically-motivated feature driven tools and supervised learning algorithms is generalmore » and can be used to significantly increase the sensitivity to discover new particles and new forces, and gain a deeper understanding of the physics within jets.« less

Red Spot Movie

NASA Technical Reports Server (NTRS)

2000-01-01

This brief movie shows counterclockwise atmospheric motion around Jupiter's Great Red Spot. The clip was made from blue-filter images taken with the narrow-angle camera on NASA's Cassini spacecraft during seven separate rotations of Jupiter between Oct. 1 and Oct. 5, 2000.

The clip also shows the eastward and westward motion of the zonal jets, seen as the horizontal stripes flowing in opposite directions. The zonal jets circle the planet. As far as can be determined from both Earth-based and spacecraft measurements, the positions and speeds of the jets have not changed for 100 years. Since Jupiter is a fluid planet without a solid boundary, the jet speeds are measured relative to Jupiter's magnetic field, which rotates, wobbling like a top because of its tilt, every 9 hours 55.5 minutes. The movie shows motions in the magnetic reference frame, so winds to the west correspond to features that are rotating a little slower than the magnetic field, and eastward winds correspond to features rotating a little faster.

Because the Red Spot is in the southern hemisphere, the direction of motion indicates it is a high-pressure center. Small bright clouds appear suddenly to the west of the Great Red Spot. Scientists suspect these small white features are lightning storms. The storms eventually merge with the Red Spot and surrounding jets, and may be the main energy source for the large-scale features.

The smallest features in the movie are about 500 kilometers (about 300 miles) across. The spacing of the movie frames in time is not uniform; some consecutive images are separated by two Jupiter rotations, and some by one. The images have been re-projected using a simple cylindrical map projection. They show an area from 50 degrees north of Jupiter's equator to 50 degrees south, extending 100 degrees east-west, about one quarter of Jupiter's circumference.

Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.

A new index for the wintertime southern hemispheric split jet

NASA Astrophysics Data System (ADS)

Babian, Stella; Grieger, Jens; Cubasch, Ulrich

2018-05-01

One of the most prominent asymmetric features of the southern hemispheric (SH) circulation is the split jet over Australia and New Zealand in austral winter. Previous studies have developed indices to detect the degree to which the upper-level midlatitude westerlies are split and investigated the relationship between split events and the low-frequency teleconnection patterns, viz. the Antarctic Oscillation (AAO) and the El Niño-Southern Oscillation (ENSO). As the results were inconsistent, the relationship between the wintertime SH split jet and the climate variability indices remains unresolved and is the focus of this study. Until now, all split indices' definitions were based on the specific region where the split jet is recognizable. We consider the split jet as hemispheric rather than a regional feature and propose a new, hemispherical index that is based on the principal components (PCs) of the zonal wind field for the SH winter. A linear combination of PC2 and PC3 of the anomalous monthly (JAS) zonal wind is used to identify split-jet conditions. In a subsequent correlation analysis, our newly defined PC-based split index (PSI) indicates a strong coherence with the AAO. However, this significant relationship is unstable over the analysis period; during the 1980s, the AAO amplitude was higher than the PSI, and vice versa in the 1990s. It is probable that the PSI, as well as the AAO, underlie low-frequency variability on the decadal to centennial timescales, but the analyzed period is too short to draw these conclusions. A regression analysis with the Multivariate ENSO Index points to a nonlinear relationship between PSI and ENSO; i.e., split jets occur during both strong positive and negative phases of ENSO but rarely under normal conditions. The Pacific South American (PSA) patterns, defined as the second and third modes of the geopotential height variability at 500 hPa, correlate poorly with the PSI (rPSA - 1 ≈ 0.2 and rPSA - 2 = 0.06), but significantly with the individual components (PCs) of the PSI, revealing an indirect influence on the SH split-jet variability. Our study suggests that the wintertime SH split jet is strongly associated with the AAO, while ENSO is to a lesser extent connected to the PSI. We conclude that a positive AAO phase, as well as both flavors of ENSO and the PSA-1 pattern produce favorable conditions for a SH split event.

Observed trends in the global jet stream characteristics during the second half of the 20th century

NASA Astrophysics Data System (ADS)

Pena-Ortiz, Cristina; Gallego, David; Ribera, Pedro; Ordonez, Paulina; Alvarez-Castro, Maria Del Carmen

2013-04-01

In this paper, we propose a new method based on the detection of jet cores with the aim to describe the climatological features of the jet streams and to estimate their trends in latitude, altitude, and velocity in the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) and 20th Century reanalysis data sets. Due to the fact that the detection method uses a single grid point to define the position of jet cores, our results reveal a greater latitudinal definition allowing a more accurate picture of the split flow configurations and double jet structures. To the best of our knowledge, these results provide the first multiseasonal and global trend analysis of jet streams based on a daily-resolution 3-D detection algorithm. Trends have been analyzed over 1958-2008 and during the post-satellite period, 1979-2008. We found that, in general, trends in jet velocities and latitudes have been faster for the Southern Hemisphere jets and especially for the southern polar front jet which has experienced the fastest velocity increase and poleward shift over 1979-2008 during the austral summer and autumn. Results presented here show an acceleration and a poleward shift of the northern and southern winter subtropical jets over 1979-2008 that occur at a faster rate and over larger zonally extended regions during this latter period than during 1958-2008.

Does the vorticity flux from Agulhas rings control the zonal pathway of NADW across the South Atlantic?

NASA Astrophysics Data System (ADS)

van Sebille, Erik; Johns, William E.; Beal, Lisa M.

2012-05-01

As part of the global thermohaline circulation, some North Atlantic Deep Water (NADW) exits the Atlantic basin to the south of Africa. Observations have shown that there is a quasi-zonal pathway centered at 25°S carrying NADW eastward, connecting the Deep Western Boundary Current to the Cape Basin. However, it has been unclear what sets this pathway. In particular, waters must move southward through the Cape Basin, thereby crossing isolines of planetary vorticity, in order to exit the basin. Here, we find that an eddy thickness flux induced by Agulhas rings moving northwestward forces a circulation of NADW through the Cape Basin. The pathway at 25°S feeds the southeastward flow of this circulation while conserving potential vorticity. Using Lagrangian floats advected for 300 years in a 1/10° resolution ocean model, we show that the most common pathway for NADW in our model lies directly below the Agulhas ring corridor. By analyzing the velocity and density fields in the model, we find that the decay of these rings, and their forward tilt with depth, results in a southward velocity, across isolines of planetary vorticity, of 1 to 2 cm/s in the deep waters. The associated stream function pattern yields a deep circulation transporting 4 Sv of NADW from the Deep Western Boundary Current at 25°S to the southern tip of Africa.

Observational evidence of the downstream impact on tropical rainfall from stratospheric Kelvin waves

NASA Astrophysics Data System (ADS)

Zhang, Lei; Karnauskas, Kristopher B.; Weiss, Jeffrey B.; Polvani, Lorenzo M.

2017-08-01

Analysis of one continuous decade of daily, high-vertical resolution sounding data from five proximate islands in the western equatorial Pacific region reveals eastward and downward propagating Kelvin waves in the tropical stratosphere, with a zonal wave number one structure and a period of 15 days. By defining an initiation index, we find that these waves are primarily generated over the western Pacific warm pool and South America-tropical Atlantic sector, consistent with regions of frequent deep convection. The zonal phase speed of the stratospheric Kelvin waves (SKWs) is relatively slow ( 10 m s-1) over the initiation region due to coupling with deep convection, and becomes much faster ( 30-40 m s-1) once decoupled from the downstream troposphere. SKWs have significant impacts on downstream tropical rainfall through modulation of tropopause height. The cold phase of SKWs at tropopause leads to higher tropopause heights and more convection in tropics—with opposite impacts associated with the warm phase. Downstream tropical precipitation anomalies associated with these SKWs also propagate eastward with the same speed and zonal scale as observed SKWs. Interannual variability of the amplitude of the SKWs is shown to be associated with the Quasi-Biennial oscillation (QBO); implications for predictability are discussed.

A PV view of the zonal mean distribution of temperature and wind in the extratropical troposphere

NASA Technical Reports Server (NTRS)

Sun, De-Zheng; Lindzen, Richard S.

1994-01-01

The dependence of the temperature and wind distribution of the zonal mean flow in the extratropical troposphere on the gradient of pontential vorticity along isentropes is examined. The extratropics here refer to the region outside the Hadley circulation. Of particular interest is whether the distribution of temperature and wind corresponding to a constant potential vorticity (PV) along isentropes resembles the observed, and the implications of PV homogenization along isentropes for the role of the tropics. With the assumption that PV is homogenized along isentropes, it is found that the temperature distribution in the extratropical troposphere may be determined by a linear, first-order partial differential equation. When the observed surface temperature distribution and tropical lapse rate are used as the boundary conditions, the solution of the equation is close to the observed temperature distribution except in the upper troposphere adjacent to the Hadley circulation, where the troposphere with no PV gradient is considerably colder. Consequently, the jet is also stronger. It is also found that the meridional distribution of the balanced zonal wind is very sensitive to the meridional distribution of the tropopause temperature. The result may suggest that the requirement of the global momentum balance has no practical role in determining the extratropical temperature distribution. The authors further investigated the sensitivity of the extratropical troposphere with constant PV along isentropes to changes in conditions at the tropical boundary (the edge of the Hadley circulation). It is found that the temperature and wind distributions in the extratropical troposphere are sensitive to the vertical distribution of PV at the tropical boundary. With a surface distribution of temperature that decreases linearly with latitude, the jet maximum occurs at the tropical boundary and moves with it. The overall pattern of wind distribution is not sensitive to the change of the position of the tropical boundary. Finally, the temperature and wind distributions of an extratropical troposphere with a finite PV gradient are calculated. It is found that the larger the isentropic PV gradient, the warmer the troposphere and the weaker the jet.

Effect of dry large-scale vertical motions on initial MJO convective onset

NASA Astrophysics Data System (ADS)

Powell, Scott W.; Houze, Robert A.

2015-05-01

Anomalies of eastward propagating large-scale vertical motion with ~30 day variability at Addu City, Maldives, move into the Indian Ocean from the west and are implicated in Madden-Julian Oscillation (MJO) convective onset. Using ground-based radar and large-scale forcing data derived from a sounding array, typical profiles of environmental heating, moisture sink, vertical motion, moisture advection, and Eulerian moisture tendency are computed for periods prior to those during which deep convection is prevalent and those during which moderately deep cumulonimbi do not form into deep clouds. Convection with 3-7 km tops is ubiquitous but present in greater numbers when tropospheric moistening occurs below 600 hPa. Vertical eddy convergence of moisture in shallow to moderately deep clouds is likely responsible for moistening during a 3-7 day long transition period between suppressed and active MJO conditions, although moistening via evaporation of cloud condensate detrained into the environment of such clouds may also be important. Reduction in large-scale subsidence, associated with a vertical velocity structure that travels with a dry eastward propagating zonal wavenumbers 1-1.5 structure in zonal wind, drives a steepening of the lapse rate below 700 hPa, which supports an increase in moderately deep moist convection. As the moderately deep cumulonimbi moisten the lower troposphere, more deep convection develops, which itself moistens the upper troposphere. Reduction in large-scale subsidence associated with the eastward propagating feature reinforces the upper tropospheric moistening, helping to then rapidly make the environment conducive to formation of large stratiform precipitation regions, whose heating is critical for MJO maintenance.

Atmospheric blocking as a traffic jam in the jet stream

NASA Astrophysics Data System (ADS)

Nakamura, N.; Huang, S. Y.

2017-12-01

It is demonstrated using the ERA-Interim product that synoptic to intraseasonal variabilities of extratropical circulation in the boreal storm track regions are strongly affected by the zonal convergence of the column-integrated eastward flux of local wave activity (LWA). In particular, from the multi-year daily samples of LWA fluxes, we find that the wintertime zonal LWA flux in the jet exit regions tends to maximize for an intermediate value of column-averaged LWA. This is because an increasing LWA decelerates the zonal flow, eventually weakening the eastward advection of LWA. From theory we argue that large wave events on the decreasing side of the flux curve with increasing LWA cannot be maintained as a stable steady state. Consistent with this argument, observed states corresponding to that side of flux curve often exhibit local wave breaking and blocking events. A close parallelism exists for the traffic flow problem, in which the traffic flux (traffic density times traffic speed) is often observed to maximize for an intermediate value of traffic density. This is because the traffic speed is controlled not only by the imposed speed limit but also by the traffic density — an increasingly heavy traffic slows down the flow naturally and eventually decreases the flux. Once the flux starts to decrease with an increasing traffic density, a traffic jam kicks in suddenly (Lighthill and Whitham 1955, Richards 1956). The above idea is demonstrated by a simple conceptual model based on the equivalent barotropic PV contour design (Nakamura and Huang 2017, JAS), which predicts a threshold of blocking onset. The idea also suggests that the LWA that gives the `flux capacity,' i.e., the maximum LWA flux at a given location, is a useful predictor of local wave breaking/block formation.

Drop impact into a deep pool: vortex shedding and jet formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agbaglah, G.; Thoraval, M. -J.; Thoroddsen, S. T.

2015-02-01

One of the simplest splashing scenarios results from the impact of a single drop on a deep pool. The traditional understanding of this process is that the impact generates an axisymmetric sheet-like jet that later breaks up into secondary droplets. Recently it was shown that even this simplest of scenarios is more complicated than expected because multiple jets can be generated from a single impact event and there are transitions in the multiplicity of jets as the experimental parameters are varied. Here, we use experiments and numerical simulations of a single drop impacting on a deep pool to examine themore » transition from impacts that produce a single jet to those that produce two jets. Using high-speed X-ray imaging methods we show that vortex separation within the drop leads to the formation of a second jet long after the formation of the ejecta sheet. Using numerical simulations we develop a phase diagram for this transition and show that the capillary number is the most appropriate order parameter for the transition.« less

Observation of two-jet production in deep inelastic scattering at HERA

NASA Astrophysics Data System (ADS)

Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Repond, J.; Repond, S.; Stanek, R.; Talaga, R. L.; Thron, J.; Arzarello, F.; Ayad, R.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; D'Auria, S.; Del Papa, C.; Frasconi, F.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Lin, Q.; Lisowski, B.; Maccarrone, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Sartorelli, G.; Timellini, R.; Zamora Garcia, Y.; Zichichi, A.; Bargende, A.; Crittenden, J.; Dabbous, H.; Desch, K.; Diekmann, B.; Doeker, T.; Geerts, M.; Geitz, G.; Gutjahr, B.; Hartmann, H.; Haun, D.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Kramarczyk, S.; Kückes, M.; Mass, A.; Mengel, S.; Mollen, J.; Monaldi, D.; Müsch, H.; Paul, E.; Schattevoy, R.; Schneider, J.-L.; Wedemeyer, R.; Cassidy, A.; Cussans, D. G.; Dyce, N.; Fawcett, H. F.; Foster, B.; Gilmore, R.; Heath, G. P.; Lancaster, M.; Llewellyn, T. J.; Malos, J.; Morgado, C. J. S.; Tapper, R. J.; Wilson, S. S.; Rau, R. R.; Arneodo, M.; Barillari, T.; Schioppa, M.; Susinno, G.; Bernstein, A.; Caldwell, A.; Gialas, I.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Chwastowski, J.; Dwuraźny, A.; Eskreys, A.; Jakubowski, Z.; Niziom̵, B.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Bednarek, B.; Borzemski, P.; Eskreys, K.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Kȩdzierski, T.; Kotański, A.; Przybycień, M.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Coldewey, C.; Dannemann, A.; Drews, G.; Erhard, P.; Flasiński, M.; Fleck, I.; Gläser, R.; Göttlicher, P.; Haas, T.; Hagge, L.; Hain, W.; Hasell, D.; Hultschig, H.; Jahnen, G.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Kötz, U.; Kowalski, H.; Krüger, J.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mainusch, J.; Manczak, O.; Momayezi, M.; Ng, J. S. T.; Nickel, S.; Notz, D.; Park, I. H.; Pösnecker, K.-U.; Rohde, M.; Roldán, J.; Ros, E.; Schneekloth, U.; Schroeder, J.; Schulz, W.; Selonke, F.; Stiliaris, E.; Tscheslog, E.; Tsurugai, T.; Turkot, F.; Vogel, W.; Wolf, G.; Youngman, C.; Grabosch, H. J.; Leich, A.; Meyer, A.; Rethfeldt, C.; Schlenstedt, S.; Barbagli, G.; Francescato, A.; Nuti, M.; Pelfer, P.; Anzivino, G.; Casaccia, R.; De Pasquale, S.; Qian, S.; Votano, L.; Bamberger, A.; Freidhof, A.; Poser, T.; Söldner-Rembold, S.; Theisen, G.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Forbes, J. R.; Jamieson, V. A.; Raine, C.; Saxon, D. H.; Brückmann, H.; Gloth, G.; Holm, U.; Kammerlocher, H.; Krebs, B.; Neumann, T.; Wick, K.; Fürtjes, A.; Kröger, W.; Lohrmann, E.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Seidman, A.; Schott, W.; Terron, J.; Wiik, B. H.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Markou, C.; McQuillan, D.; Miller, D. B.; Mobayyen, M. M.; Prinias, A.; Vorvolakos, A.; Bienz, T.; Kreutzmann, H.; Mallik, U.; McCliment, E.; Roco, M.; Wang, M. Z.; Cloth, P.; Filges, D.; Chen, L.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Barreiro, F.; Cases, G.; Hervás, L.; Labarga, L.; del Peso, J.; de Trocóniz, J. F.; Ikraiam, F.; Mayer, J. K.; Smith, G. R.; Corriveau, F.; Gilkinson, D. J.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Meijer Drees, R.; Mitchell, J. W.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; Ullmann, R.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Y. A.; Kuzmin, V. A.; Kuznetsov, E. N.; Savin, A. A.; Voronin, A. G.; Zotov, N. P.; Bentvelsen, S.; Botje, M.; Dake, A.; Engelen, J.; de Jong, P.; de Kamps, M.; Kooijman, P.; Kruse, A.; van der Lugt, H.; O'Dell, V.; Tenner, A.; Tiecke, H.; Uijterwaal, H.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Yoshida, R.; Bylsma, B.; Durkin, L. S.; Honscheid, K.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Park, S. K.; Romanowski, T. A.; Seidlein, R.; Blair, G. A.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Gingrich, D. M.; Hallam-Baker, P. M.; Harnew, N.; Khatri, T.; Long, K. R.; Luffman, P.; McArthur, I.; Morawitz, P.; Nash, J.; Smith, S. J. P.; Roocroft, N. C.; Wilson, F. F.; Abbiendi, G.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Gasparini, F.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Butterworth, J. M.; Bulmahn, J.; Field, G.; Oh, B. Y.; Whitmore, J.; Contino, U.; D'Agostini, G.; Guida, M.; Iori, M.; Mari, S. M.; Marini, G.; Mattioli, M.; Nigro, A.; Hart, J. C.; McCubbin, N. A.; Prytz, K.; Shah, T. P.; Short, T. L.; Barberis, E.; Cartiglia, N.; Heusch, C.; Hubbard, B.; Leslie, J.; Lockman, W.; O'Shaughnessy, K.; Sadrozinski, H. F.; Seiden, A.; Badura, E.; Biltzinger, J.; Chaves, H.; Rost, M.; Seifert, R. J.; Walenta, A. H.; Weihs, W.; Zech, G.; Dagan, S.; Levy, A.; Zer-Zion, D.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kasai, S.; Kuze, M.; Nagasawa, Y.; Nakao, M.; Okuno, H.; Tokushuku, K.; Watanabe, T.; Yamada, S.; Chiba, M.; Hamatsu, R.; Hirose, T.; Kitamura, S.; Nagayama, S.; Nakamitsu, Y.; Cirio, R.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Bhadra, S.; Brkic, M.; Burow, B. D.; Chlebana, F. S.; Crombie, M. B.; Hartner, G. F.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Prentice, J. D.; Sampson, C. R.; Stairs, G. G.; Teuscher, R. J.; Yoon, T.-S.; Bullock, F. W.; Catterall, C. D.; Giddings, J. C.; Jones, T. W.; Khan, A. M.; Lane, J. B.; Makkar, P. L.; Shaw, D.; Shulman, J.; Blankenship, K.; Gibaut, D. B.; Kochocki, J.; Lu, B.; Mo, L. W.; Charchum̵a, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Stopczyński, A.; Tymieniecka, T.; Walczak, R.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Abramowicz, H.; Eisenberg, Y.; Glasman, C.; Karshon, U.; Montag, A.; Revel, D.; Shapira, A.; Foudas, C.; Fordham, C.; Loveless, R. J.; Goussiou, A.; Ali, I.; Behrens, B.; Dasu, S.; Reeder, D. D.; Smith, W. H.; Silverstein, S.; Frisken, W. R.; Furutani, K. M.; Iga, Y.; ZEUS Collaboration

1993-05-01

A sample of events with two distinct jets, in addition to the proton remnant, has been identified in deep inelastic, neutral current ep interactions recorded at HERA by the ZEUS experiment. For these events, the mass of the hadronic system ranges from 40 to 260 GeV. The salient features of the observed jet production agree with the predictions of higher order QCD.

Deep learning in color: towards automated quark/gluon jet discrimination

DOE PAGES

Komiske, Patrick T.; Metodiev, Eric M.; Schwartz, Matthew D.

2017-01-25

Artificial intelligence offers the potential to automate challenging data-processing tasks in collider physics. Here, to establish its prospects, we explore to what extent deep learning with convolutional neural networks can discriminate quark and gluon jets better than observables designed by physicists. Our approach builds upon the paradigm that a jet can be treated as an image, with intensity given by the local calorimeter deposits. We supplement this construction by adding color to the images, with red, green and blue intensities given by the transverse momentum in charged particles, transverse momentum in neutral particles, and pixel-level charged particle counts. Overall, themore » deep networks match or outperform traditional jet variables. We also find that, while various simulations produce different quark and gluon jets, the neural networks are surprisingly insensitive to these differences, similar to traditional observables. This suggests that the networks can extract robust physical information from imperfect simulations.« less

Deep learning in color: towards automated quark/gluon jet discrimination

NASA Astrophysics Data System (ADS)

Komiske, Patrick T.; Metodiev, Eric M.; Schwartz, Matthew D.

2017-01-01

Artificial intelligence offers the potential to automate challenging data-processing tasks in collider physics. To establish its prospects, we explore to what extent deep learning with convolutional neural networks can discriminate quark and gluon jets better than observables designed by physicists. Our approach builds upon the paradigm that a jet can be treated as an image, with intensity given by the local calorimeter deposits. We supplement this construction by adding color to the images, with red, green and blue intensities given by the transverse momentum in charged particles, transverse momentum in neutral particles, and pixel-level charged particle counts. Overall, the deep networks match or outperform traditional jet variables. We also find that, while various simulations produce different quark and gluon jets, the neural networks are surprisingly insensitive to these differences, similar to traditional observables. This suggests that the networks can extract robust physical information from imperfect simulations.

Deep learning in color: towards automated quark/gluon jet discrimination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komiske, Patrick T.; Metodiev, Eric M.; Schwartz, Matthew D.

Artificial intelligence offers the potential to automate challenging data-processing tasks in collider physics. Here, to establish its prospects, we explore to what extent deep learning with convolutional neural networks can discriminate quark and gluon jets better than observables designed by physicists. Our approach builds upon the paradigm that a jet can be treated as an image, with intensity given by the local calorimeter deposits. We supplement this construction by adding color to the images, with red, green and blue intensities given by the transverse momentum in charged particles, transverse momentum in neutral particles, and pixel-level charged particle counts. Overall, themore » deep networks match or outperform traditional jet variables. We also find that, while various simulations produce different quark and gluon jets, the neural networks are surprisingly insensitive to these differences, similar to traditional observables. This suggests that the networks can extract robust physical information from imperfect simulations.« less

JUPITER WILL BECOME A HOT JUPITER: CONSEQUENCES OF POST-MAIN-SEQUENCE STELLAR EVOLUTION ON GAS GIANT PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spiegel, David S.; Madhusudhan, Nikku, E-mail: dave@ias.edu, E-mail: Nikku.Madhusudhan@yale.edu

When the Sun ascends the red giant branch (RGB), its luminosity will increase and all the planets will receive much greater irradiation than they do now. Jupiter, in particular, might end up more highly irradiated than the hot Neptune GJ 436b and, hence, could appropriately be termed a 'hot Jupiter'. When their stars go through the RGB or asymptotic giant branch stages, many of the currently known Jupiter-mass planets in several-AU orbits will receive levels of irradiation comparable to the hot Jupiters, which will transiently increase their atmospheric temperatures to {approx}1000 K or more. Furthermore, massive planets around post-main-sequence starsmore » could accrete a non-negligible amount of material from the enhanced stellar winds, thereby significantly altering their atmospheric chemistry as well as causing a significant accretion luminosity during the epochs of most intense stellar mass loss. Future generations of infrared observatories might be able to probe the thermal and chemical structure of such hot Jupiters' atmospheres. Finally, we argue that, unlike their main-sequence analogs (whose zonal winds are thought to be organized in only a few broad, planetary-scale jets), red-giant hot Jupiters should have multiple, narrow jets of zonal winds and efficient day-night redistribution.« less

The subtropical mesospheric jet observed by the Nimbus 7 Limb Infrared Monitor of the Stratosphere

NASA Technical Reports Server (NTRS)

Dunkerton, T. J.; Delisi, D. P.

1985-01-01

Nimbus 7 Limb Infrared Monitor of the Stratosphere observations of wave-mean flow interactions in the winter 1978-1979 middle atmosphere are surveyed, extending up to 0.05 mbar. These observations describe the evolution of the subtropical mesospheric jet and its polar mixed layer. Quasi-steady mean wind patterns are disrupted by three transitions in this winter: one primarily affecting the mesosphere (December 15, 1978), a minor warming affecting both regions (January 26-February 8, 1979), and a major warming largely confined to the stratosphere (February 22, 1979). The zonally averaged flow is barotropically unstable in the wings of the subtropical mesospheric jet. All the major decelerations of the mean flow are correlated with D(F), the body force per unit mass directly attributable to planetary Rossby waves, indicating that these waves make a significant contribution to the momentum budget in the lower half of the mesosphere.

The role of planetary waves in the tropospheric jet response to stratospheric cooling

NASA Astrophysics Data System (ADS)

Smith, Karen L.; Scott, Richard K.

2016-03-01

An idealized general circulation model is used to assess the importance of planetary-scale waves in determining the position of the tropospheric jet, specifically its tendency to shift poleward as winter stratospheric cooling is increased. Full model integrations are compared against integrations in which planetary waves are truncated in the zonal direction, and only synoptic-scale waves are retained. Two series of truncated integrations are considered, using (i) a modified radiative equilibrium temperature or (ii) a nudged-bias correction technique. Both produce tropospheric climatologies that are similar to the full model when stratospheric cooling is weak. When stratospheric cooling is increased, the results indicate that the interaction between planetary- and synoptic-scale waves plays an important role in determining the structure of the tropospheric mean flow and rule out the possibility that the jet shift occurs purely as a response to changes in the planetary- or synoptic-scale wave fields alone.

[3T magnetic resonance T2 mapping for evaluation of cartilage repair after matrix-associated autologous chondrocyte transplantation].

PubMed

Zhang, Jun; Xu, Xian; Li, Xue; Chen, Min; Dong, Tian-Ming; Zuo, Pan-Li; An, Ning-Yu

2015-01-01

To assess the value of magnetic resonance imaging (MRI) T2 mapping in quantitative evaluation of cartilage repair following matrix-associated autologous chondrocyte transplantation (MACT). Six patients (with 9 plug cartilages) following MACT underwent MRI on a 3.0 Tesla MR scan system at 3, 6 and 12 months after the surgery. The full-thickness and zonal areas (deep and superficial layers) T2 values were calculated for the repaired cartilage and control cartilage. The mean T2 values of the repaired cartilage after MACT were significantly higher than that of the control cartilages at 3 and 6 months (P<0.05), but not at 12 months (P=0.063). At 6 and 12 months, the T2 values of the superficial layers were significantly higher than those of the deep layers in the repaired cartilages (P<0.05). The zonal (deep and superficial layers) T2 values of the repaired cartilages decreased significantly over time at 6 and 12 months as compared to those at 3 months after the surgery (P<0.05). MRI T2 mapping can serve as an important modality for assessing the repair of the articular cartilage following MACT.

Utilizing the Upcoming Gravity Measurements from Cassini's Proximal Orbits for Studying the Atmospheric Dynamics of Saturn - How Deep Do the Winds Penetrate?

NASA Astrophysics Data System (ADS)

Kaspi, Y.; Galanti, E.

2014-12-01

At the end of the Cassini mission, the spacecraft will descend into close-by proximal orbits around Saturn. During those proximal orbits, Cassini will obtain high precision gravity measurements of the planet. In this talk, we will discuss how this data can be used to estimate the depth of the observed flows on the planet. This can be done in several ways: 1. measurements of the high order even harmonics which beyond J10 are dominated by the dynamics; 2. measurements of odd gravity harmonics which have no contribution from a static planet, and therefore are a pure signature of dynamics; 3. upper limits on the depth can be obtained by comparing low order even harmonics from dynamical models to the difference between the measured low order even harmonics and the largest possible values of a static planet; 4. direct latitudinally varying measurements of the gravity field exerted on the spacecraft. We will discuss how these methods may be applied and show that given the expected sensitivity of Cassini the odd harmonics J3 and J5 will have the best sensitivity to deep dynamics, allowing detection of winds reaching only O(100km) deep, if those exist on Saturn. We use a hierarchy of dynamical models ranging from full 3D dynamical circulation models to simplified dynamical models where the sensitivity of the gravity field to the dynamics can be explored. In order to invert the gravity field to be measured by Cassini into the depth dependent circulation, an adjoint inverse model is constructed for the dynamical models, thus allowing backward integration of the dynamical model. This tool can be used for examination of various scenarios, including cases in which the depth of the wind depends on latitudinal position. In summary, we expect that the very end of Cassini's tour holds an opportunity for gravity measurements that may finally allow answering one of the long-lasting puzzles in planetary science regarding the depth of the zonal jets on the gas giants. In fact, as Juno will be performing similar measurements we hope to be able to build a picture of the dynamics for both Jupiter and Saturn. Answering this puzzle, will likely help explain the origin of the multiple jet streams and strong equatorial superrotation on the gas giants.

Modeling Study of Planetary Waves in the Mesosphere Lower Thermosphere (MLT)

NASA Technical Reports Server (NTRS)

Mengel, J. G.; Mayr, H. g.; Drob, D.; Porter, H. S.; Hines, C. O.

2003-01-01

For comparison with measurements from the TIMED satellite and coordinated ground based observations, we present results from our Numerical Spectral Model (NSM) that incorporates the Doppler Spread Parameterization (Hines, 1997) for small-scale gravity waves (GWs). We discuss the planetary waves (PWs) that are purely generated by dynamical interactions, i.e., without explicitly specifying excitation sources related for example to tropospheric convection or topography. With tropospheric heating that reproduces the observed zonal jets near the tropopause and the accompanying reversal in the latitudinal temperature variation, which is conducive to baroclinic instability, long period PWs are produced that propagate up into the stratosphere to affect the wave driven equatorial oscillations (QBO and SAO) extending into the upper mesosphere. The PWs in the model that dominate higher up in the MLT region, however, are to a large extent produced by instabilities under the influence of the zonal circulation and temperature variations in the middle atmosphere and they are amplified by GW interactions. Three classes of PWs are generated there. (1) Rossby waves that slowly propagate westward but are carried by the zonal mean (m = 0) winds to produce eastward and westward propagating PWs respectively in the winter and summer hemispheres below 80 km. Depending on the zonal wave number and magnitudes of the zonal winds under the influence of the equatorial oscillations, the PWs typically have periods between 2 and 20 days and their horizontal wind amplitudes can exceed 40 m/s in the lower mesosphere. (2) Rossby gravity waves that propagate westward at low latitudes, having periods around 2 days for zonal wave numbers m = 2 to 4. (3) Eastward propagating equatorial Kelvin waves generated in the upper mesosphere with periods between 2 and 3 days for m = 1 & 2. The seasonal variations of the PWs reveal that the largest wind amplitudes tend to occur below 80 km in the winter hemisphere, but above that altitude in the summer hemisphere to approach magnitudes as large as 50 m/s.

A new general circulation model of Jupiter's atmosphere based on the UKMO Unified Model: Three-dimensional evolution of isolated vortices and zonal jets in mid-latitudes

NASA Astrophysics Data System (ADS)

Yamazaki, Y. H.; Skeet, D. R.; Read, P. L.

2004-04-01

We have been developing a new three-dimensional general circulation model for the stratosphere and troposphere of Jupiter based on the dynamical core of a portable version of the Unified Model of the UK Meteorological Office. Being one of the leading terrestrial GCMs, employed for operational weather forecasting and climate research, the Unified Model has been thoroughly tested and performance tuned for both vector and parallel computers. It is formulated as a generalized form of the standard primitive equations to handle a thick atmosphere, using a scaled pressure as the vertical coordinate. It is able to accurately simulate the dynamics of a three-dimensional fully compressible atmosphere on the whole or a part of a spherical shell at high spatial resolution in all three directions. Using the current version of the GCM, we examine the characteristics of the Jovian winds in idealized configurations based on the observed vertical structure of temperature. Our initial focus is on the evolution of isolated eddies in the mid-latitudes. Following a brief theoretical investigation of the vertical structure of the atmosphere, limited-area cyclic channel domains are used to numerically investigate the nonlinear evolution of the mid-latitude winds. First, the evolution of deep and shallow cyclones and anticyclones are tested in the atmosphere at rest to identify a preferred horizontal and vertical structure of the vortices. Then, the dependency of the migration characteristics of the vortices are investigated against modelling parameters to find that it is most sensitive to the horizontal diffusion. We also examine the hydrodynamical stability of observed subtropical jets in both northern and southern hemispheres in the three-dimensional nonlinear model as initial value problems. In both cases, it was found that the prominent jets are unstable at various scales and that vorteces of various sizes are generated including those comparable to the White Ovals and the Great Red Spot.

Initial results from SKiYMET meteor radar at Thumba (8.5°N, 77°E): 1. Comparison of wind measurements with MF spaced antenna radar system

NASA Astrophysics Data System (ADS)

Kumar, Karanam Kishore; Ramkumar, Geetha; Shelbi, S. T.

2007-12-01

In the present communication, initial results from the allSKy interferometric METeor (SKiYMET) radar installed at Thumba (8.5°N, 77°E) are presented. The meteor radar system provides hourly zonal and meridional winds in the mesosphere lower thermosphere (MLT) region. The meteor radar measured zonal and meridional winds are compared with nearby MF radar at Tirunalveli (8.7°N, 77.8°E). The present study provided an opportunity to compare the winds measured by the two different techniques, namely, interferometry and spaced antenna drift methods. Simultaneous wind measurements for a total number of 273 days during September 2004 to May 2005 are compared. The comparison showed a very good agreement between these two techniques in the height region 82-90 km and poor agreement above this height region. In general, the zonal winds compare very well as compared to the meridional winds. The observed discrepancies in the wind comparison above 90 km are discussed in the light of existing limitations of both the radars. The detailed analysis revealed the consistency of the measured winds by both the techniques. However, the discrepancies are observed at higher altitudes and are attributed to the contamination of MF radar neutral wind measurements with Equatorial Electro Jet (EEJ) induced inospheric drifts rather than the limitations of the spaced antenna technique. The comparison of diurnal variation of zonal winds above 90 km measured by both the radars is in reasonably good agreement in the absence of EEJ (during local nighttime). It is also been noted that the difference in the zonal wind measurements by both the radars is directly related to the strength of EEJ, which is a noteworthy result from the present study.

An investigation of a super-Earth exoplanet with a greenhouse-gas atmosphere using a general circulation model

NASA Astrophysics Data System (ADS)

Zalucha, Angela M.; Michaels, Timothy I.; Madhusudhan, Nikku

2013-11-01

We use the Massachusetts Institute of Technology general circulation model (GCM) dynamical core, in conjunction with a Newtonian relaxation scheme that relaxes to a gray, analytical solution of the radiative transfer equation, to simulate a tidally locked, synchronously orbiting super-Earth exoplanet. This hypothetical exoplanet is simulated under the following main assumptions: (1) the size, mass, and orbital characteristics of GJ 1214b (Charbonneau, D. [2009]. Nature 462, 891-894), (2) a greenhouse-gas dominated atmosphere, (3), the gas properties of water vapor, and (4) a surface. We have performed a parameter sweep over global mean surface pressure (0.1, 1, 10, and 100 bar) and global mean surface albedo (0.1, 0.4, and 0.7). Given assumption (1) above, the period of rotation of this exoplanet is 1.58 Earth-days, which we classify as the rapidly rotating regime. Our parameter sweep differs from Heng and Vogt (Heng, K., Vogt, S.S. [2011]. Mon. Not. R. Astron. Soc. 415, 2145-2157), who performed their study in the slowly rotating regime and using Held and Suarez (Held, I.M., Suarez, M.J. [1994]. Bull. Am. Meteorol. Soc. 75 (10), 1825-1830) thermal forcing. This type of thermal forcing is a prescribed function, not related to any radiative transfer, used to benchmark Earth’s atmosphere. An equatorial, westerly, superrotating jet is a robust feature in our GCM results. This equatorial jet is westerly at all longitudes. At high latitudes, the flow is easterly. The zonal winds do show a change with global mean surface pressure. As global mean surface pressure increases, the speed of the equatorial jet decreases between 9 and 15 h local time (substellar point is located at 12 h local time). The latitudinal extent of the equatorial jet increases on the nightside. For the two greatest initial surface pressure cases, an increasingly westerly component of flow develops at middle to high latitudes between 11 and 18 h local time. On the nightside, the easterly flow in the midlatitudes also increases in speed as global mean surface pressure increases. Furthermore, the zonal wind speed in the equatorial and midlatitude jets decreases with increasing surface albedo. Also, the latitudinal width of the equatorial jet decreases as surface albedo increases.

Annular Mode Dynamics: Eddy Feedbacks and the Underlying Mechanisms

NASA Astrophysics Data System (ADS)

Hassanzadeh, P.; Ma, D.; Kuang, Z.

2017-12-01

Annular modes are the leading modes the extratropical circulation variability in both hemispheres on intraseasonal to interannual timescales. Temporal persistence and an equivalent-barotropic dipolar wind anomaly are the key spatio-temporal characteristics of the annular modes. The potential source(s) of this persistence, and in particular, whether there is a contribution from a positive eddy-jet feedback, are still unclear (e.g., Lorenz and Hartmann, 2001; Byrne et al., 2016). The mechanism of this feedback, and how it depends on processes such as surface friction, is also not well understood (e.g., Robinson, 2000; Gerber et al., 2007). In this study, we utilize the recently calculated Linear Response Function (LRF) of an idealized GCM (Hassanzadeh and Kuang, 2016). The LRF enables us to accurately calculate the response of eddy momentum/heat fluxes to the zonal-mean zonal wind and temperature anomalies of the annular mode. Using this information: 1) We confirm the existence of a positive eddy-jet feedback in the annular mode of the idealized GCM and accurately quantify the magnitude of this feedback; 2) We quantify the contribution of key processes (e.g., eddy momentum/heat fluxes and surface friction) to the annular mode dynamics in the idealized GCM. We show that as proposed by Robinson (2000), the baroclinic component of the annular mode and surface friction are essential for the positive eddy-jet feedback. Results show that this feedback increases the persistence of the annular mode by a factor of two. We also show that the barotropic component of the annular mode alone does not lead to persistence. In fact, the eddy-jet feedback for the barotropic component is negative because of the dominance of the barotropic governor effect. 3) Using the results of 1, we evaluate the underlying assumptions and accuracy of the statistical methods previously developed for quantifying the eddy-jet feedback (Lorenz and Hartmann, 2001; Simpson et al., 2013) and introduce a new statistical method that shows superior accuracy. We apply the new method to reanalysis data to quantify the eddy-jet feedback for the Southern Annular Mode. The key findings of 1-3 and their implications for our understanding of the annular mode dynamics will be discussed in this presentation.

Two applications of potential vorticity thinking

NASA Technical Reports Server (NTRS)

Robinson, Walter A.

1987-01-01

The phenomena of dissipative destabilization of external Rossby waves and the acceleration of the zonal mean jet during baroclinic life cycles are described in terms of potential vorticity. The main principle of the potential temperature variations at rigid boundaries have the same effect on the interior flow as do sheets of potential vorticity located just within the boundaries. It is noted that the potential vorticity theory is useful for understanding the dynamical behavior of meterological phenomena.

Shape, zonal winds and gravitational field of Jupiter: a fully self-consistent, multi-layered model

NASA Astrophysics Data System (ADS)

Schubert, Gerald; Kong, Dali; Zhang, Keke

2016-10-01

We construct a three-dimensional, finite-element, fully self-consistent, multi-layered,non-spheroidal model of Jupiter consisting of an inner core, a metallic electrically conducting dynamo region and an outer molecular electrically insulating envelope. We assume that the Jovian zonal winds are on cylinders parallel to the rotation axis but, due to the effect of magnetic braking, are confined within the outer molecular envelope. Two related calculations are carried out. The first provides an accurate description of the shape and internal density profile of Jupiter; the effect of rotational distortion is not treated as a small perturbation on a spherically symmetric state. This calculation determines the density, size and shape of the inner core, the irregular shape of the 1-bar pressure level, and the internal structure of Jupiter; the full effect of rotational distortion, without the influence of the zonal winds, is accounted for. Our multi-layered model is able to produce the known mass, the known equatorial and polar radii, and the known zonal gravitational coefficient J2 of Jupiter within their error bars; it also yields the coefficients J4 and J6 within about 5% accuracy, and the core equatorial radius 0.09RJ containing 3.73 Earth masses.The second calculation determines the variation of the gravitational field caused solely by the effect of the zonal winds on the rotationally distorted non-spheroidal Jupiter. Four different cases, ranging from a deep wind profile to a very shallow profile, are considered and implications for accurate interpretation of the zonal gravitational coefficients expected from the Juno mission are discussed.

A joint numerical and experimental study of the jet of an aircraft engine installation with advanced techniques

NASA Astrophysics Data System (ADS)

Brunet, V.; Molton, P.; Bézard, H.; Deck, S.; Jacquin, L.

2012-01-01

This paper describes the results obtained during the European Union JEDI (JEt Development Investigations) project carried out in cooperation between ONERA and Airbus. The aim of these studies was first to acquire a complete database of a modern-type engine jet installation set under a wall-to-wall swept wing in various transonic flow conditions. Interactions between the engine jet, the pylon, and the wing were studied thanks to ¤advanced¥ measurement techniques. In parallel, accurate Reynolds-averaged Navier Stokes (RANS) simulations were carried out from simple ones with the Spalart Allmaras model to more complex ones like the DRSM-SSG (Differential Reynolds Stress Modef of Speziale Sarkar Gatski) turbulence model. In the end, Zonal-Detached Eddy Simulations (Z-DES) were also performed to compare different simulation techniques. All numerical results are accurately validated thanks to the experimental database acquired in parallel. This complete and complex study of modern civil aircraft engine installation allowed many upgrades in understanding and simulation methods to be obtained. Furthermore, a setup for engine jet installation studies has been validated for possible future works in the S3Ch transonic research wind-tunnel. The main conclusions are summed up in this paper.

Nonstationary Gravity Wave Forcing of the Stratospheric Zonal Mean Wind

NASA Technical Reports Server (NTRS)

Alexander, M. J.; Rosenlof, K. H.

1996-01-01

The role of gravity wave forcing in the zonal mean circulation of the stratosphere is discussed. Starting from some very simple assumptions about the momentum flux spectrum of nonstationary (non-zero phase speed) waves at forcing levels in the troposphere, a linear model is used to calculate wave propagation through climatological zonal mean winds at solstice seasons. As the wave amplitudes exceed their stable limits, a saturation criterion is imposed to account for nonlinear wave breakdown effects, and the resulting vertical gradient in the wave momentum flux is then used to estimate the mean flow forcing per unit mass. Evidence from global, assimilated data sets are used to constrain these forcing estimates. The results suggest the gravity-wave-driven force is accelerative (has the same sign as the mean wind) throughout most of the stratosphere above 20 km. The sense of the gravity wave forcing in the stratosphere is thus opposite to that in the mesosphere, where gravity wave drag is widely believed to play a principal role in decelerating the mesospheric jets. The forcing estimates are further compared to existing gravity wave parameterizations for the same climatological zonal mean conditions. Substantial disagreement is evident in the stratosphere, and we discuss the reasons for the disagreement. The results suggest limits on typical gravity wave amplitudes near source levels in the troposphere at solstice seasons. The gravity wave forcing in the stratosphere appears to have a substantial effect on lower stratospheric temperatures during southern hemisphere summer and thus may be relevant to climate.

Modeling Study of Mesospheric Planetary Waves: Genesis and Characteristics

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Mengel, J. G.; Talaat, E. L.; Porter, H. S.; Chan, K. L.

2003-01-01

In preparation for the measurements from the TIMED mission and coordinated ground based observations, we discuss results for the planetary waves (PWs) that appear in our Numerical Spectral Model (NSM). The present model accounts for a tropospheric heat source in the zonal mean (m = 0), which reproduces qualitatively the observed zonal jets near the tropopause and the accompanying reversal in the latitudinal temperature variations. We discuss the PWs that are solely generated internally, i.e., without the explicit excitation sources related to tropospheric convection or topography. Our analysis shows that PWs are not produced when the zonally averaged heat source into the atmosphere is artificially suppressed, and that the PWs generally are significantly weaker when the tropospheric source is not applied. Instabilities associated with the zonal mean temperature, pressure and wind fields, which still need to be explored, are exciting PWs that have amplitudes in the mesosphere comparable to those observed. Three classes of PWs are generated in the NSM. (1) Rossby waves, (2) Rossby gravity waves propagating westward at low latitudes, and (3) Eastward propagating equatorial Kelvin waves. A survey of the PWs reveals that the largest wind amplitudes tend to occur below 80 km in the winter hemisphere, but above that altitude they occur in the summer hemisphere where the amplitudes can approach 50 meters per second. It is shown that the non-migrating tides in the mesosphere, generated by non-linear coupling between migrating tides and PWs, are significantly larger for the model with the tropospheric heat source.

Equatorial Winds on Saturn and the Stratospheric Oscillation

NASA Technical Reports Server (NTRS)

Li, Liming; Jian, Xun; Ingersoll, Andrew P.; DelGenio, Anthony D.; Porco, Carolyn C.; West, Robert A.; Vasavada, Ashwin R.; Ewald, Shawn P.; Conrath, Barney J.; Gierasch, Peter J.;

Influence of an Internally-Generated QBO on Modeled Stratospheric Dynamics and Ozone

NASA Technical Reports Server (NTRS)

Hurwitz, M. M.; Newman, P. A.; Song, I. S.

2011-01-01

A GEOS V2 CCM simulation with an internally generated quasi-biennial oscillation (QBO) signal is compared to an otherwise identical simulation without a QBO. In a present-day climate, inclusion of the modeled QBO makes a significant difference to stratospheric dynamics and ozone throughout the year. The QBO enhances variability in the tropics, as expected, but also in the polar stratosphere in some seasons. The modeled QBO also affects the mean stratospheric climate. Because tropical zonal winds in the baseline simulation are generally easterly, there is a relative increase in zonal wind magnitudes in tropical lower and middle stratosphere in the QBO simulation. Extra-tropical differences between the QBO and 'no QBO' simulations thus reflect a bias toward the westerly phase of the QBO: a relative strengthening and poleward shifting the polar stratospheric jets, and a reduction in Arctic lower stratospheric ozone.

FAR-TECH's Nanoparticle Plasma Jet System and its Application to Disruptions, Deep Fueling, and Diagnostics

NASA Astrophysics Data System (ADS)

Thompson, J. R.; Bogatu, I. N.; Galkin, S. A.; Kim, J. S.

2012-10-01

Hyper-velocity plasma jets have potential applications in tokamaks for disruption mitigation, deep fueling and diagnostics. Pulsed power based solid-state sources and plasma accelerators offer advantages of rapid response and mass delivery at high velocities. Fast response is critical for some disruption mitigation scenario needs, while high velocity is especially important for penetration into tokamak plasma and its confining magnetic field, as in the case of deep fueling. FAR-TECH is developing the capability of producing large-mass hyper-velocity plasma jets. The prototype solid-state source has produced: 1) >8.4 mg of H2 gas only, and 2) >25 mg of H2 and >180 mg of C60 in a H2/C60 gas mixture. Using a coaxial plasma gun coupled to the source, we have successfully demonstrated the acceleration of composite H/C60 plasma jets, with momentum as high as 0.6 g.km/s, and containing an estimated C60 mass of ˜75 mg. We present the status of FAR-TECH's nanoparticle plasma jet system and discuss its application to disruptions, deep fueling, and diagnostics. A new TiH2/C60 solid-state source capable of generating significantly higher quantities of H2 and C60 in <0.5 ms will be discussed.

Climatic Change and Dynamics of Northern Hemisphere Storm-tracks: Changes in Transient Eddies Behavior

NASA Astrophysics Data System (ADS)

Martynova, Yuliya; Krupchatnikov, Vladimir

2013-04-01

An evidence of our understanding of the general circulation is whether we can predict changes in the general circulation that might be associated with past or future climate changes. Changes in the location, intensity or seasonality of major climatological features of the general circulation could be more important than average temperature changes, particularly where these changes could affect local hydrology, energy balances, etc. Under these major climatological features we assume the poleward expansion of the tropical circulation (Hadley circulation), static stability (changes in the vertical temperature structure of the atmosphere), role of SST forcing, sea ice extension, extratropical eddies behavior. We have a question: would the climate change significantly affect the location and intensity of midlatitude storm-tracks and associated jets? Mean-flow interaction in midlatitudes produces low-frequency variations in the latitude of the jets. It is reasonable to think that a modest climate change might significantly affects the jets location and their associated storm tracks. The storm-tracks are defined as the region of strong baroclinicity (maximum meridional temperature gradient), which are determined on the basis of eddy statistics like eddy fluxes of angular momentum, energy, and water (with the use of high-bandpass filter). In the Northern Hemisphere, there are two major storms: in the region of Atlantic and Pacific. The storm-tracks play important role in the dynamics of weather and climate. They affect the global energy cycle and the hydrological cycle, and as a result they bring heavy rains and other hazardous weather phenomena in the middle latitudes. The recent increase in global tropopause heights is closely associated with systematic temperature changes below and above the tropopause. Temperature increases in the troposphere and decreases in the stratosphere. The pattern of warming and cooling also affects the zonal wind structure in the region of the subtropical upper troposphere and lower stratosphere (UTLS). Extratropical tropospheric eddies play a central role in this mechanism. The eddies tend to move eastward with the zonal flow and equatorward toward the subtropics until they reach their critical latitudes, where their phase speed equals the speed of the background zonal flow. This work is partially supported by the Ministry of education and science of the Russian Federation (con-tract #8345), SB RAS project VIII.80.2.1, RFBR grant #11-05-01190a, and integrated project SB RAS #131.

Long-Term Evolution of the Aerosol Debris Cloud Produced by the 2009 Impact on Jupiter

NASA Technical Reports Server (NTRS)

Sanchez-Lavega, A.; Orton, G. S.; Hueso, R.; Perez-Hoyos, S.; Fletcher, L. N.; Garcia-Melendo, E.; Gomez-Forrellad, J. M.; de Pater, I.; Wong, M.; Hammel. H. B.;

Multi-Scale Distributed Representation for Deep Learning and its Application to b-Jet Tagging

NASA Astrophysics Data System (ADS)

Lee, Jason Sang Hun; Park, Inkyu; Park, Sangnam

2018-06-01

Recently machine learning algorithms based on deep layered artificial neural networks (DNNs) have been applied to a wide variety of high energy physics problems such as jet tagging or event classification. We explore a simple but effective preprocessing step which transforms each realvalued observational quantity or input feature into a binary number with a fixed number of digits. Each binary digit represents the quantity or magnitude in different scales. We have shown that this approach improves the performance of DNNs significantly for some specific tasks without any further complication in feature engineering. We apply this multi-scale distributed binary representation to deep learning on b-jet tagging using daughter particles' momenta and vertex information.

Association of whale sharks (Rhincodon typus) with thermo-biological frontal systems of the eastern tropical Pacific.

PubMed

Ryan, John P; Green, Jonathan R; Espinoza, Eduardo; Hearn, Alex R

2017-01-01

Satellite tracking of 27 whale sharks in the eastern tropical Pacific, examined in relation to environmental data, indicates preferential occupancy of thermo-biological frontal systems. In these systems, thermal gradients are caused by wind-forced circulation and mixing, and biological gradients are caused by associated nutrient enrichment and enhanced primary productivity. Two of the frontal systems result from upwelling, driven by divergence in the current systems along the equator and the west coast of South America; the third results from wind jet dynamics off Central America. All whale sharks were tagged near Darwin Island, Galápagos, within the equatorial Pacific upwelling system. Occupancy of frontal habitat is pronounced in synoptic patterns of shark locations in relation to serpentine, temporally varying thermal fronts across a zonal expanse > 4000 km. 80% of shark positions in northern equatorial upwelling habitat and 100% of positions in eastern boundary upwelling habitat were located within the upwelling front. Analysis of equatorial shark locations relative to thermal gradients reveals occupancy of a transition point in environmental stability. Equatorial subsurface tag data show residence in shallow, warm (>22°C) water 94% of the time. Surface zonal current speeds for all equatorial tracking explain only 16% of the variance in shark zonal movement speeds, indicating that passive drifting is not a primary determinant of movement patterns. Movement from equatorial to eastern boundary frontal zones occurred during boreal winter, when equatorial upwelling weakens seasonally. Off Peru sharks tracked upwelling frontal positions within ~100-350 km from the coast. Off Central America, the largest tagged shark (12.8 m TL) occupied an oceanic front along the periphery of the Panama wind jet. Seasonal movement from waning equatorial upwelling to productive eastern boundary habitat is consistent with underlying trophic dynamics. Persistent shallow residence in thermo-biological frontal zones suggests the role of physical-biological interactions that concentrate food resources.

Association of whale sharks (Rhincodon typus) with thermo-biological frontal systems of the eastern tropical Pacific

PubMed Central

Green, Jonathan R.; Espinoza, Eduardo; Hearn, Alex R.

2017-01-01

Satellite tracking of 27 whale sharks in the eastern tropical Pacific, examined in relation to environmental data, indicates preferential occupancy of thermo-biological frontal systems. In these systems, thermal gradients are caused by wind-forced circulation and mixing, and biological gradients are caused by associated nutrient enrichment and enhanced primary productivity. Two of the frontal systems result from upwelling, driven by divergence in the current systems along the equator and the west coast of South America; the third results from wind jet dynamics off Central America. All whale sharks were tagged near Darwin Island, Galápagos, within the equatorial Pacific upwelling system. Occupancy of frontal habitat is pronounced in synoptic patterns of shark locations in relation to serpentine, temporally varying thermal fronts across a zonal expanse > 4000 km. 80% of shark positions in northern equatorial upwelling habitat and 100% of positions in eastern boundary upwelling habitat were located within the upwelling front. Analysis of equatorial shark locations relative to thermal gradients reveals occupancy of a transition point in environmental stability. Equatorial subsurface tag data show residence in shallow, warm (>22°C) water 94% of the time. Surface zonal current speeds for all equatorial tracking explain only 16% of the variance in shark zonal movement speeds, indicating that passive drifting is not a primary determinant of movement patterns. Movement from equatorial to eastern boundary frontal zones occurred during boreal winter, when equatorial upwelling weakens seasonally. Off Peru sharks tracked upwelling frontal positions within ~100–350 km from the coast. Off Central America, the largest tagged shark (12.8 m TL) occupied an oceanic front along the periphery of the Panama wind jet. Seasonal movement from waning equatorial upwelling to productive eastern boundary habitat is consistent with underlying trophic dynamics. Persistent shallow residence in thermo-biological frontal zones suggests the role of physical-biological interactions that concentrate food resources. PMID:28854201

Numerical simulation of the interaction between a flowfield and chemical reaction on premixed pulsed jet combustion

NASA Astrophysics Data System (ADS)

Hishida, Manabu; Hayashi, A. Koichi

1992-12-01

Pulsed Jet Combustion (PJC) is numerically simulated using time-dependent, axisymmetric, full Navier-Stokes equations with the mass, momentum, energy, and species conservation equations for a hydrogen-air mixture. A hydrogen-air reaction mechanism is modeled by nine species and nineteen elementary forward and backward reactions to evaluate the effect of the chemical reactions accurately. A point implicit method with the Harten and Yee's non-MUSCL (Monotone Upstream-centerd Schemes for Conservation Laws) modified-flux type TVD (Total Variation Diminishing) scheme is applied to deal with the stiff partial differential equations. Furthermore, a zonal method making use of the Fortified Solution Algorithm (FSA) is applied to simulate the phenomena in the complicated shape of the sub-chamber. The numerical result shows that flames propagating in the sub-chamber interact with pressure waves and are deformed to be wrinkled like a 'tulip' flame and a jet passed through the orifice changes its mass flux quasi-periodically.

Arctic-midlatitude weather linkages in North America

NASA Astrophysics Data System (ADS)

Overland, James E.; Wang, Muyin

2018-06-01

There is intense public interest in whether major Arctic changes can and will impact midlatitude weather such as cold air outbreaks on the central and east side of continents. Although there is progress in linkage research for eastern Asia, a clear gap is conformation for North America. We show two stationary temperature/geopotential height patterns where warmer Arctic temperatures have reinforced existing tropospheric jet stream wave amplitudes over North America: a Greenland/Baffin Block pattern during December 2010 and an Alaska Ridge pattern during December 2017. Even with continuing Arctic warming over the past decade, other recent eastern US winter months were less susceptible for an Arctic linkage: the jet stream was represented by either zonal flow, progressive weather systems, or unfavorable phasing of the long wave pattern. The present analysis lays the scientific controversy over the validity of linkages to the inherent intermittency of jet stream dynamics, which provides only an occasional bridge between Arctic thermodynamic forcing and extended midlatitude weather events.

Orography and the Boreal Winter Stratosphere: The Importance of the Mongolian Mountains

NASA Astrophysics Data System (ADS)

White, R. H.; Battisti, D. S.; Sheshadri, A.

2018-02-01

The impact of mountains on stratospheric circulation is explored using the Whole Atmosphere Community Climate Model. The "Mongolian mountains" decrease the boreal winter stratospheric jet strength by ˜1/3 and increase the frequency of major sudden stratospheric warmings from 0.08 year-1 to the observed 0.60 year-1. These changes are twice the magnitude of the impacts of the Tibetan plateau and Himalayas. Consistent with the decrease in the zonal jet, there is enhanced Eliassen-Palm flux convergence; this is predominantly from changes in wave propagation pathways through changes to the upper troposphere circulation, not from an increased amplitude of planetary waves reaching the stratosphere. The Mongolian mountains have the greater impact on upper tropospheric circulation due to their meridional location. The Rocky Mountains have no significant impact on the stratospheric jet. Changes in wave propagation in response to the Mongolian mountains are similar to those associated with major sudden stratospheric warming events in observations.

Convection and Dynamo Action in Ice Giant Dynamo Models with Electrical Conductivity Stratification

NASA Astrophysics Data System (ADS)

Soderlund, K. M.; Featherstone, N. A.; Heimpel, M. H.; Aurnou, J. M.

2017-12-01

Uranus and Neptune are relatively unexplored, yet critical for understanding the physical and chemical processes that control the behavior and evolution of giant planets. Because their multipolar magnetic fields, three-jet zonal winds, and extreme energy balances are distinct from other planets in our Solar System, the ice giants provide a unique opportunity to test hypotheses for internal dynamics and magnetic field generation. While it is generally agreed that dynamo action in the ionic ocean generates their magnetic fields, the mechanisms that control the morphology, strength, and evolution of the dynamos - which are likely distinct from those in the gas giants and terrestrial planets - are not well understood. We hypothesize that the dynamos and zonal winds are dynamically coupled and argue that their characteristics are a consequence of quasi-three-dimensional turbulence in their interiors. Here, we will present new dynamo simulations with an inner electrically conducting region and outer electrically insulating layer to self-consistently couple the ionic oceans and molecular envelopes of these planets. For each simulation, the magnetic field morphology and amplitude, zonal flow profile, and internal heat flux pattern will be compared against corresponding observations of Uranus and Neptune. We will also highlight how these simulations will both contribute to and benefit from a future ice giant mission.

Mie lidar and radiosonde observations at Gadanki (13.5°N, 79.2°E) during sudden stratospheric warming of 2009

NASA Astrophysics Data System (ADS)

Sridharan, S.; Raghunath, K.; Sathishkumar, S.; Nath, D.

2011-03-01

During a major sudden stratospheric warming event (21-27 January 2009), Mie-lidar observations at Gadanki (13.5°N, 79.2°E) show persistent occurrence of cirrus clouds. Outgoing long-wave radiation averaged for 70°E-90°E, decreases to a low value (170 W/m2) on 27 January 2009 over equator indicating deep convection. The zonal mean ERA-Interim data reveal large northward and upward circulation over equatorial upper troposphere. The latitude-longitude map of ERA-Interim zonal mean potential vorticity (PV) indicates two tongues of high PV emanating from polar latitudes and extending further down to equator. Radiosonde observations at Gadanki show the presence of ∼40% relative humidity at 11-13 km and lower tropopause temperature. It is inferred that the tropical circulation change due to PV intrusion leads to deep convection, which along with high humidity and low tropopause temperature leading to the formation of persistent cirrus clouds, the occurrence frequency of which is normally less during winter season over Gadanki.

Single-Inclusive Jet Production In Electron-Nucleon Collisions Through Next-To-Next-To-Leading Order In Perturbative QCD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abelof, Gabriel; Boughezal, Radja; Liu, Xiaohui

2016-10-17

We compute the Oσ 2σ 2 s perturbative corrections to inclusive jet production in electron-nucleon collisions. This process is of particular interest to the physics program of a future Electron Ion Collider (EIC). We include all relevant partonic processes, including deep-inelastic scattering contributions, photon-initiated corrections, and parton-parton scattering terms that first appear at this order. Upon integration over the final-state hadronic phase space we validate our results for the deep-inelastic corrections against the known next-to-next-to-leading order (NNLO) structure functions. Our calculation uses the N-jettiness subtraction scheme for performing higher-order computations, and allows for a completely differential description of the deep-inelasticmore » scattering process. We describe the application of this method to inclusive jet production in detail, and present phenomenological results for the proposed EIC. The NNLO corrections have a non-trivial dependence on the jet kinematics and arise from an intricate interplay between all contributing partonic channels.« less

The dynamical core of the Aeolus 1.0 statistical-dynamical atmosphere model: validation and parameter optimization

NASA Astrophysics Data System (ADS)

Totz, Sonja; Eliseev, Alexey V.; Petri, Stefan; Flechsig, Michael; Caesar, Levke; Petoukhov, Vladimir; Coumou, Dim

2018-02-01

We present and validate a set of equations for representing the atmosphere's large-scale general circulation in an Earth system model of intermediate complexity (EMIC). These dynamical equations have been implemented in Aeolus 1.0, which is a statistical-dynamical atmosphere model (SDAM) and includes radiative transfer and cloud modules (Coumou et al., 2011; Eliseev et al., 2013). The statistical dynamical approach is computationally efficient and thus enables us to perform climate simulations at multimillennia timescales, which is a prime aim of our model development. Further, this computational efficiency enables us to scan large and high-dimensional parameter space to tune the model parameters, e.g., for sensitivity studies.Here, we present novel equations for the large-scale zonal-mean wind as well as those for planetary waves. Together with synoptic parameterization (as presented by Coumou et al., 2011), these form the mathematical description of the dynamical core of Aeolus 1.0.We optimize the dynamical core parameter values by tuning all relevant dynamical fields to ERA-Interim reanalysis data (1983-2009) forcing the dynamical core with prescribed surface temperature, surface humidity and cumulus cloud fraction. We test the model's performance in reproducing the seasonal cycle and the influence of the El Niño-Southern Oscillation (ENSO). We use a simulated annealing optimization algorithm, which approximates the global minimum of a high-dimensional function.With non-tuned parameter values, the model performs reasonably in terms of its representation of zonal-mean circulation, planetary waves and storm tracks. The simulated annealing optimization improves in particular the model's representation of the Northern Hemisphere jet stream and storm tracks as well as the Hadley circulation.The regions of high azonal wind velocities (planetary waves) are accurately captured for all validation experiments. The zonal-mean zonal wind and the integrated lower troposphere mass flux show good results in particular in the Northern Hemisphere. In the Southern Hemisphere, the model tends to produce too-weak zonal-mean zonal winds and a too-narrow Hadley circulation. We discuss possible reasons for these model biases as well as planned future model improvements and applications.

Subtropical Potential Vorticity Intrusion Drives Increasing Tropospheric Ozone over the Tropical Central Pacific.

PubMed

Nath, Debashis; Chen, Wen; Graf, Hans-F; Lan, Xiaoqing; Gong, Hainan; Nath, Reshmita; Hu, Kaiming; Wang, Lin

2016-02-12

Drawn from multiple reanalysis datasets, an increasing trend and westward shift in the number of Potential Vorticity intrusion events over the Pacific are evident. The increased frequency can be linked to a long-term trend in upper tropospheric equatorial westerly wind and subtropical jets during boreal winter to spring. These may be resulting from anomalous warming and cooling over the western Pacific warm pool and the tropical eastern Pacific, respectively. The intrusions brought dry and ozone rich air of stratospheric origin deep into the tropics. In the tropical upper troposphere, interannual ozone variability is mainly related to convection associated with El Niño/Southern Oscillation. Zonal mean stratospheric overturning circulation organizes the transport of ozone rich air poleward and downward to the high and midlatitudes leading there to higher ozone concentration. In addition to these well described mechanisms, we observe a long-term increasing trend in ozone flux over the northern hemispheric outer tropical (10-25°N) central Pacific that results from equatorward transport and downward mixing from the midlatitude upper troposphere and lower stratosphere during PV intrusions. This increase in tropospheric ozone flux over the Pacific Ocean may affect the radiative processes and changes the budget of atmospheric hydroxyl radicals.

Modulation of frontogenetic plankton production along a meandering jet by zonal wind forcing: An application to the Alboran Sea

NASA Astrophysics Data System (ADS)

Oguz, Temel; Mourre, Baptiste; Tintoré, Joaquin

2017-08-01

We present a coupled physical-biological modeling study to elucidate the changes in ageostrophic frontal dynamics and the frontogenetic plankton production characteristics of a meandering jet under the impacts of successive westerly/easterly wind events combined with seasonal variations in the upstream transport and buoyancy flux characteristics of the jet, using a case study for the Alboran Sea (Western Mediterranean). Their nonlinear coupling is shown to result in different forms of physical and biological characteristics of the background jet structure that follows a meandering path around two anticyclonic gyres in the western and eastern basins and a cyclonic eddy in between. The westerly, downfront wind events broaden the jet, and result in stronger cross-frontal density contrast and intensify ageostrophic cross-frontal secondary circulation. Thus, they improve the frontogenetic plankton production with respect to the no-wind case. They also support higher production along the northern coast in response to wind-induced coastal upwelling and spreading of resulting nutrient-rich, productive water by mesoscale stirring. These features weaken gradually as the jet transport reduces. In contrast, stronger and longer-lasting easterlies during the reduced jet transport phase weaken the currents and frontal density structure, change the circular Western Alboran Gyre to an elongated form, and shift the main axis of the jet towards the southern basin. Then, frontogenesis fails to contribute to phytoplankton production that becomes limited to the eddy pumping within cyclones. Apart from the frontogenetic production, eddy pumping, mesoscale stirring, and diapycnal mixing of nutrients support intermittent and localized phytoplankton patches over the basin.

The stratopause semiannual oscillation in the NCAR Community Climate Model

NASA Technical Reports Server (NTRS)

Sassi, Fabrizio; Garcia, Roland R.; Boville, Byron A.

1993-01-01

The middle atmospheric version of the NCAR Community Climate Model (CCM2) has been used to study the development of the equatorial semiannual oscillation (SAO) in the stratosphere. The model domain extends from the ground to about 80 km, with a vertical resolution of 1 km. Transport of nitrous oxide (N2O) with simplified photochemistry is included in the calculation to illustrate the influence of tropical circulations on the distribution of trace species. Diagnosis of model output reveals two distinct phases in the evolution of the zonal mean state on the equator. In early December, a strong and broad easterly jet appears near the stratopause in connection with a midlatitude wave event (sudden stratospheric warming) that reverses the winter westerlies of the Northern Hemisphere throughout the upper stratosphere. When the wave forcing dies out, the radiative drive allows the westerlies to recover at midlatitudes, while easterlies persist in the tropics. The resulting strong meridional gradient of the zonal mean wind provides favorable conditions for the development of inertial instability at lower latitudes. The meridional circulation associated with the instability shapes the 'nose' of the easterly jet, reducing the extension of the unstable region. In equinoctial conditions, a jet of westerlies appears in the lower equatorial mesosphere and descends to lower altitudes; positive accelerations associated with the descending westerlies are due primarily to Kelvin waves. The descent of the westerly jet does not reproduce well the observed behavior of the SAO westerly phase, either in amplitude or in the extent of downward propagation. As a consequence, the model does not simulate the 'double peak' observed in the tropical distribution of N2O. Comparison of wave amplitudes in the model with those derived from satellite observations shows that the calculated amplitudes are larger than observed in the upper stratosphere. It follows that inadequate Kelvin wave forcing is not the cause of the weak westerly phase in the model, and that some other mechanism must be responsible for the generation of the strong westerly phase observed.

Jets in Planetary Atmospheres

NASA Astrophysics Data System (ADS)

Dowling, Tim

2018-05-01

Jet streams, "jets" for short, are remarkably coherent streams of air found in every major atmosphere. They have a profound effect on a planet's global circulation, and have been an enigma since the belts and zones of Jupiter were discovered in the 1600s. The study of jets, including what processes affect their size, strength, direction, shear stability, and predictability, are active areas of research in geophysical fluid dynamics. Jet research is multidisciplinary and global, involving collaborations between observers, experimentalists, numerical modelers, and applied mathematicians. Jets in atmospheres have strong analogies with shear instability in nonneutral plasmas, and these connections are highlighted throughout the article. The article begins with a description of four major challenges that jet researchers face: nonlinearity, non-intuitive wave physics, non-constant-coefficients, and copious nondimensional numbers. Then, two general fluid-dynamical tenets, the practice of rendering expressions dimensionally homogeneous (nondimensional), and the universal properties of shocks are applied to the open question of what controls the on-off switch of shear instability. The discussion progresses to how the physics of jets varies in equatorial, midlatitude, and polar regions, and how jets are observed to behave in each of these settings. The all-in-one conservation law of potential vorticity (PV), which combines the conservation laws of mass, momentum, and thermal energy into a single expression, is the common language of jet research. Earth and Uranus have weak retrograde equatorial jets, but most planets exhibit super-rotating equatorial jets, which require eddies to transport momentum up gradient in a non-intuitive manner. Jupiter and Saturn exhibit multiple alternating jets in their midlatitudes. The theory for why jets are invariably zonal (east-west orientated) is reviewed, and the particular challenges that Jupiter's sharp westward jets present to existing theories and laboratory experiments are discussed. The impressive inhibition of mixing across polar jets is examined; and the transient nature of polar jets on Earth and Mars is contrasted with the permanence of jets on the giant planets, including Saturn's beautiful north-polar hexagon. The article rounds out with a sample of ideas for future research.

Measurement of αs from jet rates in deep inelastic scattering at HERA

NASA Astrophysics Data System (ADS)

Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Repond, J.; Stanek, R.; Talaga, R. L.; Zhang, H.; Ayad, R.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Polini, A.; Sartorelli, G.; Timellini, R.; Zamora Garcia, Y.; Zichichi, A.; Bargende, A.; Bornheim, A.; Crittenden, J.; Desch, K.; Diekmann, B.; Doeker, T.; Eckert, M.; Feld, L.; Frey, A.; Geerts, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mengel, S.; Mollen, J.; Paul, E.; Pfeiffer, M.; Rembser, Ch.; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Cottingham, W. N.; Dyce, N.; Foster, B.; George, S.; Hayes, M. E.; Heath, G. P.; Heath, H. F.; Morgado, C. J. S.; O'Mara, J. A.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Yoshida, R.; Rau, R. R.; Arneodo, M.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Bernstein, A.; Caldwell, A.; Cartiglia, N.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Kotański, A.; Przybycień, M.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Coldewey, C.; Deppe, O.; Desler, K.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Gutjahr, B.; Haas, T.; Hain, W.; Hasell, D.; Heßling, H.; Iga, Y.; Johnson, K. F.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Köpke, L.; Kötz, U.; Kowalski, H.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mainusch, J.; Mańczak, O.; Monteiro, T.; Ng, J. S. T.; Nickel, S.; Notz, D.; Ohrenberg, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Stiliaris, E.; Surrow, B.; Voß, T.; Westphal, D.; Wolf, G.; Youngman, C.; Zeuner, W.; Zhou, J. F.; Grabosch, H. J.; Kharchilava, A.; Leich, A.; Mattingly, M. C. K.; Mari, S. M.; Meyer, A.; Schlenstedt, S.; Wulff, N.; Barbagli, G.; Pelfer, P.; Anzivino, G.; Maccarrone, G.; De Pasquale, S.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Freidhof, A.; Söldner-Rembold, S.; Schroeder, J.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Saxon, D. H.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Neumann, T.; Sinkus, R.; Wick, K.; Badura, E.; Burow, B. D.; Hagge, L.; Lohrmann, E.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Bruemmer, N.; Butterworth, I.; Gallo, E.; Harris, V. L.; Hung, B. Y. H.; Long, K. R.; Miller, D. B.; Morawitz, P. P. O.; Prinias, A.; Sedgbeer, J. K.; Whitfield, A. F.; Mallik, U.; McCliment, E.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; An, S. H.; Hong, S. M.; Nam, S. W.; Park, S. K.; Suh, M. H.; Yon, S. H.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Cases, G.; Fernandez, J. P.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martinez, M.; del Peso, J.; Puga, J.; Terron, J.; de Trocóniz, J. F.; Smith, G. R.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; St. Laurent, M.; Ullmann, R.; Zacek, G.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Yu. A.; Kobrin, V. D.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Botje, M.; Chlebana, F.; Dake, A.; Engelen, J.; de Kamps, M.; Kooijman, P.; Kruse, A.; Tiecke, H.; Verkerke, W.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Honscheid, K.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Nylander, P.; Park, I. H.; Romanowski, T. A.; Seidlein, R.; Bailey, D. S.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Lindemann, L.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Wilson, F. F.; Yip, T.; Abbiendi, G.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Butterworth, J. M.; Feild, R. G.; Oh, B. Y.; Okrasinski, J. R.; Whitmore, J. J.; D'Agostini, G.; Marini, G.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Prytz, K.; Shah, T. P.; Short, T. L.; Barberis, E.; Dubbs, T.; Heusch, C.; Van Hook, M.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Biltzinger, J.; Seifert, R. J.; Schwarzer, O.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Händel-Pikielny, C.; Levy, A.; Fleck, J. I.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kuze, M.; Mine, S.; Nagasawa, Y.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Nakamitsu, Y.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Brkic, M.; Gingrich, D. M.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sampson, C. R.; Teuscher, R. J.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Blankenship, K.; Lu, B.; Mo, L. W.; Bogusz, W.; Charchuła, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Eisenberg, Y.; Karshon, U.; Revel, D.; Zer-Zion, D.; Ali, I.; Badgett, W. F.; Behrens, B.; Dasu, S.; Fordham, C.; Foudas, C.; Goussiou, A.; Loveless, R. J.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Tsurugai, T.; Bhadra, S.; Cardy, M. L.; Fagerstroem, C.-P.; Frisken, W. R.; Furutani, K. M.; Khakzad, M.; Schmidke, W. B.; ZEUS Collaboration

1995-02-01

Jet production in deep inelastic scattering for 120 < Q2 < 3600 GeV 2 has been studied using data from an integrated luminosity of 3.2 pb -1 collected with the ZEUS detector at HERA. Jets are identified with the JADE algorithm. A cut on the angular distribution of parton emission in the γ ∗- parton centre-of-mass system minimises the experimental and theoretical uncertainties in the determination of the jet rates. The jet rates, when compared to O( αs2) perturbative QCD calculations, allow a precise determination of αs( Q) in three Q2-intervals. The values are consistent with a running of ifαs( Q), as expected from QCD. Extrapolating to Q = M Z 0αs( MZ0) = 0.117 ± 0.005 (stat) -0.005+0.004 (syst exp) ± 0.007 (syst theory).

Studies of planetary scale waves and instabilities in support of the geophysical fluid flow cell experiment on USML-2

NASA Technical Reports Server (NTRS)

Hart, J. E.

1995-01-01

High resolution numerical simulations of thermal convection in a rapidly rotating channel with gravity perpendicular to the rotation vector are described. The convecting columns are subject to a beta-effect resulting from cross-channel topographic vortex stretching. The symmetries of the problem allow many invariant wavenumber sets, and this property is associated with the existence of stable multiple-equilibria at modest supercriticality. The transition to chaotic behavior involves the production of intermittent unstable orbits off a two-torus in energy space. At very high Rayleigh number (of order 10(exp 6) to 10(exp 7)) the motion can be turbulent, depending on the size of beta. However, the turbulence is usually characterized by an almost-periodic formation of patches of small scale convection that cause regular pulsations in the accompanying strong zonal jets. The processes maintaining these flows may be related to those responsible for the zonal currents on Jupiter and for cyclic variability on the Sun.

Role of upper-level wind shear on the structure and maintenance of derecho-producing convective systems

NASA Astrophysics Data System (ADS)

Coniglio, Michael Charles

Common large-scale environments associated with the development of derecho-producing convective systems from a large number of events are identified using statistical clustering of the 500-mb geopotential heights as guidance. The majority of the events (72%) fall into three main patterns that include a well-defined upstream trough (40%), a ridge (20%), and a zonal, low-amplitude flow (12%), which is defined as an additional warm-season pattern that is not identified in past studies of derecho environments. Through an analysis of proximity soundings, discrepancies are found in both low-level and deep-tropospheric shear parameters between observations and the shear profiles considered favorable for strong, long-lived convective systems in idealized simulations. To explore the role of upper-level shear in derecho environments, a set of two-dimensional simulations of density currents within a dry, neutrally stable environment are used to examine the ability of a cold pool to lift environmental air within a vertically sheared flow. The results confirm that the addition of upper-level shear to a wind profile with weak to moderate low-level shear increases the vertical displacement of low-level parcels despite a decrease in the vertical velocity along the cold pool interface, as suggested by previous studies. Parcels that are elevated above the surface (1-2 km) overturn and are responsible for the deep lifting in the deep-shear environments. This deep overturning caused by the upper-level shear helps to maintain the tilt of the convective systems in more complex two-dimensional and three dimensional simulations. The overturning also is shown to greatly increase the size of the convective systems in the three-dimensional simulations by facilitating the initiation and maintenance of convective cells along the cold pool. When combined with estimates of the cold pool motion and the storm-relative hodograph, these results may best be used for the prediction of the demise of strong, linear mesoscale convective systems (MCSs) and may provide a conceptual model for the persistence of strong MCSs above a surface nocturnal inversion in situations that are not forced by a low-level jet.

The North Pacific Summer Jet and Climate Extremes Over North America: Mechanisms and Model Biases

NASA Astrophysics Data System (ADS)

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

2017-12-01

The North Pacific summer jet (NPSJ) plays a critical role as a waveguide for weather systems and other sub-seasonal Rossby waves entering North America and therefore has a controlling influence on the warm season weather and climate extremes over much of the continent. In particular, much of the warm season precipitation that occurs over the central United States depends on subseasonal transients that are able to tap moisture from the Gulf of Mexico as they propagate across the continent. The GEOS-5 atmospheric general circulation model (AGCM), like many AGCMs, is deficient in the simulation of the NPSJ. It is shown that the deficiency is composed of: 1) a stunted jet in which the strongest winds are confined to the Asian continent, failing to extend across the North Pacific into the Gulf of Alaska as observed, and 2) a zonally symmetric poleward shift in the jet. These biases combine to impede the eastward propagation of the weather systems into the continent (the stunted jet), and deprive those systems that do enter the continent access to the moisture from the Gulf (the northward shift), leading to a dry bias over the central US. It is shown that the stunted jet bias is the result of too strong heating that occurs just south of the jet core over and near Tibet. Furthermore, it is shown that the poleward shift of the NPSJ can be corrected in the current GEOS-5 AGCM by increasing the vertical resolution. The implications of these results for improving warm season forecasts of extreme events will be discussed.

Influence of the Tibetan Plateau snow cover on East Asian winter upper-level jet streams at daily time scale

NASA Astrophysics Data System (ADS)

Guo, W.; Li, W.; Qiu, B.; Xue, Y.

2017-12-01

The Tibetan Plateau (TP) acts as an elevated cooling source in the middle troposphere at wintertime. We here present evidence that the intraseasonal variability of the TP snow cover (TPSC) controls part of the East Asian upper-level jet stream. This study found that there is significant positive lag correlation between the East Asian (EA) upper-level westerly jet and the TPSC in winter. When the TPSC increases/decreases, the EA upper-level westerly jet enhances/weakens in the following 8 days. We performed numerical experiments to prove that the lag correlation is causal relationship by using a regional climate model. Due to the high albedo of the snow cover, the increased/decreased snow cover increases/decreases the albedo and affects the surface energy balance over the TP. The energy absorbed by the surface is reduced/increased due to increased/decreased shortwave reflects to the atmosphere. There is anomalous cooling/heating effect over the TP. Such effect leads to anomalous geopotential height (GHT) field that propagates eastward with the zonal wind to the east. The anomalous GHT reaches key region of EA upper-level westerly jet at about 6 days. The adaptive modulation of GHT gradients affects wind fields (through geostrophic balance). As a result, the EA upper-level westerly jet is enhanced (weakened). Through the above process, the TPSC eventually influences the EA upper-level westerly jet. This report reveals that the intraseasonal variability of TPSC can server as an indicator of East Asia Atmospheric circulation on short-to-medium range.

The North Pacific Summer Jet and Climate Extremes over North America: Mechanisms and Model Biases

NASA Technical Reports Server (NTRS)

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

2017-01-01

The North Pacific summer jet (NPSJ) plays a critical role as a waveguide for weather systems and other sub-seasonal Rossby waves entering North America and therefore has a controlling influence on the warm season weather and climate extremes over much of the continent. In particular, much of the warm season precipitation that occurs over the central United States depends on subseasonal transients that are able to tap moisture from the Gulf of Mexico as they propagate across the continent. The GEOS-5 atmospheric general circulation model (AGCM), like many AGCMs, is deficient in the simulation of the NPSJ. It is shown that the deficiency is composed of: 1) a stunted jet in which the strongest winds are confined to the Asian continent, failing to extend across the North Pacific into the Gulf of Alaska as observed, and 2) a zonally symmetric poleward shift in the jet. These biases combine to impede the eastward propagation of the weather systems into the continent (the stunted jet), and deprive those systems that do enter the continent access to the moisture from the Gulf (the northward shift), leading to a dry bias over the central US. It is shown that the stunted jet bias is the result of too strong heating that occurs just south of the jet core over and near Tibet. Furthermore, it is shown that the poleward shift of the NPSJ can be corrected in the current GEOS-5 AGCM by increasing the vertical resolution. The implications of these results for improving warm season forecasts of extreme events will be discussed.

Processed Movie of Zonal Jets

NASA Technical Reports Server (NTRS)

2000-01-01

This movie is a manipulated sequence showing motions in Jupiter's atmosphere over the course of five days beginning Oct. 1, 2000, as seen by a camera on NASA's Cassini spacecraft, using a blue filter.

Beginning with seven images taken at uneven time intervals, this sequence was made by using information on wind speeds derived from actual Jupiter images to create evenly spaced time steps throughout. The final result is a smooth movie sequence consisting of both real and false frames.

The view is of the opposite side of the planet from Jupiter's Great Red Spot. The region shown reaches from 50 degrees north to 50 degrees south of Jupiter's equator, and extends 100 degrees east-to-west, about one-quarter of Jupiter's circumference. The smallest features are about 500 kilometers (about 300 miles) across.

Towards the end of the sequence, a shadow appears from one of Jupiter's moons, Europa.

The movie shows the remains of a historic merger that began several years ago, when three white oval storms that had existed for 60 years merged into two, then one. The resulting oval is visible in the lower left portion of the movie.

The movie also shows zonal jets that circle the planet on constant latitudes. Winds seen moving toward the left (westward) correspond to features that are rotating a little slower than Jupiter's magnetic field, and winds moving the opposite direction correspond to features that are rotating a little faster than the magnetic field. Since Jupiter has no solid surface, the rotation of the magnetic field is the point of reference for the rotation of the planet.

Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.

Meso-beta scale numerical simulation studies of terrain-induced jet streak mass and momentum perturbations

NASA Technical Reports Server (NTRS)

Lin, Yuh-Lang; Kaplan, Michael L.

1994-01-01

An in-depth analysis of observed gravity waves and their relationship to precipitation bands over the Montana mesonetwork during the 11-12 July 1981 CCOPE case study indicated two episodes of coherent waves. While geostrophic adjustment, shearing instability, and terrain were all implicated separately or in combination as possible wave generation mechanisms, the lack of upper-air data within the wave genesis region made it difficult to define the genesis processes from observations alone. The first part of this paper, 3D Numerical Modeling Studies of Terrain-Induced Mass/Momentum Perturbations, employs a mesoscale numerical model to help diagnose the intricate early wave generation mechanisms during the first observed gravity wave episode. The meso-beta scale numerical model is used to study various simulations of the role of multiple geostrophic adjustment processes in focusing a region for gravity wave genesis. The second part of this paper, Linear Theory and Theoretical Modeling, investigates the response of non-resting rotating homogeneous and continuously stratified Boussinesq models of the terrestrial atmosphere to temporally impulsive and uniformly propagating three-dimensional localized zonal momentum sources representative of midlatitude jet streaks. The methods of linear perturbation theory applied to the potential vorticity (PV) and wave field equations are used to study the geostrophic adjustment dynamics. The total zonal and meridional wind perturbations are separated into geostrophic and ageostrophic components in order to define and follow the evolution of both the primary and secondary mesocirculations accompanying midlatitude jetogenesis forced by geostrophic adjustment processes. This problem is addressed to help fill the gap in understanding the dynamics and structure of mesoscale inertia-gravity waves forced by geostrophic adjustment processes in simple two-dimensional quiescent current systems and those produced by mesoscale numerical models simulating the orographic and diabatic perturbation of three-dimensional quasi-geostrophically balanced synoptic scale jet streaks associated with complex baroclinic severe storm producing environments.

Publications of the Jet Propulsion Laboratory, January through December 1974. [deep space network, Apollo project, information theory, and space exploration

NASA Technical Reports Server (NTRS)

1975-01-01

Formalized technical reporting is described and indexed, which resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory. The five classes of publications included are technical reports, technical memorandums, articles from the bimonthly Deep Space Network Progress Report, special publications, and articles published in the open literature. The publications are indexed by author, subject, and publication type and number.

Dynamical Meteorology of the Equatorial and Extratropical Stratosphere

NASA Technical Reports Server (NTRS)

Dunkerton, Tomothy

1999-01-01

Observational studies were performed of westward propagating synoptic scale waves in the tropical troposphere, the structure of monsoon circulations in the upper troposphere and lower stratosphere, and zonally propagating features in deep tropical convection. The effect of the quasi-biennial oscillation (QBO) were investigated, and a numerical study of the QBO was performed using a two-dimensional model, highlighting the role of gravity waves in the momentum balance of the QBO. Vertical coupling of the troposphere and stratosphere was examined in polar regions on intraseasonal and interannual timescales. A deep circumpolar mode was discovered, now known as the Arctic Oscillation.

Shallow water simulations of Saturn's giant storms at different latitudes

NASA Astrophysics Data System (ADS)

García-Melendo, E.; Sánchez-Lavega, A.

2017-04-01

Shallow water simulations are used to present a unified study of three major storms on Saturn (nicknamed as Great White Spots, GWS) at different latitudes, polar (1960), equatorial (1990), and mid-latitude (2010) (Sánchez-Lavega, 2004; Sánchez-Lavega et al., 2011). In our model, the three GWS are initiated by introducing a Gaussian function pulse at the latitude of the observed phenomena with controlled horizontal size and amplitude. This function represents the convective source that has been observed to trigger the storm. A growing disturbance forms when the pulse reacts to ambient winds, expanding zonally along the latitude band of the considered domain. We then compare the modeled potential vorticity with the cloud field, adjusting the model parameters to visually get the closest aspect between simulations and observations. Simulations of the 2010 GWS (planetographic latitude ∼+40º, zonal velocity of the source ∼-30 m s-1) indicate that the Coriolis forces and the wind profile structure shape the disturbance generating, as observed, a long region to the east of the convective source with a high speed peripheral anticyclonic circulation, and a long-lived anticyclonic compact vortex accompanied by strong zonal advection on the southern part of the storm forming a turbulent region. Simulations of the equatorial 1990 GWS (planetographic latitude +12º-+5º, zonal velocity of the source 365-400 m s-1) show a different behavior because of the intense eastward jet, meridional shear at the equatorial region, and low latitude dynamics. A round shaped source forms as observed, with the rapid growth of a Kelvin-Helmholtz instability on the north side of the source due to advection and to the strong meridional wind shear, whereas at the storm latitude the disturbance grows and propagates eastward. The storm nucleus is the manifestation of a Rossby wave, while the eastward propagating planetary-scale disturbance is a gravity-Rossby wave trapped around the equator. The simulated 1960 GWS disturbance (planetographic latitude +56º, zonal velocity 4 m s-1) formed a chain of periodic oval spots that mimic the few available observations of the phenomenon. For the mid and high latitude storms, simulations predict a strong injection of negative relative vorticity due to divergence of the upwelling storm material, which may produce large anticyclones on the anticyclonic side of the zonal profile, and a quick turbulent expansion on the background cyclonic regions. In general, simulations indicate that negative relative vorticity injected by storms determines the natural reaction to zonal winds at latitudes where Coriolis forces are dominant.

Blinded by the Jets

NASA Image and Video Library

2005-07-04

This image shows the view from NASA Deep Impact probe 30 minutes before it was pummeled by comet Tempel 1. The picture brightness has been enhanced to show the jets of dust streaming away from the comet.

The Southern Ocean's role in ocean circulation and climate transients

NASA Astrophysics Data System (ADS)

Thompson, A. F.; Stewart, A.; Hines, S.; Adkins, J. F.

2017-12-01

The ventilation of deep and intermediate density classes at the surface of the Southern Ocean impacts water mass modification and the air-sea exchange of heat and trace gases, which in turn influences the global overturning circulation and Earth's climate. Zonal variability occurs along the Antarctic Circumpolar Current and the Antarctic margins related to flow-topography interactions, variations in surface boundary conditions, and exchange with northern basins. Information about these zonal variations, and their impact on mass and tracer transport, are suppressed when the overturning is depicted as a two-dimensional (depth-latitude) streamfunction. Here we present an idealized, multi-basin, time-dependent circulation model that applies residual circulation theory in the Southern Ocean and allows for zonal water mass transfer between different ocean basins. This model efficiently determines the temporal evolution of the ocean's stratification, ventilation and overturning strength in response to perturbations in the external forcing. With this model we explore the dynamics that lead to transitions in the circulation structure between multiple, isolated cells and a three-dimensional, "figure-of-eight," circulation in which traditional upper and lower cells are interleaved. The transient model is also used to support a mechanistic explanation of the hemispheric asymmetry and phase lag associated with Dansgaard-Oeschger (DO) events during the last glacial period. In particular, the 200 year lag in southern hemisphere temperatures, following a perturbation in North Atlantic deep water formation, depends critically on the migration of Southern Ocean isopycnal outcropping in response to low-latitude stratification changes. Our results provide a self-consistent dynamical framework to explain various ocean overturning transitions that have occurred over the Earth's last 100,000 years, and motivate an exploration of these mechanisms in more sophisticated climate models.

Spacecraft Images Comet Target Jets

NASA Image and Video Library

2010-11-04

NASA Deep Impact spacecraft High- and Medium-Resolution Imagers HRI and MRI captured multiple jets emanating from comet Hartley 2 turning on and off while the spacecraft is 8 million kilometers 5 million miles away from the comet.

Internal waves and Equatorial dynamics: an observational study in the West Atlantic Ocean

NASA Astrophysics Data System (ADS)

Rabitti, Anna; Maas, Leo R. M.; van Haren, Hans; Gerkema, Theo

2013-04-01

Internal waves present several fascinating aspects of great relevance for geo- and astro-physical fluid dynamics. These waves are supported by all kinds of stratified and rotating fluids, such as, for example, our ocean, atmosphere, a planet fluid core or a star. In a non linear regime, because of their oblique propagation, they are thought to play a key role in diapycnal mixing, as well as in angular momentum mixing. Unfortunately, a complete analytical description of internal waves in arbitrarily shaped enclosed domains is still an ongoing challenge. On the other hand, internal wave energy is observed travelling along rays, whose behaviour can be traced and whose reflections off the container's boundaries appears crucial in producing phenomena such as focussing of wave energy onto specific trajectories (attractors), and in triggering localized instabilities. Ray tracing studies have shown that equatorial regions of stratified and/or rotating spherical shells are likely affected by these features, being the place where the simplest shaped and most energetic attractors occur. In this study we aim to investigate the possible presence and role of internal wave attractors in determining the equatorial ocean dynamics. Internal wave attractors, observed in laboratory and numerical experiments, have not been observed in Nature, yet. A unique set of observations, collected in the deep Equatorial West Atlantic Ocean, will be used here in order to explore this possibility, the dataset consisting of 1.5 year long time series of current measured acoustically and with current meters moored between 0°and 2°N, at 37°W, off the Brazilian coast. In particular, angular momentum mixing due to internal wave focussing, is explored as a possible mechanism for maintaining the Equatorial Deep Jets. These jets are stacked alternating zonal currents that are ubiquitously observed in all the oceans and whose nature is still largely unknown. Remarkably, jet like structures are also observed in the equatorial regions of fluid planets, suggesting that their existence could be related to general properties of the system such as shape, stratification and rotation. The equatorial ocean shows a different dynamics compared to off-equatorial regions, in terms of mean flow, internal wave and mixing properties. Despite the crucial role it plays in the global circulation and in our climate, this region is still poorly understood. We propose that the use of a new framework of interpretation, together with long term, in situ measurements can shed some light on the processes taking place in this peculiar region, and constitutes a key step towards a better understanding of energy fluxes in the ocean, as well as in other stratified, rotating fluid domains.

Comparison of the effect of land-sea thermal contrast on interdecadal variations in winter and summer blockings

NASA Astrophysics Data System (ADS)

He, Yongli; Huang, Jianping; Li, Dongdong; Xie, Yongkun; Zhang, Guolong; Qi, Yulei; Wang, Shanshan; Totz, Sonja

2017-11-01

The influence of winter and summer land-sea surface thermal contrast on blocking for 1948-2013 is investigated using observations and the coupled model intercomparison project outputs. The land-sea index (LSI) is defined to measure the changes of zonal asymmetric thermal forcing under global warming. The summer LSI shows a slower increasing trend than winter during this period. For the positive of summer LSI, the EP flux convergence induced by the land-sea thermal forcing in the high latitude becomes weaker than normal, which induces positive anomaly of zonal-mean westerly and double-jet structure. Based on the quasiresonance amplification mechanism, the narrow and reduced westerly tunnel between two jet centers provides a favor environment for more frequent blocking. Composite analysis demonstrates that summer blocking shows an increasing trend of event numbers and a decreasing trend of durations. The numbers of the short-lived blocking persisting for 5-9 days significantly increases and the numbers of the long-lived blocking persisting for longer than 10 days has a weak increase than that in negative phase of summer LSI. The increasing transient wave activities induced by summer LSI is responsible for the decreasing duration of blockings. The increasing blocking due to summer LSI can further strengthen the continent warming and increase the summer LSI, which forms a positive feedback. The opposite dynamical effect of LSI on summer and winter blocking are discussed and found that the LSI-blocking negative feedback partially reduces the influence of the above positive feedback and induce the weak summer warming rate.

Jet production and fragmentation properties in deep inelastic muon scattering

NASA Astrophysics Data System (ADS)

Arneodo, M.; Arvidson, A.; Aubert, J. J.; Badelek, B.; Beaufays, J.; Bee, C. P.; Benchouk, C.; Berghoff, G.; Bird, I.; Blum, D.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S.; Brück, H.; Calen, H.; Chima, J. S.; Ciborowski, J.; Clifft, R.; Coignet, G.; Combley, F.; Conrad, J.; Coughlan, J.; D'Agostini, G.; Dahlgren, S.; Dengler, F.; Derado, I.; Dreyer, T.; Drees, J.; Drobnitzki, M.; Düren, M.; Eckardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Ftàčnik, J.; Gabathuler, E.; Gajewski, J.; Gamet, R.; Gayler, J.; Geddes, N.; Grafström, P.; Grard, F.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Jaffre, M.; Jacholkowska, A.; Janata, F.; Jancso, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, A.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Malecki, P.; Manz, A.; Maselli, S.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Pawlik, B.; Payre, P.; Peroni, C.; Peschel, H.; Pessard, H.; Pettingale, J.; Pietrzyk, B.; Pietrzyk, U.; Pönsgen, B.; Pötsch, M.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Sandacz, A.; Scheer, M.; Schlabböhmer, A.; Schiemann, H.; Schmitz, N.; Schneegans, M.; Scholz, M.; Schröder, T.; Schultze, K.; Sloan, T.; Stier, H. E.; Studt, M.; Taylor, G. N.; Thénard, J. M.; Thompson, J. C.; de La Torre, A.; Toth, J.; Urban, L.; Urban, L.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S. J.; Windmolders, R.; Wolf, G.; Ziemons, K.

1987-12-01

Results are presented from a study of deep inelastic 280 GeV muon-nucleon interactions on the transverse momenta and jet properties of the final state hadrons. The results are analysed in a way which attempts to separate the contributions of hard and soft QCD effects from those that arise from the fragmentation process. The fragmentation models with which the data are compared are the Lund string model, the independent jet model, the QCD parton shower model including soft gluon interference effects, and the firestring model. The discrimination between these models is discussed. Various methods of analysis of the data in terms of hard QCD processes are presented. From a study of the properties of the jet profiles a value of α s , to leading order, is determined using the Lund string model, namely α s =0.29±0.01 (stat.) ±0.02 (syst.), for Q 2˜20 GeV2.

Statistical porcess control in Deep Space Network operation

NASA Technical Reports Server (NTRS)

Hodder, J. A.

2002-01-01

This report describes how the Deep Space Mission System (DSMS) Operations Program Office at the Jet Propulsion Laboratory's (EL) uses Statistical Process Control (SPC) to monitor performance and evaluate initiatives for improving processes on the National Aeronautics and Space Administration's (NASA) Deep Space Network (DSN).

The vertical structure of Jupiter and Saturn zonal winds from nonlinear simulations of major vortices and planetary-scale disturbances

NASA Astrophysics Data System (ADS)

Garcia-Melendo, E.; Legarreta, J.; Sanchez-Lavega, A.

2012-12-01

Direct measurements of the structure of the zonal winds of Jupiter and Saturn below the upper cloud layer are very difficult to retrieve. Except from the vertical profile at a Jupiter hot spot obtained from the Galileo probe in 1995 and measurements from cloud tracking by Cassini instruments just below the upper cloud, no other data are available. We present here our inferences of the vertical structure of Jupiter and Saturn zonal wind across the upper troposphere (deep down to about 10 bar level) obtained from nonlinear simulations using the EPIC code of the stability and interactions of large-scale vortices and planetary-scale disturbances in both planets. Acknowledgements: This work has been funded by Spanish MICIIN AYA2009-10701 with FEDER support, Grupos Gobierno Vasco IT-464-07 and UPV/EHU UFI11/55. [1] García-Melendo E., Sánchez-Lavega A., Dowling T.., Icarus, 176, 272-282 (2005). [2] García-Melendo E., Sánchez-Lavega A., Hueso R., Icarus, 191, 665-677 (2007). [3] Sánchez-Lavega A., et al., Nature, 451, 437- 440 (2008). [4] Sánchez-Lavega A., et al., Nature, 475, 71-74 (2011).

Seasonal Correlations of SST, Water Vapor, and Convective Activity in Tropical Oceans: A New Hyperspectral Data Set for Climate Model Testing

NASA Technical Reports Server (NTRS)

Aumann, Hartmut H.; Gregorich, David T.; Broberg, Steven E.; Elliott, Denis A.

2007-01-01

The analysis of the response of the Earth Climate System to the seasonal changes of solar forcing in the tropical oceans using four years of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) data between 2002 and 2006 gives new insight into amplitude and phase relationships between surface and tropospheric temperatures, humidity, and convective activity. The intensity of the convective activity is measured by counting deep convective clouds. The peaks of convective activity, temperature in the mid-troposphere, and water vapor in the 0 - 30 N and 0 - 30 S tropical ocean zonal means occur about two months after solstice, all leading the peak of the sea surface temperature by several weeks. Phase is key to the evaluation of feedback. The evaluation of climate models in terms of zonal and annual means and annual mean deviations from zonal means can now be supplemented by evaluating the phase of key atmospheric and surface parameters relative to solstice. The ability of climate models to reproduce the statistical flavor of the observed amplitudes and relative phases for broad zonal means should lead to increased confidence in the realism of their water vapor and cloud feedback algorithms. AIRS and AMSU were launched into a 705 km altitude polar sun-synchronous orbit on the EOS Aqua spacecraft on May 4, 2002, and have been in routine data gathering mode since September 2002.

Seasonal Correlations of SST, Water Vapor, and Convective Activity in Tropical Oceans: A New Hyperspectral Data Set for Climate Model Testing

NASA Technical Reports Server (NTRS)

Aumann, Hartmut H.; Gregorich, David T.; Broberg, Steven E.; Elliott, Denis A.

2007-01-01

The analysis of the response of the Earth Climate System to the seasonal changes of solar forcing in the tropical oceans using four years of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) data between 2002 and 2006 gives new insight into amplitude and phase relationships between surface and tropospheric temperatures, humidity, and convective activity. The intensity of the convective activity is measured by counting deep convective clouds. The peaks of convective activity, temperature in the mid-troposphere, and water vapor in the 0-30 N and 0-30 S tropical ocean zonal means occur about two months after solstice, all leading the peak of the sea surface temperature by several weeks. Phase is key to the evaluation of feedback. The evaluation of climate models in terms of zonal and annual means and annual mean deviations from zonal means can now be supplemented by evaluating the phase of key atmospheric and surface parameters relative to solstice. The ability of climate models to reproduce the statistical flavor of the observed amplitudes and relative phases for broad zonal means should lead to increased confidence in the realism of their water vapor and cloud feedback algorithms. AIRS and AMSU were launched into a 705 km altitude polar sun-synchronous orbit on the EOS Aqua spacecraft on May 4, 2002, and have been in routine data gathering mode since September 2002.

Convectively driven decadal zonal accelerations in Earth's fluid core

NASA Astrophysics Data System (ADS)

More, Colin; Dumberry, Mathieu

2018-04-01

Azimuthal accelerations of cylindrical surfaces co-axial with the rotation axis have been inferred to exist in Earth's fluid core on the basis of magnetic field observations and changes in the length-of-day. These accelerations have a typical timescale of decades. However, the physical mechanism causing the accelerations is not well understood. Scaling arguments suggest that the leading order torque averaged over cylindrical surfaces should arise from the Lorentz force. Decadal fluctuations in the magnetic field inside the core, driven by convective flows, could then force decadal changes in the Lorentz torque and generate zonal accelerations. We test this hypothesis by constructing a quasi-geostrophic model of magnetoconvection, with thermally driven flows perturbing a steady, imposed background magnetic field. We show that when the Alfvén number in our model is similar to that in Earth's fluid core, temporal fluctuations in the torque balance are dominated by the Lorentz torque, with the latter generating mean zonal accelerations. Our model reproduces both fast, free Alfvén waves and slow, forced accelerations, with ratios of relative strength and relative timescale similar to those inferred for the Earth's core. The temporal changes in the magnetic field which drive the time-varying Lorentz torque are produced by the underlying convective flows, shearing and advecting the magnetic field on a timescale associated with convective eddies. Our results support the hypothesis that temporal changes in the magnetic field deep inside Earth's fluid core drive the observed decadal zonal accelerations of cylindrical surfaces through the Lorentz torque.

Clouds and the extratropical circulation response to global warming in a hierarchy of global atmosphere models

NASA Astrophysics Data System (ADS)

Voigt, A.

2017-12-01

Climate models project that global warming will lead to substantial changes in extratropical jet streams. Yet, many quantitative aspects of warming-induced jet stream changes remain uncertain, and recent work has indicated an important role of clouds and their radiative interactions. Here, I will investigate how cloud-radiative changes impact the zonal-mean extratropical circulation response under global warming using a hierarchy of global atmosphere models. I will first focus on aquaplanet setups with prescribed sea-surface temperatures (SSTs), which reproduce the model spread found in realistic simulations with interactive SSTs. Simulations with two CMIP5 models MPI-ESM and IPSL-CM5A and prescribed clouds show that half of the circulation response can be attributed to cloud changes. The rise of tropical high-level clouds and the upward and poleward movement of midlatitude high-level clouds lead to poleward jet shifts. High-latitude low-level cloud changes shift the jet poleward in one model but not in the other. The impact of clouds on the jet operates via the atmospheric radiative forcing that is created by the cloud changes and is qualitatively reproduced in a dry Held-Suarez model, although the latter is too sensitive because of its simplified treatment of diabatic processes. I will then show that the aquaplanet results also hold when the models are used in a realistic setup that includes continents and seasonality. I will further juxtapose these prescribed-SST simulations with interactive-SST simulations and show that atmospheric and surface cloud-radiative interactions impact the jet poleward jet shifts in about equal measure. Finally, I will discuss the cloud impact on regional and seasonal circulation changes.

On the Roles of Upper- versus Lower-level Thermal Forcing in Shifting the Eddy-Driven Jet

NASA Astrophysics Data System (ADS)

Zhang, Y.; Nie, Y.; Chen, G.; Yang, X. Q.

2017-12-01

One most drastic atmospheric change in the global warming scenario is the increase in temperature over tropical upper-troposphere and polar surface. The strong warming over those two area alters the spacial distributions of the baroclinicity in the upper-troposphere of subtropics and in the lower-level of subpolar region, with competing effects on the mid-latitude atmospheric circulation. The final destination of the eddy-driven jet in future climate could be "a tug of war" between the impacts of such upper- versus lower-level thermal forcing. In this study, the roles of upper- versus lower-level thermal forcing in shifting the eddy-driven jet are investigated using a nonlinear multi-level quasi-geostrophic channel model. All of our sensitivity experiments show that the latitudinal position of the eddy-driven jet is more sensitive to the upper-level thermal forcing. Such upper-level dominance over the lower-level forcing can be attributed to the different mechanisms through which eddy-driven jet responses to them. The upper-level thermal forcing induces a jet shift mainly by affecting the baroclinic generation of eddies, which supports the latitudinal shift of the eddy momentum flux convergence. The jet response to the lower-level thermal forcing, however, is strongly "eddy dissipation control". The lower-level forcing, by changing the baroclinicity in the lower troposphere, induces a direct thermal zonal wind response in the upper level thus modifies the nonlinear wave breaking and the resultant irreversible eddy mixing, which amplifies the latitudinal shift of the eddy-driven jet. Whether the eddy response is "generation control" or "dissipation control" may strongly depend on the eddy behavior in its baroclinic processes. Only the anomalous eddy generation that penetrates into the upper troposphere can have a striking impact on the eddy momentum flux, which pushes the jet shift more efficiently and dominates the eddy response.

A Numerical Study of Nonlinear Nonhydrostatic Conditional Symmetric Instability in a Convectively Unstable Atmosphere.

NASA Astrophysics Data System (ADS)

Seman, Charles J.

1994-06-01

Nonlinear nonhydrostatic conditional symmetric instability (CSI) is studied as an initial value problem using a two-dimensional (y, z)nonlinear, nonhydrostatic numerical mesoscale/cloud model. The initial atmosphere for the rotating, baroclinic (BCF) simulation contains large convective available potential energy (CAPE). Analytical theory, various model output diagnostics, and a companion nonrotating barotropic (BTNF) simulation are used to interpret the results from the BCF simulation. A single warm moist thermal initiates convection for the two 8-h simulations.The BCF simulation exhibited a very intricate life cycle. Following the initial convection, a series of discrete convective cells developed within a growing mesoscale circulation. Between hours 4 and 8, the circulation grew upscale into a structure resembling that of a squall-line mesoscale convective system (MCS). The mesoscale updrafts were nearly vertical and the circulation was strongest on the baroclinically cool side of the initial convection, as predicted by a two-dimensional Lagrangian parcel model of CSI with CAPE. The cool-side mesoscale circulation grew nearly exponentially over the last 5 h as it slowly propagated toward the warm air. Significant vertical transport of zonal momentum occurred in the (multicellular) convection that developed, resulting in local subgeostrophic zonal wind anomalies aloft. Over time, geostrophic adjustment acted to balance these anomalies. The system became warm core, with mesohigh pressure aloft and mesolow pressure at the surface. A positive zonal wind anomaly also formed downstream from the mesohigh.Analysis of the BCF simulation showed that convective momentum transport played a key role in the evolution of the simulated MCS, in that it fostered the development of the nonlinear CSI on mesoscale time scales. The vertical momentum transport in the initial deep convection generated a subgeostrophic zonal momentum anomaly aloft; the resulting imbalance in pressure gradient and Coriolis forces accelerated the meridional outflow toward the baroclinically cool side, transporting zonal momentum horizontally. The vertical (horizontal) momentum transport occurred on a convective (inertial) time scale. Taken together, the sloping convective updraft/cool side outflow represents the release of the CSI in the convectively unstable atmosphere. Further diagnostics showed that mass transports in the horizontal outflow branch ventilated the upper levels of the system, with enhanced mesoscale lifting in the core and on the leading edge of the MCS, which assisted in convective redevelopments on mesoscale time scales. Geostrophic adjustment acted to balance the convectively generated zonal momentum anomalies, thereby limiting the strength of the meridional outflow predicted by CSI theory. Circulation tendency diagnostics showed that the mesoscale circulation developed in response to thermal wind imbalances generated by the deep convection.Comparison of the BCF and BTNF simulations showed that baroclinicity enhanced mesoscale circulation growth. The BTNF circulation was more transient on mesoscale time and space scales. Overall, the BCF system produced more rainfall than the BTNF.Based on the present and past work in CSI theory, a new definition for the term `slantwise convection' is proposed.

Saturn meteorology - A diagnostic assessment of thin-layer configurations for the zonal flow

NASA Technical Reports Server (NTRS)

Allison, M.; Stone, P. H.

1983-01-01

Voyager imaging, infrared, and radio observations for Saturn have been recently interpreted by Smith et al. (1982) as an indication that the jet streams observed at the cloud tops extend to depths greater than the 10,000-bar level. This analysis assumes a maximum latitudinal temperature contrast of a few percent, a mean atmospheric rotation rate at depth given by Saturn's ratio period, and no variation with latitude of the bottom pressure level for the zonal flow system. These assumptions are not, however, firmly constrained by observation. The diagnostic analysis of plausible alternative configurations for Saturn's atmospheric structure demonstrates that a thin weather layer system (confined at mid to high latitudes to levels above 200 bar) cannot be excluded by any of the available observations. A quantitative estimate of the effects of moisture condensation (including the differentiation of mean molecular weight) suggests that these might provide the buoyancy contrasts necessary to support a thin-layer flow provided that Saturn's outer envelope is enriched approximately 10 times in water abundance relative to a solar composition atmosphere and strongly differentiated with latitude at the condensation level.

Influence of the sudden stratospheric warming on quasi-2-day waves

NASA Astrophysics Data System (ADS)

Gu, Sheng-Yang; Liu, Han-Li; Dou, Xiankang; Li, Tao

2016-04-01

The influence of the sudden stratospheric warming (SSW) on a quasi-2-day wave (QTDW) with westward zonal wave number 3 (W3) is investigated using the Thermosphere-Ionosphere-Mesosphere Electrodynamics General Circulation Model (TIME-GCM). The summer easterly jet below 90 km is strengthened during an SSW, which results in a larger refractive index and thus more favorable conditions for the propagation of W3. In the winter hemisphere, the Eliassen-Palm (EP) flux diagnostics indicate that the strong instabilities at middle and high latitudes in the mesopause region are important for the amplification of W3, which is weakened during SSW periods due to the deceleration or even reversal of the winter westerly winds. Nonlinear interactions between the W3 and the wave number 1 stationary planetary wave produce QTDW with westward zonal wave number 2 (W2). The meridional wind perturbations of the W2 peak in the equatorial region, while the zonal wind and temperature components maximize at middle latitudes. The EP flux diagnostics indicate that the W2 is capable of propagating upward in both winter and summer hemispheres, whereas the propagation of W3 is mostly confined to the summer hemisphere. This characteristic is likely due to the fact that the phase speed of W2 is larger, and therefore its waveguide has a broader latitudinal extension. The larger phase speed also makes W2 less vulnerable to dissipation and critical layer filtering by the background wind when propagating upward.

The solar and equatorial QBO influences on the stratospheric circulation during the early northern-hemisphere winter. [Quasi-Biennial Oscillation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kodera, Kunihiko

1991-06-01

A case study was conducted to investigate the mechanism of how the solar cycle and the equatorial quasi-biennial oscillation (QBO) influence the stratospheric circulation during the Northern-Hemisphere winter. It was found that the solar and QBO influences on the stratospheric jet exist rather independently in the upper stratosphere during December. The mean-zonal wind anomalies produced in early winter persist by deformation until late winter through wave-mean flow interactions with planetary waves. The modulation effect of the solar influence by the QBO takes place during this process.

Sterilization of bacterial endospores by an atmospheric-pressure argon plasma jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uhm, Han S.; Lim, Jin P.; Li, Shou Z.

2007-06-25

Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. However, the spore-killing efficiency of the atmospheric-pressure argon-oxygen jet depends very sensitively on the oxygen concentration in the argon gas.

North Atlantic winter eddy-driven jet and atmospheric blocking variability in the Community Earth System Model version 1 Large Ensemble simulations

NASA Astrophysics Data System (ADS)

Kwon, Young-Oh; Camacho, Alicia; Martinez, Carlos; Seo, Hyodae

2018-01-01

The atmospheric jet and blocking distributions, especially in the North Atlantic sector, have been challenging features for a climate model to realistically reproduce. This study examines climatological distributions of winter (December-February) daily jet latitude and blocking in the North Atlantic from the 40-member Community Earth System Model version 1 Large Ensemble (CESM1LE) simulations. This analysis aims at examining whether a broad range of internal climate variability encompassed by a large ensemble of simulations results in an improved representation of the jet latitude distributions and blocking days in CESM1LE. In the historical runs (1951-2005), the daily zonal wind at 850 hPa exhibits three distinct preferred latitudes for the eddy-driven jet position as seen in the reanalysis datasets, which represents a significant improvement from the previous version of the same model. However, the meridional separations between the three jet latitudes are much smaller than those in the reanalyses. In particular, the jet rarely migrates to the observed southernmost position around 37°N. This leads to the bias in blocking frequency that is too low over Greenland and too high over the Azores. These features are shown to be remarkably stable across the 40 ensemble members with negligible member-to-member spread. This result implies the range of internal variability of winter jet latitude and blocking frequency within the 55-year segment from each ensemble member is comparable to that represented by the full large ensemble. Comparison with 2046-2100 from the RCP8.5 future projection runs suggests that the daily jet position is projected to maintain the same three preferred latitudes, with a slightly higher frequency of occurrence over the central latitude around 50°N, instead of shifting poleward in the future as documented in some previous studies. In addition, the daily jet speed is projected not to change significantly between 1951-2005 and 2046-2100. On the other hand, the climatological mean jet is projected to become slightly more elongated and stronger on its southern flank, and the blocking frequency over the Azores is projected to decrease.

The Response of a Spectral General Circulation Model to Refinements in Radiative Processes.

NASA Astrophysics Data System (ADS)

Ramanathan, V.; Pitcher, Eric J.; Malone, Robert C.; Blackmon, Maurice L.

1983-03-01

We present here results and analyses of a series of numerical experiments performed with a spectral general circulation model (GCM). The purpose of the GCM experiments is to examine the role of radiation/cloud processes in the general circulation of the troposphere and stratosphere. The experiments were primarily motivated by the significant improvements in the GCM zonal mean simulation as refinements were made in the model treatment of clear-sky radiation and cloud-radiative interactions. The GCM with the improved cloud/radiation model is able to reproduce many observed features, such as: a clear separation between the wintertime tropospheric jet and the polar night jet; winter polar stratospheric temperatures of about 200 K; interhemispheric and seasonal asymmetries in the zonal winds.In a set of sensitivity experiments, we have stripped the cloud/radiation model of its improvements, the result being a significant degradation of the zonal mean simulations by the GCM. Through these experiments we have been able to identify the processes that are responsible for the improved GCM simulations: (i) careful treatment of the upper boundary condition for O3 solar heating; (ii) temperature dependence of longwave cooling by CO2 15 m bands., (iii) vertical distribution of H2O that minimizes the lower stratospheric H2O longwave cooling; (iv) dependence of cirrus emissivity on cloud liquid water content.Comparison of the GCM simulations, with and without the cloud/radiation improvements, reveals the nature and magnitude of the following radiative-dynamical interactions: (i) the temperature decrease (due to errors in radiative heating) within the winter polar stratosphere is much larger than can be accounted for by purely radiative adjustment; (ii) the role of dynamics in maintaining the winter polar stratosphere thermal structure is greatly diminished in the GCM with the degraded treatment of radiation; (iii) the radiative and radiative-dynamical response times of the atmosphere vary from periods of less than two weeks in the lower troposphere to roughly three months in the polar lower stratosphere; (iv) within the stratosphere, the radiative response times vary significantly with temperature, with the winter polar values larger than the summer polar values by as much as a factor of 2.5.Cirrus clouds, if their emissivities are arbitrarily prescribed to be black, unrealistically enhance the radiative cooling of the polar troposphere above 8 km. This results in a meridional temperature gradient much stronger than that which is observed. We employ a more realistic parameterization that accounts for the non-blackness of cirrus, and we describe the resulting improvements in the model simulation of zonal winds, temperatures, and radiation budget.

Mission Control, 1964

NASA Image and Video Library

2016-10-27

This archival image was released as part of a gallery comparing JPL's past and present, commemorating the 80th anniversary of NASA's Jet Propulsion Laboratory on Oct. 31, 2016. When spacecraft in deep space "phone home," they do it through NASA's Deep Space Network. Engineers in this room at NASA's Jet Propulsion Laboratory -- known as Mission Control -- monitor the flow of data. This image was taken in May 1964, when the building this nerve center is in, the Space Flight Operations Facility (Building 230), was dedicated at JPL. http://photojournal.jpl.nasa.gov/catalog/PIA21120

Well development by jetting using coiled tubing and simultaneous pumping.

PubMed

Rosberg, Jan-Erik; Bjelm, Leif

2009-01-01

During flow testing of a deep, 1927-m, gravel packed screen completed well, it became apparent that well development was needed to increase productivity. A hydrojetting system using coiled tubing in combination with simultaneous pumping was developed and tested and found to be successful. To verify whether the jetting improved the well, the results of a pumping test conducted before and after the jetting operation are compared. In addition, flowmeter logging and hydraulic properties obtained from pumping tests conducted during the jetting operation were also used to verify the improvements. Hydrojetting in combination with simultaneous pumping proved to be an effective cleaning method. After 100 min of pumping, around 110 m less drawdown and 15 L/s higher average flow rate were obtained compared to the values before the jetting operation. The skin factor was positive before the jetting operation and negative thereafter, thus providing additional evidence of improvements of the well. The flowmeter data also confirmed the improvements and were valuable in optimizing the jetting operation. It was also found, from the short-term pumping tests conducted during the jetting operation, that the Hantush-Jacob method for leaky confined aquifers is a valuable indicator of the well development. The combination of methods used for the well development in this case can easily be applied on other deep well projects to obtain a controlled and time-efficient well development. Copyright © 2009 The Author(s). Journal Compilation © 2009 National Ground Water Association.

Detection prospects for GeV neutrinos from collisionally heated gamma-ray bursts with IceCube/DeepCore.

PubMed

Bartos, I; Beloborodov, A M; Hurley, K; Márka, S

2013-06-14

Jet reheating via nuclear collisions has recently been proposed as the main mechanism for gamma-ray burst (GRB) emission. In addition to producing the observed gamma rays, collisional heating must generate 10-100 GeV neutrinos, implying a close relation between the neutrino and gamma-ray luminosities. We exploit this theoretical relation to make predictions for possible GRB detections by IceCube + DeepCore. To estimate the expected neutrino signal, we use the largest sample of bursts observed by the Burst and Transient Source Experiment in 1991-2000. GRB neutrinos could have been detected if IceCube + DeepCore operated at that time. Detection of 10-100 GeV neutrinos would have significant implications, shedding light on the composition of GRB jets and their Lorentz factors. This could be an important target in designing future upgrades of the IceCube + DeepCore observatory.

Diagnostic calculations of the circulation in the Martian atmosphere

NASA Technical Reports Server (NTRS)

Santee, Michelle L.; Crisp, David

1995-01-01

The circulation of the Martian atmosphere during late southern summer is derived from atmospheric temperature and dust distributions retrieved from a subset of the Mariner 9 infrared interferometer spectrometer (IRIS) thermal emission spectra (LS = 343-348 deg) (Santee and Crisp, 1933). Zonal-mean zonal winds are calculated by assuming gradient wind balance and zero surface zonal wind. Both hemispheres have intense midlatitude westerly jets with velocities of 80-90 m/s near 50 km; in the southern tropics the winds are easterly with velocities of 40 m/s near 50 km. The net effect of the zonal-mean meridional circulation and large-scale waves can be approximated by the diabatic ciculation, which is defined from the atmospheric thermal structure and net radiative heating rates. The radiative transfer model described by Crisp (1990) and Santee (1993) is used to compute solar heating and thermal cooling rates from diurnal averages of the retrieved IRIS temperature and dust distributions. At pressures below 4 mbar, there are large net radiative heating rates (up to 5 K/d) in the equatorial region and large net radiative cooling rates (up to 12 K/d) in the polar regions. These net radiative heating rates are used in a diagnostic stream function model which solves for the meridonal and vertical components of the diabatic circulation simultaneously. We find a two cell circulation, with rising motion over the equator, poleward flow in both hemispheres, sinking motion over both polar regions, and return flow in the lowest atmospheric levels. The maximum poleward velocity is 3 m/s in the tropics at approximately 55 km altitude, and the maximum vertical velocity is 2.5 cm/s downward over the north pole at approximately 60 km altitude. If these large transport rates are sustained for an entire season, the Martian atmosphere above the 1-mbar level is overturned in about 38 days. This diabatic circulation is qualitatively similar to the terrestial diabatic circulation at the comparable season, but is more vigorous.

Diagnostic calculations of the circulation in the Martian atmosphere

NASA Astrophysics Data System (ADS)

Santee, Michelle L.; Crisp, David

1995-03-01

The circulation of the Martian atmosphere during late southern summer is derived from atmospheric temperature and dust distributions retrieved from a subset of the Mariner 9 infrared interferometer spectrometer (IRIS) thermal emission spectra (LS = 343-348 deg) (Santee and Crisp, 1933). Zonal-mean zonal winds are calculated by assuming gradient wind balance and zero surface zonal wind. Both hemispheres have intense midlatitude westerly jets with velocities of 80-90 m/s near 50 km; in the southern tropics the winds are easterly with velocities of 40 m/s near 50 km. The net effect of the zonal-mean meridional circulation and large-scale waves can be approximated by the diabatic ciculation, which is defined from the atmospheric thermal structure and net radiative heating rates. The radiative transfer model described by Crisp (1990) and Santee (1993) is used to compute solar heating and thermal cooling rates from diurnal averages of the retrieved IRIS temperature and dust distributions. At pressures below 4 mbar, there are large net radiative heating rates (up to 5 K/d) in the equatorial region and large net radiative cooling rates (up to 12 K/d) in the polar regions. These net radiative heating rates are used in a diagnostic stream function model which solves for the meridonal and vertical components of the diabatic circulation simultaneously. We find a two cell circulation, with rising motion over the equator, poleward flow in both hemispheres, sinking motion over both polar regions, and return flow in the lowest atmospheric levels. The maximum poleward velocity is 3 m/s in the tropics at approximately 55 km altitude, and the maximum vertical velocity is 2.5 cm/s downward over the north pole at approximately 60 km altitude. If these large transport rates are sustained for an entire season, the Martian atmosphere above the 1-mbar level is overturned in about 38 days. This diabatic circulation is qualitatively similar to the terrestial diabatic circulation at the comparable season, but is more vigorous.

Diagnostic calculations of the circulation in the Martian atmosphere

NASA Technical Reports Server (NTRS)

Santee, Michelle L.; Crisp, David

1995-01-01

The circulation of the Martian atmosphere during late southern summer is derived from atmospheric temperature and dust distributions retrieved from a subset of the Mariner 9 infrared interferometer spectrometer (IRIS) thermal emission spectra (L(sub s) = 343-348 deg). Zonal-mean zonal winds are calculated by assuming gradient wind balance and zero surface zonal wind. Both hemispheres have intense midlatitude westerly jets with velocities of 80-90 m/s near 50 km; in the southern tropics the winds are easterly with velocities of 40 m/s near 50 km. The net effect of the zonal mean meridional circulation and large-scale waves can be approximated by the diabatic circulation, which is defined from the atmospheric thermal structure and net radiative heating rates. The radiative transfer model described by Crisp (1990) and Santee (1993) is used to compute solar heating and thermal cooling rates from diurnal averages of the retrieved IRIS temperature and dust distributions. At pressures below 4 mbar, there are large net radiative heating rates (up to 5 K/d) in the equatorial region and large net radiative cooling rates (up to 12 K/d) in the polar regions. These net radiative heating rates are used in a diagnostic stream function model which solves for the meridional and vertical components of the diabatic circulation simultaneously. We find a two-cell circulation, with rising motion over the equator, poleward flow in both hemispheres, sinking motion over both polar regions, and return flow in the lowest atmospheric levels. The maximum poleward velocity is 3 m/s in the tropics at approx. 55 km altitude, and the maximum vertical velocity is 2.5 cm/s downward over the north pole at approx. 60 km altitude. If these large transport rates are sustained for an entire season, the Martian atmosphere above the 1-mbar level is overturned in about 38 days. This diabatic circulation is qualitatively similar to the terrestrial diabatic circulation at the comparable season, but is more vigorous.

The stratospheric quasi-biennial oscillation in the NCEP reanalyses: Climatological structures

NASA Astrophysics Data System (ADS)

Huesmann, Amihan S.; Hitchman, Matthew H.

2001-06-01

Global quasi-biennial variation in the lower stratosphere and tropopause region is studied using 41 years (1958-1998) of reanalyses from the National Centers for Environmental Prediction (NCEP). Horizontal wind, temperature, geopotential height, tropopause temperature and pressure fields are used. A new quasi-biennial oscillation (QBO) indexing method is presented, which is based on the zonal mean zonal wind shear anomaly at the equator and is compared to the Singapore index. A phase difference composting technique provides ``snapshots'' of the QBO meridional-vertical structure as it descends, and ``composite phases'' provide a look at its time progression. Via binning large amounts of data, the first observation-based estimate of the QBO meridional circulation is obtained. High-latitude QBO variability supports previous studies that invoke planetary wave-mean flow interaction as an explanation. The meridional distribution of the range in QBO zonal wind is compared with the stratospheric annual cycle, with the annual cycle dominating poleward of ~12° latitude but still being significant in the deep tropics. The issues of temporal shear zone asymmetries and phase locking with the annual cycle are critically examined. Subtracting the time mean and annual cycle removes ~2/3 of the asymmetry in wind (and wind shear) zone descent rate. The NCEP data validate previous findings that both the easterly and westerly QBO anomalous wind regimes in the lower stratosphere change sign preferentially during northern summer. It is noteworthy that the NCEP QBO amplitude and the relationships among the reanalysed zonal wind, temperature, and meridional circulation undergo a substantial change around 1978.

Observations of comet 19P/Borrelly by the miniature integrated camera and spectrometer aboard deep space 1

USGS Publications Warehouse

Soderblom, L.A.; Becker, T.L.; Bennett, G.; Boice, D.C.; Britt, D.T.; Brown, R.H.; Buratti, B.J.; Isbell, C.; Giese, B.; Hare, T.; Hicks, M.D.; Howington-Kraus, E.; Kirk, R.L.; Lee, M.; Nelson, R.M.; Oberst, J.; Owen, T.C.; Rayman, M.D.; Sandel, B.R.; Stern, S.A.; Thomas, N.; Yelle, R.V.

2002-01-01

The nucleus of the Jupiter-family comet 19P/Borrelly was closely observed by the Miniature Integrated Camera and Spectrometer aboard the Deep Space 1 spacecraft on 22 September 2001. The 8-kilometer-long body is highly variegated on a scale of 200 meters, exhibiting large albedo variations (0.01 to 0.03) and complex geologic relationships. Short-wavelength infrared spectra (1.3 to 2.6 micrometers) show a slope toward the red and a hot, dry surface (???345 kelvin, with no trace of water ice or hydrated minerals), consistent with ???10% or less of the surface actively sublimating. Borrelly's coma exhibits two types of dust features: fans and highly collimated jets. At encounter, the near-nucleus coma was dominated by a prominent dust jet that resolved into at least three smaller jets emanating from a broad basin in the middle of the nucleus. Because the major dust jet remained fixed in orientation, it is evidently aligned near the rotation axis of the nucleus.

Cassini ISS Observation of Saturn from Grand Finale Orbits

NASA Astrophysics Data System (ADS)

Blalock, J. J.; Sayanagi, K. M.; Ingersoll, A. P.; Dyudina, U.; Ewald, S. P.; McCabe, R. M.; Garland, J.; Gunnarson, J.; Gallego, A.

2017-12-01

We present images captured during Cassini's Grand Finale orbits, and their preliminary analyses. During the final 22 orbits of the mission, the spacecraft is in orbits that have 6.5 day period at an inclination of 62 degrees, apoapsis altitude of about 1,272,000 km, and periapsis altitudes of about 2,500 km. Images captured during periapsis passes show Saturn's atmosphere at unprecedented spatial resolution. We present preliminary analyses of these images, including the final images captured before the end of the mission when the spacecraft enters Saturn's atmosphere on September 15th, 2017. Prominent features captured during the final orbits include the north polar vortex and other vortices as well as very detailed views of the "popcorn clouds" that reside between the Hexagon and the north pole. In the cloud field between zonal jets, clouds either resemble linear streaks suggestive of cirrus-like clouds or round shapes suggestive of vortices or cumulus anvil. The presence of linear streaks that follow lines of constant latitudes suggests that meridional mixing is inhibited at those latitudes. The size of vortices may reflect latitudinal variation in the atmospheric deformation radius. We also compare the new images to those captured earlier in the Cassini mission to characterize the temporal evolution such as changes in the zonal jet speeds, and prevalence and colors of vortices. A particular focus of our interest is the long-term change in the color of the hexagon, the evolution of the wind speeds in the jetstream that blows eastward at the boundary of the hexagon, and the morphology of the north polar vortex. Our work has been supported by NASA PATM NNX14AK07G, NSF AAG 1212216, and NASA NESSF NNX15AQ70H.

Atmospheric circulation of extrasolar giant planets

NASA Astrophysics Data System (ADS)

Showman, A. P.

2012-12-01

Of the many known extrasolar planets, over 100 have orbital semi-major axes less than 0.1 AU, and a significant fraction of these hot Jupiters and Neptunes are known to transit their stars, allowing them to be characterized with the Spitzer, Hubble, and groundbased telescopes. The stellar flux incident on these planets is expected to drive an atmospheric circulation that shapes the day-night temperature difference, infrared light curves, spectra, albedo, and atmospheric composition, and recent Spitzer infrared light curves show evidence for dynamical meteorology in these planets' atmospheres. Here, I will survey basic dynamical ideas and detailed 3D numerical models that illuminate the atmospheric circulation of these exotic, tidally locked planets. These models suggest that, generally, the circulation will be characterized by broad, fast zonal jets, with day-night temperature contrasts at the photosphere that may vary from small in some cases to large in others. I will discuss the dynamical mechanisms for maintaining the fast zonal jets that develop in these models, as well as the mechanisms for controlling the temperature patterns, including the day-night temperature contrasts. These mechanisms help to explain current observations, and they predict regime transitions for how the wind and temperature patterns should vary with the incident stellar flux, strength of atmospheric drag, and other parameters. These transitions are observable and in some cases are already becoming evident in the data. I will also compare the circulation of the hot Jupiters to that of young, massive giant planets being directly imaged around other stars, which will be the subject of a new observational vanguard over the next decade. To emphasize the similarities as well as differences, I will ground this discussion in our understanding of the more familiar atmospheric dynamical regime of Earth, as well as our "local" giant planets Jupiter, Saturn, Uranus, and Neptune.

Atmospheric circulation of extrasolar giant planets

NASA Astrophysics Data System (ADS)

Showman, A. P.

2011-12-01

Of the many known extrasolar planets, nearly 200 have orbital semi-major axes less than 0.1 AU, and a significant fraction of these hot Jupiters and Neptunes are known to transit their stars, allowing them to be characterized with the Spitzer, Hubble, and groundbased telescopes. The stellar flux incident on these planets is expected to drive an atmospheric circulation that shapes the day-night temperature difference, infrared light curves, spectra, albedo, and atmospheric composition, and recent Spitzer infrared light curves show evidence for dynamical meteorology in these planets' atmospheres. Here, I will survey basic dynamical ideas and detailed 3D numerical models that illuminate the atmospheric circulation of these exotic, tidally locked planets. These models suggest that, generally, the circulation will be characterized by broad, fast zonal jets, with day-night temperature contrasts at the photosphere that may vary from small in some cases to large in others. I will discuss the dynamical mechanisms for maintaining the fast zonal jets that develop in these models, as well as the mechanisms for controlling the temperature patterns, including the day-night temperature contrasts. These mechanisms help to explain current observations, and they predict regime transitions for how the wind and temperature patterns should vary with the incident stellar flux, strength of atmospheric drag, and other parameters. These transitions are observable and in some cases are already becoming evident in the data. I will also compare the circulation of the hot Jupiters to that of young, massive giant planets being directly imaged around other stars, which will be the subject of a new observational vanguard over the next decade. To emphasize the similarities as well as differences, I will ground this discussion in our understanding of the more familiar atmospheric dynamical regime of Earth, as well as our "local" giant planets Jupiter, Saturn, Uranus, and Neptune.

Droplet impact on deep liquid pools: Rayleigh jet to formation of secondary droplets

NASA Astrophysics Data System (ADS)

Castillo-Orozco, Eduardo; Davanlou, Ashkan; Choudhury, Pretam K.; Kumar, Ranganathan

2015-11-01

The impact of droplets on a deep pool has applications in cleaning up oil spills, spray cooling, painting, inkjet printing, and forensic analysis, relying on the changes in properties such as viscosity, interfacial tension, and density. Despite the exhaustive research on different aspects of droplet impact, it is not clear how liquid properties can affect the instabilities leading to Rayleigh jet breakup and number of daughter drops formed after its pinch-off. In this article, through systematic experiments we investigate the droplet impact phenomena by varying viscosity and surface tension of liquids as well as impact speeds. Further, using numerical simulations, we show that Rayleigh-Plateau instability is influenced by these parameters, and capillary time scale is the appropriate scale to normalize the breakup time. Based on Ohnesorge number (Oh) and impact Weber number (We), a regime map for no breakup, Rayleigh jet breakup, and crown splash is suggested. Interestingly, crown splash is observed to occur at all Ohnesorge numbers; however, at high Oh, a large portion of kinetic energy is dissipated, and thus the Rayleigh jet is suppressed regardless of high impact velocity. The normalized required time for the Rayleigh jet to reach its peak varies linearly with the critical height of the jet.

Three-dimensional structures of equatorial waves and the resulting super-rotation in the atmosphere of a tidally locked hot Jupiter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, Shang-Min; Gu, Pin-Gao; Dobbs-Dixon, Ian

Three-dimensional (3D) equatorial trapped waves excited by stellar isolation and the resulting equatorial super-rotating jet in a vertical stratified atmosphere of a tidally locked hot Jupiter are investigated. Taking the hot Jupiter HD 189733b as a fiducial example, we analytically solve linear equations subject to stationary stellar heating with a uniform zonal-mean flow included. We also extract wave information in the final equilibrium state of the atmosphere from our radiative hydrodynamical simulation for HD 189733b. Our analytic wave solutions are able to qualitatively explain the 3D simulation results. Apart from previous wave studies, investigating the vertical structure of waves allowsmore » us to explore new wave features such as the wavefronts tilts related to the Rossby-wave resonance as well as dispersive equatorial waves. We also attempt to apply our linear wave analysis to explain some numerical features associated with the equatorial jet development seen in the general circulation model by Showman and Polvani. During the spin-up phase of the equatorial jet, the acceleration of the jet can be in principle boosted by the Rossby-wave resonance. However, we also find that as the jet speed increases, the Rossby-wave structure shifts eastward, while the Kelvin-wave structure remains approximately stationary, leading to the decline of the acceleration rate. Our analytic model of jet evolution implies that there exists only one stable equilibrium state of the atmosphere, possibly implying that the final state of the atmosphere is independent of initial conditions in the linear regime. Limitations of our linear model and future improvements are also discussed.« less

Wintertime East Asian Jet Stream and Its Association with the Asian-Pacific Climate

NASA Technical Reports Server (NTRS)

Yang, Song; Lau, K.-M.; Kim, K.-M.

2000-01-01

Interannual variability of the wintertime East Asian westerly jet stream and the linkage between this variability and the Asian-Pacific climate are investigated. The study emphasizes on the variability of the jet core and its association with the Asian winter monsoon, tropical convection, upper tropospheric wave patterns, and the teleconnection of the jet with other climate systems. The relationship between the jet and North Pacific sea surface temperature pattern (SST) is also explored. NCEP/NCAR reanalysis, NASA GISS surface temperature, NASA GEOS reanalysis, NOAA reconstructed SST, GPCP precipitation, and NOAA snow cover data sets are analyzed in this study. An index of the East Asian jet has been defined by the December-February means of the 200 mb zonal winds that are averaged within a box enclosing the jet maximum, which shifts only moderately from one year to another especially in the south-north direction. The jet links to a teleconnection pattern whose major climate anomalies appear over the Asian continent and western Pacific (west of the dateline). This pattern differs distinctly from the teleconnection pattern associated with El Nino/Southern Oscillation (ENSO), which causes the Pacific/North American pattern to the east of the dateline. A strong jet is accompanied clearly by an increase in the intensity of the atmospheric circulation over Asia and the Pacific. In particular, the winter monsoon strengthens over East Asia, leading to cold climate in the region, and convection intensifies over the tropical Asia-Australia sector. Changes in the jet are associated with broad-scale modification in the upper tropospheric wave patterns that leads to downstream climate anomalies over the eastern Pacific. Through this downstream influence, the East Asian jet causes climate signals in North America as well. A strong jet gives rise to warming and less snow cover in the western United States but reverse climate anomalies in the eastern part of the country, although these signals are relatively weaker than the jet-related anomalies in East Asia. There is a strong association between the East Asian jet and the North Pacific SST (NPSST). A strong jet is accompanied by a cooling in the extratropical Pacific and a warming in the tropical-subtropical Pacific. Evidence also indicates that the extratropical NPSST pattern plays a role in modulating the intensity of the jet stream. ENSO, the jet, and the NPSST are mutually interactive on certain time scales and such an interaction links closely to the climate anomalies in the Asian-Pacific-American regions.

Sources and distribution of NO(x) in the upper troposphere at northern midlatitudes

NASA Technical Reports Server (NTRS)

Rohrer, Franz; Ehhalt, Dieter H.; Wahner, Andreas

1994-01-01

A simple quasi 2-D model is used to study the zonal distribution of NO(x). The model includes vertical transport in form of eddy diffusion and deep convection, zonal transport by a vertically uniform wind, and a simplified chemistry of NO, NO2 and HNO3. The NO(x) sources considered are surface emissions (mostly from the combustion of fossil fuel), lightning, aircraft emissions, and downward transport from the stratosphere. The model is applied to the latitude band of 40 deg N to 50 deg N during the month of June; the contributions to the zonal NO(x) distribution from the individual sources and transport processes are investigated. The model predicted NO(x) concentration in the upper troposphere is dominated by air lofted from the polluted planetary boundary layer over the large industrial areas of Eastern North America and Europe. Aircraft emissions are also important and contribute on average 30 percent. Stratospheric input is minor about 10 percent, less even than that by lightning. The model provides a clear indication of intercontinental transport of NO(x) and HNO3 in the upper troposphere. Comparison of the modelled NO profiles over the Western Atlantic with those measured during STRATOZ 3 in 1984 shows good agreement at all altitudes.

Zonal asymmetric evolution of aerosol optical depth in the subtropics of northern hemisphere in boreal spring and its association with the thermal forcing of Tibetan Plateau

NASA Astrophysics Data System (ADS)

Liu, B.; Jin, Q.; He, J.

2017-12-01

More than 70% population living in the subtropics of the northern hemisphere are exposed to the serious air pollution. In the present, the zonal asymmetric evolution of the 550-nm aerosol optical depth (AOD) over this region has been observed between the East Asian (EA) and the East North American (ENA) continent from boreal winter to summer. The peak of AOD emerges in April over the EA and decreases evidently till June, meanwhile the AOD is still increasing over the ENA, although the low-level southerly is prevailing over the two areas. The diagnosis suggests that such zonal asymmetry is ascribed to the distinct feedback between general circulation and atmospheric heat source (AHS) in situ. The condensation heating becomes dominant in the AHS over the East Asia in April, along with the low-level southerly and the upper-tropospheric northerly, implicating the formation of summertime circulation pattern. Afterwards, the deep convection and the ventilation with strong ascending is generated to reduce the AOD over the EA. Whereas the similar configuration between circulation and AHS takes place over the ENA in June. Furthermore, the possible reason for the different evolution of atmospheric heating source between East Asia and East North America has been discussed.

The effect of Jupiter oscillations on Juno gravity measurements

NASA Astrophysics Data System (ADS)

Durante, Daniele; Guillot, Tristan; Iess, Luciano

2017-01-01

Seismology represents a unique method to probe the interiors of giant planets. Recently, Saturn's f-modes have been indirectly observed in its rings, and there is strong evidence for the detection of Jupiter global modes by means of ground-based, spatially-resolved, velocimetry measurements. We propose to exploit Juno's extremely accurate radio science data by looking at the gravity perturbations that Jupiter's acoustic modes would produce. We evaluate the perturbation to Jupiter's gravitational field using the oscillation spectrum of a polytrope with index 1 and the corresponding radial eigenfunctions. We show that Juno will be most sensitive to the fundamental mode (n = 0), unless its amplitude is smaller than 0.5 cm/s, i.e. 100 times weaker than the n ∼ 4 - 11 modes detected by spatially-resolved velocimetry. The oscillations yield contributions to Juno's measured gravitational coefficients similar to or larger than those expected from shallow zonal winds (extending to depths less than 300 km). In the case of a strong f-mode (radial velocity ∼ 30 cm/s), these contributions would become of the same order as those expected from deep zonal winds (extending to 3000 km), especially on the low degree zonal harmonics, therefore requiring a new approach to the analysis of Juno data.

Winds Near Jupiter's Belt-Zone Boundary

NASA Technical Reports Server (NTRS)

1997-01-01

Time Sequence of a belt-zone boundary near Jupiter's equator. These mosaics show Jupiter's appearance at 757 nanometers (near-infrared) and were taken nine hours apart. Images at 757 nanometers show features of Jupiter's primary visible cloud deck.

Jupiter's atmospheric circulation is dominated by alternating jets of east/west (zonal) winds. The bands have different widths and wind speeds but have remained constant as long as telescopes and spacecraft have measured them. A strong eastward jet is made visible as it stretches the clouds just below the center of this mosaic. The maximum wind speed of this jet is 128 meters per second (286 miles per hour). Features on this jet move about one quarter of the width of the mosaic. All the features visible in these mosaics are moving eastward (right).

North is at the top. The mosaic covers latitudes -13 to +3 degrees and is centered at longitude 282 degrees West. The smallest resolved features are tens of kilometers in size. These images were taken on November 5th, 1996, at a range of 1.2 million kilometers by the Solid State Imaging system aboard NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

Origin of the 2016 QBO Disruption and Its Relationship to Extreme El Niño Events

NASA Astrophysics Data System (ADS)

Barton, C. A.; McCormack, J. P.

2017-11-01

The descent of the westerly phase of the quasi-biennial oscillation (QBO) in equatorial stratospheric zonal wind was interrupted by the development of easterlies near 40 hPa ( 23 km altitude) in early 2016. We use tropical meteorological analyses of wind and temperature to describe in detail the special circumstances by which equatorward-propagating planetary waves produced this unprecedented disruption in the QBO. Our findings show that the subtropical easterly jet in the winter lower stratosphere during the 2015-2016 winter was anomalously weak owing to (1) the timing of the QBO relative to the annual cycle and (2) an extreme El Niño event. The weak jet allowed an unusually large flux of westward momentum to propagate from the extratropical Northern Hemisphere to the equator near the 40 hPa level. Consequently, the QBO westerlies at that level experienced sustained easterly acceleration from extratropical wave breaking, leading to the observed wind reversal.

A Celestial Reference Frame at X/ka-Band (8.4/32 Ghz) for Deep Space Navigation

NASA Technical Reports Server (NTRS)

Jacobs, C. S.; Clark, J. E.; Garcia-Miro, C.; Horiuchi, S.; Romero-Wolf, A.; Snedeker, L.; Sotuela, I.

2012-01-01

Deep space tracking and navigation are done in a quasi-inertial reference frame based upon the angular positions of distant active galactic nuclei (AGN). These objects, which are found at extreme distances characterized by median redshifts of z = 1, are ideal for reference frame definition because they exhibit no measurable parallax or proper motion. They are thought to be powered by super massive black holes whose gravitational energy drives galactic sized relativistic jets. These jets produce synchrotron emissions which are detectable by modern radio techniques such as Very Long baseline Interferometry (VLBI).

Field testing of jet-grouted piles and drilled shafts.

DOT National Transportation Integrated Search

2014-01-01

A field study of deep foundations supporting high mast lighting and signage was undertaken in typical Florida : soils. Three drilled shafts (48 in x12 ft and two 48 in x18 ft) and two jet-grouted piles (28 in x18 ft) were : constructed in Keystone He...

Demarcating Circulation Regimes of Synchronously Rotating Terrestrial Planets within the Habitable Zone

NASA Astrophysics Data System (ADS)

Haqq-Misra, Jacob; Wolf, Eric. T.; Joshi, Manoj; Zhang, Xi; Kopparapu, Ravi Kumar

2018-01-01

We investigate the atmospheric dynamics of terrestrial planets in synchronous rotation within the habitable zone of low-mass stars using the Community Atmosphere Model. The surface temperature contrast between the day and night hemispheres decreases with an increase in incident stellar flux, which is opposite the trend seen in gas giants. We define three dynamical regimes in terms of the equatorial Rossby deformation radius and the Rhines length. The slow rotation regime has a mean zonal circulation that spans from the day to the night sides, which occurs for planets around stars with effective temperatures of 3300–4500 K (rotation period > 20 days), with both the Rossby deformation radius and the Rhines length exceeding the planetary radius. Rapid rotators have a mean zonal circulation that partially spans a hemisphere and with banded cloud formation beneath the substellar point, which occurs for planets orbiting stars with effective temperatures of less than 3000 K (rotation period < 5 days), with the Rossby deformation radius less than the planetary radius. In between is the Rhines rotation regime, which retains a thermally direct circulation from the day side to the night side but also features midlatitude turbulence-driven zonal jets. Rhines rotators occur for planets around stars in the range of 3000–3300 K (rotation period ∼5–20 days), where the Rhines length is greater than the planetary radius but the Rossby deformation radius is less than the planetary radius. The dynamical state can be observationally inferred from a comparison of the morphologies of the thermal emission phase curves of synchronously rotating planets.

A planetary-scale disturbance in a long living three vortex coupled system in Saturn's atmosphere

NASA Astrophysics Data System (ADS)

del Río-Gaztelurrutia, T.; Sánchez-Lavega, A.; Antuñano, A.; Legarreta, J.; García-Melendo, E.; Sayanagi, K. M.; Hueso, R.; Wong, M. H.; Pérez-Hoyos, S.; Rojas, J. F.; Simon, A. A.; de Pater, I.; Blalock, J.; Barry, T.

2018-03-01

The zonal wind profile of Saturn has a unique structure at 60°N with a double-peaked jet that reaches maximum zonal velocities close to 100 ms-1. In this region, a singular group of vortices consisting of a cyclone surrounded by two anticyclones was active since 2012 until the time of this report. Our observation demonstrates that vortices in Saturn can be long-lived. The three-vortex system drifts at u = 69.0 ± 1.6 ms-1, similar to the speed of the local wind. Local motions reveal that the relative vorticity of the vortices comprising the system is ∼2-3 times the ambient zonal vorticity. In May 2015, a disturbance developed at the location of the triple vortex system, and expanded eastwards covering in two months a third of the latitudinal circle, but leaving the vortices essentially unchanged. At the time of the onset of the disturbance, a fourth vortex was present at 55°N, south of the three vortices and the evolution of the disturbance proved to be linked to the motion of this vortex. Measurements of local motions of the disturbed region show that cloud features moved essentially at the local wind speeds, suggesting that the disturbance consisted of passively advecting clouds generated by the interaction of the triple vortex system with the fourth vortex to the south. Nonlinear simulations are able to reproduce the stability and longevity of the triple vortex system under low vertical wind shear and high static stability in the upper troposphere of Saturn.

Is there a quasi-biennial oscillation in tropical deep convection?

NASA Astrophysics Data System (ADS)

Collimore, Christopher C.; Hitchman, Matthew H.; Martin, David W.

We investigate the possibility that the stratospheric Quasi-Biennial Oscillation (QBO) modulates deep convection in the tropics. Interannual variations of outgoing longwave radiation (OLR) in the tropics during 1975-87 are compared with stratospheric zonal winds at Singapore (a measure of the QBO), and with the Tahiti-Darwin sea level pressure difference (the Southern Oscillation Index, or SOI). A monthly time series of anomalous OLR was constructed for regions of consistently low OLR, thus targeting areas of chronic deep convection. This “chronic cold” index and the SOI correlate at -0.6 for zero lag. The “chronic cold” index correlates with 30 hPa Singapore winds at +0.3 and with 50 hPa-70 hPa wind differences at +0.4, both near zero lag. These results are not inconsistent with the hypothesis that deep convection may be enhanced in chronically cold areas when QBO westward shear exists in the lower stratosphere, and diminished during eastward shear.

Jupiter Eruptions Captured in Infrared

NASA Technical Reports Server (NTRS)

2008-01-01

[figure removed for brevity, see original site] Click on the image for high resolution image of Nature Cover

Detailed analysis of two continent-sized storms that erupted in Jupiter's atmosphere in March 2007 shows that Jupiter's internal heat plays a significant role in generating atmospheric disturbances. Understanding these outbreaks could be the key to unlock the mysteries buried in the deep Jovian atmosphere, say astronomers.

This infrared image shows two bright plume eruptions obtained by the NASA Infrared Telescope Facility on April 5, 2007.

Understanding these phenomena is important for Earth's meteorology where storms are present everywhere and jet streams dominate the atmospheric circulation. Jupiter is a natural laboratory where atmospheric scientists study the nature and interplay of the intense jets and severe atmospheric phenomena.

According to the analysis, the bright plumes were storm systems triggered in Jupiter's deep water clouds that moved upward in the atmosphere vigorously and injected a fresh mixture of ammonia ice and water about 20 miles (30 kilometers) above the visible clouds. The storms moved in the peak of a jet stream in Jupiter's atmosphere at 375 miles per hour (600 kilometers per hour). Models of the disturbance indicate that the jet stream extends deep in the buried atmosphere of Jupiter, more than 60 miles (approximately100 kilometers) below the cloud tops where most sunlight is absorbed.

Jupiter Eruptions

NASA Technical Reports Server (NTRS)

2008-01-01

[figure removed for brevity, see original site] Click on the image for high resolution image of Nature Cover

Detailed analysis of two continent-sized storms that erupted in Jupiter's atmosphere in March 2007 shows that Jupiter's internal heat plays a significant role in generating atmospheric disturbances. Understanding these outbreaks could be the key to unlock the mysteries buried in the deep Jovian atmosphere, say astronomers.

This visible-light image is from NASA's Hubble Space Telescope taken on May 11, 2007. It shows the turbulent pattern generated by the two plumes on the upper left part of Jupiter.

Understanding these phenomena is important for Earth's meteorology where storms are present everywhere and jet streams dominate the atmospheric circulation. Jupiter is a natural laboratory where atmospheric scientists study the nature and interplay of the intense jets and severe atmospheric phenomena.

According to the analysis, the bright plumes were storm systems triggered in Jupiter's deep water clouds that moved upward in the atmosphere vi gorously and injected a fresh mixture of ammonia ice and water about 20 miles (30 kilometers) above the visible clouds. The storms moved in the peak of a jet stream in Jupiter's atmosphere at 375 miles per hour (600 kilometers per hour). Models of the disturbance indicate that the jet stream extends deep in the buried atmosphere of Jupiter, more than 60 miles (approximately100 kilometers) below the cloud tops where most sunlight is absorbed.

New Chandra observations of the jet in 3C273. 1. Softer X-ray than radio spectra and the X-ray emission mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jester, Sebastian; /Fermilab; Harris, D.E.

2006-05-01

The jet in 3C273 is a high-power quasar jet with radio, optical and X-ray emission whose size and brightness allow a detailed study of the emission processes acting in it. We present deep Chandra observations of this jet and analyze the spectral properties of the jet emission from radio through X-rays. We find that the X-ray spectra are significantly softer than the radio spectra in all regions of the bright part of the jet except for the first bright ''knot A'', ruling out a model in which the X-ray emission from the entire jet arises from beamed inverse-Compton scattering ofmore » cosmic microwave background photons in a single-zone jet flow. Within two-zone jet models, we find that a synchrotron origin for the jet's X-rays requires fewer additional assumptions than an inverse-Compton model, especially if velocity shear leads to efficient particle acceleration in jet flows.« less

The Spectacular Radio-Near-IR-X-Ray Jet of 3C 111: the X-Ray Emission Mechanism and Jet Kinematics

NASA Technical Reports Server (NTRS)

Clautice, Devon; Perlman, Eric S.; Georganopoulos, Markos; Lister, Matthew L.; Tombesi, Francesco; Cara, Mihai; Marshall, Herman L.; Hogan, Brandon M.; Kazanas, Demos

2016-01-01

Relativistic jets are the most energetic manifestation of the active galactic nucleus (AGN) phenomenon. AGN jets are observed from the radio through gamma-rays and carry copious amounts of matter and energy from the subparsec central regions out to the kiloparsec and often megaparsec scale galaxy and cluster environs. While most spatially resolved jets are seen in the radio, an increasing number have been discovered to emit in the optical/near- IR and/or X-ray bands. Here we discuss a spectacular example of this class, the 3C 111 jet, housed in one of the nearest, double-lobed FR II radio galaxies known. We discuss new, deep Chandra and Hubble Space Telescope (HST) observations that reveal both near-IR and X-ray emission from several components of the 3C 111 jet, as well as both the northern and southern hotspots. Important differences are seen between the morphologies in the radio, X-ray, and near-IR bands. The long (over 100 kpc on each side), straight nature of this jet makes it an excellent prototype for future, deep observations, as it is one of the longest such features seen in the radio, near-IR/optical, and X-ray bands. Several independent lines of evidence, including the X-ray and broadband spectral shape as well as the implied velocity of the approaching hotspot, lead us to strongly disfavor the EC/CMB model and instead favor a two-component synchrotron model to explain the observed X-ray emission for several jet components. Future observations with NuSTAR, HST, and Chandra will allow us to further constrain the emission mechanisms.

THE SPECTACULAR RADIO-NEAR-IR-X-RAY JET OF 3C 111: THE X-RAY EMISSION MECHANISM AND JET KINEMATICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clautice, Devon; Perlman, Eric S.; Georganopoulos, Markos

2016-08-01

Relativistic jets are the most energetic manifestation of the active galactic nucleus (AGN) phenomenon. AGN jets are observed from the radio through gamma-rays and carry copious amounts of matter and energy from the sub-parsec central regions out to the kiloparsec and often megaparsec scale galaxy and cluster environs. While most spatially resolved jets are seen in the radio, an increasing number have been discovered to emit in the optical/near-IR and/or X-ray bands. Here we discuss a spectacular example of this class, the 3C 111 jet, housed in one of the nearest, double-lobed FR II radio galaxies known. We discuss new,more » deep Chandra and Hubble Space Telescope ( HST ) observations that reveal both near-IR and X-ray emission from several components of the 3C 111 jet, as well as both the northern and southern hotspots. Important differences are seen between the morphologies in the radio, X-ray, and near-IR bands. The long (over 100 kpc on each side), straight nature of this jet makes it an excellent prototype for future, deep observations, as it is one of the longest such features seen in the radio, near-IR/optical, and X-ray bands. Several independent lines of evidence, including the X-ray and broadband spectral shape as well as the implied velocity of the approaching hotspot, lead us to strongly disfavor the EC/CMB model and instead favor a two-component synchrotron model to explain the observed X-ray emission for several jet components. Future observations with NuSTAR , HST , and Chandra will allow us to further constrain the emission mechanisms.« less

Deep Space Network Antenna Monitoring Using Adaptive Time Series Methods and Hidden Markov Models

NASA Technical Reports Server (NTRS)

Smyth, Padhraic; Mellstrom, Jeff

1993-01-01

The Deep Space Network (DSN)(designed and operated by the Jet Propulsion Laboratory for the National Aeronautics and Space Administration (NASA) provides end-to-end telecommunication capabilities between earth and various interplanetary spacecraft throughout the solar system.

The effect of breaking gravity waves on the dynamics and chemistry of the mesosphere and lower thermosphere (invited review)

NASA Technical Reports Server (NTRS)

Garcia, R. R.

1986-01-01

The influence of breaking gravity waves on the dynamics and chemical composition of the 60 to 110 km region is investigated with a two dimensional model that includes a parameterization of gravity wave momentum deposition and diffusion. The dynamical model is described by Garcia and Solomon (1983) and Solomon and Garcia (1983) and includes a complete chemical scheme for the mesosphere and lower thermosphere. The parameterization of Lindzen (1981) is used to calculate the momentum deposited and the turbulent diffusion produced by the gravity waves. It is found that wave momentum deposition drives a very vigorous mean meridional circulation, produces a very cold summer mesopause and reverse the zonal wind jets above about 85 km. The seasonal variation of the turbulent diffusion coefficient is consistent with the behavior of mesospheric turbulences inferred from MST radar echoes. The large degree of consistency between model results and various types of dynamical and chemical data supports very strongly the hypothesis that breaking gravity waves play a major role in determining the zonally-averaged dynamical and chemical structure of the 60 to 110 km region of the atmosphere.

Global Empirical Model of the TEC Response to Geomagnetic Activity and Forcing from Below

DTIC Science & Technology

2014-04-01

solar minimum conditions. Much of the attendant variability is attributable to upward-propagating solar tides excited by latent heating due to deep...Mukhtarov et al. (2010a) found strong evidence indicating that the auroral heating is a main origin of the lower thermospheric SPW1 structure. The...weaker than that of D0 (not shown here). All zonally symmetric tidal components show amplifications like stripes between -40o and -70o modip

Characteristics and mechanism of deep mesoscale variability south of the Kuroshio Extension

NASA Astrophysics Data System (ADS)

Miyamoto, Masatoshi; Oka, Eitarou; Yanagimoto, Daigo; Fujio, Shinzou; Mizuta, Genta; Imawaki, Shiro; Kurogi, Masao; Hasumi, Hiroyasu

2017-05-01

To clarify the characteristics and mechanism of mesoscale variability in the deep ocean, we analyzed historical mooring observations conducted at Site R (30°N, 147°E) south of the Kuroshio Extension during 1978-85 and the 10-year output of an eddy-resolving ocean general circulation model. The power spectral density (PSD) of current velocity at a depth of 5000 m had a peak at periods of 45-75 days at two mooring stations that were zonally 98 km apart and at 54 days at Site R in the model. In the model, the PSD at 54 days at 5000 m had a horizontal maximum 100 km north of Site R as well as in the Kuroshio Extension region 500 km north of Site R. Within the high-PSD region near Site R, variability in the velocity was coherent, and its phase propagation was characterized by zonal and meridional wavenumbers of -2.9×10-5 and 0.1×10-5 rad m-1, respectively, the former of which was comparable to the value of -2.6×10-5 rad m-1 obtained from the mooring observations. Such wavenumbers matched well with the dispersion relation of barotropic topographic Rossby waves (TRWs). Backward ray tracing and PSD distribution suggested that the barotropic TRWs at Site R were generated in the Kuroshio Extension region, and their energy propagated southward.

The deep meridional overturning circulation in the Indian Ocean inferred from the GECCO synthesis

NASA Astrophysics Data System (ADS)

Wang, Weiqiang; Köhl, Armin; Stammer, Detlef

2012-11-01

The deep time-varying meridional overturning circulation (MOC) in the Indian Ocean in the German “Estimating the Circulation and Climate of the Ocean” consortium efforts (GECCO) ocean synthesis is being investigated. An analysis of the integrated circulation suggests that, on time average, 2.1 Sv enter the Indian Ocean in the bottom layer (>3200 m) from the south and that 12.3 Sv leave the Indian Ocean in the upper and intermediate layers (<1500 m), composed of the up-welled bottom layer inflow water, augmented by 9.6 Sv Indonesian Throughflow (ITF) water. The GECCO time-mean results differ substantially from those obtained by inverse box models, which being based on individual hydrographic sections and due to the strong seasonal cycle are susceptible to aliasing. The GECCO solution shows a large seasonal variation in its deep MOC caused by the seasonal reversal of monsoon-related wind stress forcing. The associated seasonal variations of the deep MOC range from -7 Sv in boreal winter to 3 Sv in summer. In addition, the upper and bottom transports across the 34°S section show pronounced interannual variability with roughly biennial variations superimposed by strong anomalies during each La Niña phase as well as the ITF, which mainly affect the upper layer transports. On decadal and longer timescale, the meridional overturning variability as well as long-term trends differs before and after 1980. GECCO shows a stable trend for the period 1960-1979 and substantial changes in the upper and bottom layer for the period 1980-2001. By means of an extended EOF analysis, the importance of Ekman dynamics as driving forces of the deep MOC of the Indian Ocean on the interannual timescale is highlighted. The leading modes of the zonal and meridional wind stress favour a basin-wide meridional overturning mode via Ekman upwelling or downwelling mostly in the central and eastern Indian Ocean. Moreover, tropical zonal wind stress along the equator and alongshore wind stress off the Sumatra-Java coast contribute to the evolution of the Indian Ocean dipole (IOD) events.

Cost and Performance Report - Evaluating the Longevity and Hydraulic Performance of Permeable Reactive Barriers at Department of Defense Sites

DTIC Science & Technology

2002-12-01

methods, such as jetting, hydraulic fracturing , and vibratory beam, have been demonstrated at some sites, as they offer some cost advantages at deep sites...while still keeping the implementation cost relatively low. Beyond these depths, innovative methods (such as jetting and hydraulic fracturing ) can...type excavator and a trench-type barrier. For sites where the affected aquifer is deeper, innovative methods, such as jetting and hydraulic

Maximum entropy deconvolution of the optical jet of 3C 273

NASA Technical Reports Server (NTRS)

Evans, I. N.; Ford, H. C.; Hui, X.

1989-01-01

The technique of maximum entropy image restoration is applied to the problem of deconvolving the point spread function from a deep, high-quality V band image of the optical jet of 3C 273. The resulting maximum entropy image has an approximate spatial resolution of 0.6 arcsec and has been used to study the morphology of the optical jet. Four regularly-spaced optical knots are clearly evident in the data, together with an optical 'extension' at each end of the optical jet. The jet oscillates around its center of gravity, and the spatial scale of the oscillations is very similar to the spacing between the optical knots. The jet is marginally resolved in the transverse direction and has an asymmetric profile perpendicular to the jet axis. The distribution of V band flux along the length of the jet, and accurate astrometry of the optical knot positions are presented.

Publications of the Jet Propulsion Laboratory, 1981

NASA Technical Reports Server (NTRS)

1982-01-01

Over 500 externally distributed technical reports released during 1981 that resulted from scientific and engineering work performed, or managed by Jet Propulsion Laboratory are listed by primary author. Of the total number of entries, 311 are from the bimonthly Deep Space Network Progress Report, and its successor, the Telecommunications and Data Acquisition Progress Report.

Role of entrainment in convectively-coupled equatorial waves in an aquaplanet model

NASA Astrophysics Data System (ADS)

Peatman, Simon; Methven, John; Woolnough, Steve

2016-04-01

Equatorially-trapped waves are known to be one of the key phenomena in determining the distribution of convective precipitation in the tropics as well as being crucial to the dynamics of the Madden-Julian Oscillation. However, numerical weather prediction models struggle to sustain such waves for a realistic length of time, which has a significant impact on forecasting precipitation for regions such as equatorial Africa. It has been found in the past that enhancing the rate of moisture entrainment can improve certain aspects of parametrized tropical convection in climate models. A parameter F controls the rate of entrainment into the convective plume for deep- and mid-level convection, with F = 1 denoting the control case. Here it is found in an aquaplanet simulation that F > 1 produces more convective precipitation at all zonal wavenumbers. Furthermore, Kelvin wave activity increases for waves with low frequency and zonal wavenumber but is slightly suppressed for shorter, higher-frequency waves, and vice versa for westward-propagating waves. A change in entrainment rate also brings about a change in the basic state wind and humidity fields. Therefore, the question arises as to whether changes in wave activity are due directly to changes in the coupling to the humidity in the waves by entrainment or due to changes in the basic state. An experiment was devised in which the convective parametrization scheme is allowed to entrain a weighted sum of the environmental humidity and a prescribed zonally-symmetric climatology, with a parameter α controlling the extent of the decoupling from the environment. Experiments with this new mechanism in the parametrization scheme reveal a complex relationship. For long waves at low frequency (period > ˜13 days), removing zonal asymmetry in the humidity seen by the entrainment scheme has very little influence on the ratio of eastward- to westward-propagating power. At higher frequencies and zonal wavenumbers, removing this zonal asymmetry acts to suppress wave activity. Enhanced entrainment rate relative to the control case is also shown to slow the phase speed of Kelvin waves by around 20%. The phase speed depends also on the decoupling parameter α, with the minimum speed occurring around the special case α = 1 - 1/F , when the basic state humidity is entrained at the enhanced rate and perturbations from it are entrained at the control rate.

Using DSP technology to simplify deep space ranging

NASA Technical Reports Server (NTRS)

Bryant, S.

2000-01-01

Commercially available Digital Signal Processing (DSP) technology has enabled a new spacecraft ranging design. The new design reduces overall size, parts count, and complexity. The design implementation will also meet the Jet Propulsion Laboratory (JPL) requirements for both near-Earth and deep space ranging.

Structure and dynamics of the Benguela low-level coastal jet

NASA Astrophysics Data System (ADS)

Patricola, Christina M.; Chang, Ping

2017-10-01

Generations of coupled atmosphere-ocean general circulation models have been plagued by persistent warm sea surface temperature (SST) biases in the southeastern tropical Atlantic. The SST biases are most severe in the eastern boundary coastal upwelling region and are sensitive to surface wind stress and wind stress curl associated with the Benguela low-level coastal jet (BLLCJ), a southerly jet parallel to the Angola-Namibia coast. However, little has been documented about this atmospheric source of oceanic bias. Here we investigate the characteristics and dynamics of the BLLCJ using observations, reanalyses, and atmospheric model simulations. Satellite wind products and high-resolution reanalyses and models represent the BLLCJ with two near-shore maxima, one near the Angola-Benguela front (ABF) at 17.5°S, and the other near 25-27.5°S, whereas coarse resolution reanalyses and models represent the BLLCJ poorly with a single, broad, more offshore maximum. Model experiments indicate that convex coastal geometry near the ABF supports the preferred location of the BLLCJ northern maximum by supporting conditions for a hydraulic expansion fan. Intraseasonal variability of the BLLCJ is associated with large-scale variability in intensity and location of the South Atlantic subtropical high through modulation of the low-level zonal pressure gradient.

Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki

NASA Astrophysics Data System (ADS)

Horinouchi, Takeshi; Murakami, Shin-Ya; Satoh, Takehiko; Peralta, Javier; Ogohara, Kazunori; Kouyama, Toru; Imamura, Takeshi; Kashimura, Hiroki; Limaye, Sanjay S.; McGouldrick, Kevin; Nakamura, Masato; Sato, Takao M.; Sugiyama, Ko-Ichiro; Takagi, Masahiro; Watanabe, Shigeto; Yamada, Manabu; Yamazaki, Atsushi; Young, Eliot F.

2017-09-01

The Venusian atmosphere is in a state of superrotation where prevailing westward winds move much faster than the planet's rotation. Venus is covered with thick clouds that extend from about 45 to 70 km altitude, but thermal radiation emitted from the lower atmosphere and the surface on the planet's nightside escapes to space at narrow spectral windows of the near-infrared. The radiation can be used to estimate winds by tracking the silhouettes of clouds in the lower and middle cloud regions below about 57 km in altitude. Estimates of wind speeds have ranged from 50 to 70 m s-1 at low to mid-latitudes, either nearly constant across latitudes or with winds peaking at mid-latitudes. Here we report the detection of winds at low latitude exceeding 80 m s-1 using IR2 camera images from the Akatsuki orbiter taken during July and August 2016. The angular speed around the planetary rotation axis peaks near the equator, which we suggest is consistent with an equatorial jet, a feature that has not been observed previously in the Venusian atmosphere. The mechanism producing the jet remains unclear. Our observations reveal variability in the zonal flow in the lower and middle cloud region that may provide clues to the dynamics of Venus's atmospheric superrotation.

Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki.

PubMed

Horinouchi, Takeshi; Murakami, Shin-Ya; Satoh, Takehiko; Peralta, Javier; Ogohara, Kazunori; Kouyama, Toru; Imamura, Takeshi; Kashimura, Hiroki; Limaye, Sanjay S; McGouldrick, Kevin; Nakamura, Masato; Sato, Takao M; Sugiyama, Ko-Ichiro; Takagi, Masahiro; Watanabe, Shigeto; Yamada, Manabu; Yamazaki, Atsushi; Young, Eliot F

2017-01-01

The Venusian atmosphere is in a state of superrotation where prevailing westward winds move much faster than the planet's rotation. Venus is covered with thick clouds that extend from about 45 to 70 km altitude, but thermal radiation emitted from the lower atmosphere and the surface on the planet's night-side escapes to space at narrow spectral windows of near-infrared. The radiation can be used to estimate winds by tracking the silhouettes of clouds in the lower and middle cloud regions below about 57 km in altitude. Estimates of wind speeds have ranged from 50 to 70 m/s at low- to mid-latitudes, either nearly constant across latitudes or with winds peaking at mid-latitudes. Here we report the detection of winds at low latitude exceeding 80 m/s using IR2 camera images from the Akatsuki orbiter taken during July and August 2016. The angular speed around the planetary rotation axis peaks near the equator, which we suggest is consistent with an equatorial jet, a feature that has not been observed previously in the Venusian atmosphere. The mechanism producing the jet remains unclear. Our observations reveal variability in the zonal flow in the lower and middle cloud region that may provide new challenges and clues to the dynamics of Venus's atmospheric superrotation.

Investigations of needle-free jet injections.

PubMed

Schramm-Baxter, J R; Mitragotri, S

2004-01-01

Jet injection is a needle-free drug delivery method in which a high-speed stream of fluid impacts the skin and delivers drugs. Although a number of jet injectors are commercially available, especially for insulin delivery, they have a low market share compared to needles possibly due to occasional pain associated with jet injection. Jets employed by the traditional jet injectors penetrate deep into the dermal and sub-dermal regions where the nerve endings are abundantly located. To eliminate the pain associated with jet injections, we propose to utilize microjets that penetrate only into the superficial region of the skin. However, the choice of appropriate jet parameters for this purpose is challenging owing to the multiplicity of factors that determine the penetration depth. Here, we describe the dependence of jet injections into human skin on the power of the jet. Dermal delivery of liquid jets was quantified using two measurements, penetration of a radiolabeled solute, mannitol, into skin and the shape of jet dispersion in the skin which was visualized using sulforhodamine B. The dependence of the amount of liquid delivered in the skin and the geometric measurements of jet dispersion on nozzle diameter and jet velocity was captured by a single parameter, jet power.

Determination of the strong coupling constant from jet rates in deep inelastic scattering

NASA Astrophysics Data System (ADS)

Ahmed, T.; Aid, S.; Andreev, V.; Andrieu, B.; Appuhn, R.-D.; Arpagaus, M.; Babaev, A.; Baehr, J.; Bán, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Barth, M.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bergstein, H.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besançon, M.; Beyer, R.; Biddulph, P.; Bizot, J. C.; Blobel, V.; Borras, K.; Botterweck, F.; Boudry, V.; Braemer, A.; Brasse, F.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Brune, C.; Buchholz, R.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Clarke, D.; Clegg, A. B.; Clerbaux, B.; Colombo, M.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Courau, A.; Coutures, Ch.; Cozzika, G.; Criegee, L.; Cussans, D. G.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Danilov, M.; Dau, W. D.; Daum, K.; David, M.; Deffur, E.; Delcourt, B.; Del Buono, L.; De Roeck, A.; De Wolf, E. A.; Di Nezza, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Droutskoi, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Ehrlichmann, H.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Erdmann, W.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Gabathuler, E.; Gabathuler, K.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gebauer, M.; Gellrich, A.; Genzel, H.; Gerhards, R.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Gonzalez-Pineiro, B.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Hampel, M.; Hanlon, E. M.; Hapke, M.; Haynes, W. J.; Heatherington, J.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herma, R.; Herynek, I.; Hess, M. F.; Hildesheim, W.; Hill, P.; Hill, K. H.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Horisberger, R.; Huet, Ph.; Hufnagel, H.; Ibbotson, M.; Itterbeck, H.; Jabiol, M.-A.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Janoth, J.; Jansen, T.; Jönsson, L.; Johannsen, K.; Johnson, D. P.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kant, D.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Kaufmann, H. H.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuler, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Ko, W.; Köhler, T.; Köhne, J. H.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, U.; Krüner-Marquis, U.; Kubenka, J. P.; Küster, H.; Kuhlen, M.; Kurča, T.; Kurzhöfer, J.; Kuznik, B.; Lacour, D.; Lamarche, F.; Lander, R.; Landon, M. P. J.; Lange, W.; Lanius, P.; Laporte, J.-F.; Lebedev, A.; Leverenz, C.; Levonian, S.; Ley, Ch.; Lindner, A.; Lindström, G.; Linsel, F.; Lipinski, J.; List, B.; Loch, P.; Lohmander, H.; Lopez, G. C.; Lubimov, V.; Lüke, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, T.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Mercer, D.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Mikocki, S.; Milstead, D.; Moreau, F.; Morris, J. V.; Müller, G.; Müller, K.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Newman, P. R.; Newton, D.; Neyret, D.; Nguyen, H. K.; Niebergall, F.; Niebuhr, C.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg-Werther, M.; Oakden, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Panaro, E.; Panitch, A.; Pascaud, C.; Patel, G. D.; Peppel, E.; Perez, E.; Phillips, J. P.; Pichler, Ch.; Pitzl, D.; Pope, G.; Prell, S.; Prosi, R.; Rädel, G.; Raupach, F.; Reimer, P.; Reinshagen, S.; Ribarics, P.; Rick, H.; Riech, V.; Riedlberger, J.; Riess, S.; Rietz, M.; Robertson, S. M.; Robmann, P.; Roloff, H. E.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rüter, K.; Rusakov, S.; Rybicki, K.; Rylko, R.; Sahlmann, N.; Sanchez, E.; Sankey, D. P. C.; Savitsky, M.; Schacht, P.; Schiek, S.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmidt, G.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schwab, B.; Schwind, A.; Seehausen, U.; Sefkow, F.; Seidel, M.; Sell, R.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shooshtari, H.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Soloviev, Y.; Spitzer, H.; Starosta, R.; Steenbock, M.; Steffen, P.; Steinberg, R.; Stella, B.; Stephens, K.; Stier, J.; Stiewe, J.; Stösslein, U.; Strachota, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Tapprogge, S.; Taylor, R. E.; Tchernyshov, V.; Thiebaux, C.; Thompson, G.; Truöl, P.; Turnau, J.; Tutas, J.; Uelkes, P.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; Van Esch, P.; Van Mechelen, P.; Vartapetian, A.; Vazdik, Y.; Vecko, M.; Verrecchia, P.; Villet, G.; Wacker, K.; Wagener, A.; Wagener, M.; Walker, I. W.; Walther, A.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wellisch, H. P.; West, L. R.; Willard, S.; Winde, M.; Winter, G.-G.; Wright, A. E.; Wünsch, E.; Wulff, N.; Yiou, T. P.; Žáček, J.; Zarbock, D.; Zhang, Z.; Zhokin, A.; Zimmer, M.; Zimmermann, W.; Zomer, F.; Zuber, K.; H1 Collaboration

1995-02-01

Jet rates in deep inelastic electron proton scattering are studied with the H1 detector at HERA for momentum transfers squared between 10 and 4000 GeV 2. It is shown that they can be quantitatively described by perturbative QCD in next to leading order making use of the parton densities of the proton and with the strong coupling constant αs as a free parameter. The measured value, αs( MZ2) = 0.123 ± 0.018, is in agreement both with determinations from e+e- annihilation at LEP using the same observable and with the world average.

Effects of wind on the dynamics of the central jet during drop impact onto a deep-water surface

NASA Astrophysics Data System (ADS)

Liu, Xinan; Wang, An; Wang, Shuang; Dai, Dejun

2018-05-01

The cavity and central jet generated by the impact of a single water drop on a deep-water surface in a wind field are experimentally studied. Different experiments are performed by varying the impacting drop diameter and wind speed. The contour profile histories of the cavity (also called crater) and central jet (also called stalk) are measured in detail with a backlit cinematic shadowgraph technique. The results show that shortly after the drop hits the water surface an asymmetrical cavity appears along the wind direction, with a train of capillary waves on the cavity wall. This is followed by the formation of an inclined central jet at the location of the drop impact. It is found that the wind has little effect on the penetration depth of the cavity at the early stage of the cavity expansion, but markedly changes the capillary waves during the retraction of the cavity. The capillary waves in turn shift the position of the central jet formation leeward. The dynamics of the central jet are dominated by two mechanisms: (i) the oblique drop impact produced by the wind and (ii) the wind drag force directly acting on the jet. The maximum height of the central jet, called the stalk height, is drastically affected by the wind, and the nondimensional stalk height H /D decreases with increasing θ Re-1 , where D is the drop diameter, θ is the impingement angle of drop impact, and Re=ρaUwD /μa is the Reynolds number with air density ρa, wind speed Uw, and air viscosity μa.

The Correlation Between Tropical Convection and Upper Tropospheric Momentum Flux Convergence

NASA Technical Reports Server (NTRS)

O'CStarr, David; Boehm, Matthew T.

2003-01-01

In this study, the relationship between tropical convection and the meridional convergence of zonal momentum flux in the tropical upper troposphere is investigated using NOAA interpolated outgoing longwave radiation data and NCEP-NCAR reanalysis wind data. In particular, a variety of correlation coefficients are calculated between the data sets, both of which are filtered to isolate disturbances with frequencies and wavenumbers consistent with the Madden-Julian oscillation. The results show regions of significant correlation during each season, with the magnitude and area covered by significant correlation coefficients varying with season. Furthermore, it is found that the correlation structures look very similar to theoretical calculations of the atmospheric response to a region of tropical heating. This result suggests that tropical waves, in particular mixed Rossby-gravity waves, play an important role in the meridional transport zonal momentum into the deep tropical upper troposphere. Finally, these findings have implications to the generation of rising motion near the tropical tropopause, which in turn has ramifications for vertical moisture transport and tropopause cirrus formation.

Iris Transponder-Communications and Navigation for Deep Space

NASA Technical Reports Server (NTRS)

Duncan, Courtney B.; Smith, Amy E.; Aguirre, Fernando H.

2014-01-01

The Jet Propulsion Laboratory has developed the Iris CubeSat compatible deep space transponder for INSPIRE, the first CubeSat to deep space. Iris is 0.4 U, 0.4 kg, consumes 12.8 W, and interoperates with NASA's Deep Space Network (DSN) on X-Band frequencies (7.2 GHz uplink, 8.4 GHz downlink) for command, telemetry, and navigation. This talk discusses the Iris for INSPIRE, it's features and requirements; future developments and improvements underway; deep space and proximity operations applications for Iris; high rate earth orbit variants; and ground requirements, such as are implemented in the DSN, for deep space operations.

The transverse momentum distribution of hadrons within jets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Zhong -Bo; Liu, Xiaohui; Ringer, Felix

We study the transverse momentum distribution of hadrons within jets, where the transverse momentum is defined with respect to the standard jet axis. We consider the case where the jet substructure measurement is performed for an inclusive jet sample pp → jet + X. We demonstrate that this observable provides new opportunities to study transverse momentum dependent fragmentation functions (TMDFFs) which are currently poorly constrained from data, especially for gluons. The factorization of the cross section is obtained within Soft Collinear Effective Theory (SCET), and we show that the relevant TMDFFs are the same as for the more traditional processesmore » semi-inclusive deep inelastic scattering (SIDIS) and electron-positron annihilation. Different than in SIDIS, the observable for the in-jet fragmentation does not depend on TMD parton distribution functions which allows for a cleaner and more direct probe of TMDFFs. We present numerical results and compare to available data from the LHC.« less

The transverse momentum distribution of hadrons within jets

DOE PAGES

Kang, Zhong -Bo; Liu, Xiaohui; Ringer, Felix; ...

2017-11-13

We study the transverse momentum distribution of hadrons within jets, where the transverse momentum is defined with respect to the standard jet axis. We consider the case where the jet substructure measurement is performed for an inclusive jet sample pp → jet + X. We demonstrate that this observable provides new opportunities to study transverse momentum dependent fragmentation functions (TMDFFs) which are currently poorly constrained from data, especially for gluons. The factorization of the cross section is obtained within Soft Collinear Effective Theory (SCET), and we show that the relevant TMDFFs are the same as for the more traditional processesmore » semi-inclusive deep inelastic scattering (SIDIS) and electron-positron annihilation. Different than in SIDIS, the observable for the in-jet fragmentation does not depend on TMD parton distribution functions which allows for a cleaner and more direct probe of TMDFFs. We present numerical results and compare to available data from the LHC.« less

Diurnal, monthly and seasonal variation of mean winds in the MLT region observed over Kolhapur using MF radar

NASA Astrophysics Data System (ADS)

Sharma, A. K.; Gaikwad, H. P.; Ratnam, M. Venkat; Gurav, O. B.; Ramanjaneyulu, L.; Chavan, G. A.; Sathishkumar, S.

2018-04-01

Medium Frequency (MF) radar located at Kolhapur (16.8°N, 74.2°E) has been upgraded in August 2013. Since then continuous measurements of zonal and meridional winds are obtained covering larger altitudes from the Mesosphere and Lower Thermosphere (MLT) region. Diurnal, monthly and seasonal variation of these mean winds is presented in this study using four years (2013-2017) of observations. The percentage occurrence of radar echoes show maximum between 80 and 105 km. The mean meridional wind shows Annual Oscillation (AO) between 80 and 90 km altitudes with pole-ward motion during December solstice and equatorial motion during June solstice. Quasi-biennial oscillation (QBO) with weaker amplitudes are also observed between 90 and 104 km. Zonal winds show semi-annual oscillation (SAO) with westward winds during equinoxes and eastward winds during solstices between 80 and 90 km. AO with eastward winds during December solstice and westward wind in the June solstice is also observed in the mean zonal wind between 100 and 110 km. These results match well with that reported from other latitudes within Indian region between 80 and 90 km. However, above 90 km the results presented here provide true mean background winds for the first time over Indian low latitude region as the present station is away from equatorial electro-jet and are not contaminated by ionospheric processes. Further, the results presented earlier with an old version of this radar are found contaminated due to unknown reasons and are corrected in the present work. This upgraded MF radar together with other MLT radars in the Indian region forms unique network to investigate the vertical and lateral coupling.

An A-train climatology of extratropical cyclone clouds and precipitation

NASA Astrophysics Data System (ADS)

Naud, C. M.; Booth, J.; Del Genio, A. D.; van den Heever, S. C.; Posselt, D. J.

2016-12-01

It is demonstrated using the ERA-Interim product that synoptic to intraseasonal variabilities of extratropical circulation in the boreal storm track regions are strongly affected by the zonal convergence of the column-integrated eastward flux of local wave activity (LWA). In particular, from the multi-year daily samples of LWA fluxes, we find that the wintertime zonal LWA flux in the jet exit regions tends to maximize for an intermediate value of column-averaged LWA. This is because an increasing LWA decelerates the zonal flow, eventually weakening the eastward advection of LWA. From theory we argue that large wave events on the decreasing side of the flux curve with increasing LWA cannot be maintained as a stable steady state. Consistent with this argument, observed states corresponding to that side of flux curve often exhibit local wave breaking and blocking events. A close parallelism exists for the traffic flow problem, in which the traffic flux (traffic density times traffic speed) is often observed to maximize for an intermediate value of traffic density. This is because the traffic speed is controlled not only by the imposed speed limit but also by the traffic density — an increasingly heavy traffic slows down the flow naturally and eventually decreases the flux. Once the flux starts to decrease with an increasing traffic density, a traffic jam kicks in suddenly (Lighthill and Whitham 1955, Richards 1956). The above idea is demonstrated by a simple conceptual model based on the equivalent barotropic PV contour design (Nakamura and Huang 2017, JAS), which predicts a threshold of blocking onset. The idea also suggests that the LWA that gives the `flux capacity,' i.e., the maximum LWA flux at a given location, is a useful predictor of local wave breaking/block formation.

Brief Communication: Synoptic-scale differences between Sundowner and Santa Ana wind regimes in the Santa Ynez Mountains, California

NASA Astrophysics Data System (ADS)

Hatchett, Benjamin J.; Smith, Craig M.; Nauslar, Nicholas J.; Kaplan, Michael L.

2018-02-01

Downslope Sundowner winds in southern California's Santa Ynez Mountains favor wildfire growth. To explore differences between Sundowners and Santa Ana winds (SAWs), we use surface observations from 1979 to 2014 to develop a climatology of extreme Sundowner days. The climatology was compared to an existing SAW index from 1979 to 2012. Sundowner (SAW) occurrence peaks in late spring (winter). SAWs demonstrate amplified 500 hPa geopotential heights over western North America and anomalous positive inland mean sea-level pressures. Sundowner-only conditions display zonal 500 hPa flow and negative inland sea-level pressure anomalies. A low-level northerly coastal jet is present during Sundowners but not SAWs.

Comparison between reference atmosphere winds and radar winds from selected locations

NASA Technical Reports Server (NTRS)

Manson, A. H.; Meek, C. E.; Vincent, R. A.; Craig, R. L.; Phillips, A.; Fraser, G. J.; Smith, M. J.; Fellous, J. L.; Massebeuf, M.; Chandra, S.

1990-01-01

Zonal and meridional 60-110-km wind profiles obtained by radar measurements at Saskatoon, Adelaide, Christchurch, Puerto Rico, and Mawson are presented graphically and compared with those from the COSPAR International Reference Atmosphere (CIRA) for 1986. Good general agreement is found below about 80 km, but above 80 km the CIRA 1986 models show discrepancies, including: (1) no spring tongue of weak westward flow at latitudes 20-70 deg; (2) too strong an eastward flow at 20-52 deg in summer; (3) too great reversal heights at 35-43 deg N in summer; and (4) too strong (by a factor of 2) summer and winter jets at 65-70 deg N.

Dynamically Intuitive and Potentially Predicatable Three-Dimensional Structures in the Low Frequency Flow Variability of the Extratropical Northern Hemisphere

NASA Astrophysics Data System (ADS)

Wettstein, J. J.; Li, C.; Bradshaw, S.

2016-12-01

Canonical tropospheric climate variability patterns and their corresponding indices are ubiquitous, yet a firm dynamical interpretation has remained elusive for many of even the leading extratropical patterns. Part of the lingering difficulty in understanding and predicting atmospheric low frequency variability is the fact that the identification itself of the different patterns is indistinct. This study characterizes three-dimensional structures in the low frequency variability of the extratropical zonal wind field within the entire period of record of the ERA-Interim reanalysis and suggests the foundations for a new paradigm in identifying and predicting extratropical atmospheric low-frequency variability. In concert with previous results, there is a surprisingly rich three-dimensional structure to the variance of the zonal wind field that is not (cannot be) captured by traditional identification protocols that explore covariance of pressure in the lower troposphere, flow variability in the zonal mean or, for that matter, in any variable on any planar surface. Correspondingly, many of the pressure-based canonical indices of low frequency atmospheric variability exhibit inconsistent relationships to physically intuitive reorganizations of the subtropical and polar front jets and with other forcing mechanisms. Different patterns exhibit these inconsistencies to a greater or lesser extent. The three-dimensional variance of the zonal wind field is, by contrast, naturally organized around dynamically intuitive atmospheric redistributions that have a surprisingly large amount of physically intuitive information in the vertical. These conclusions are robust in a variety of seasons and also in intra-seasonal and inter-annual explorations. Similar results and conclusions are also derived using detrended data, other reanalyses, and state-of-the-art coupled climate model output. In addition to providing a clearer perspective on the distinct three-dimensional patterns of atmospheric low frequency variability, the time evolution and potential predictability of the resultant patterns can be explored with much greater clarity because of an intrinsic link between the patterns and the requisite conservation of momentum (i.e. to the primitive equations and candidate forcing mechanisms).

Quasi-12 h inertia-gravity waves in the lower mesosphere observed by the PANSY radar at Syowa Station (39.6° E, 69.0° S)

NASA Astrophysics Data System (ADS)

Shibuya, Ryosuke; Sato, Kaoru; Tsutsumi, Masaki; Sato, Toru; Tomikawa, Yoshihiro; Nishimura, Koji; Kohma, Masashi

2017-05-01

The first observations made by a complete PANSY radar system (Program of the Antarctic Syowa MST/IS Radar) installed at Syowa Station (39.6° E, 69.0° S) were successfully performed from 16 to 24 March 2015. Over this period, quasi-half-day period (12 h) disturbances in the lower mesosphere at heights of 70 to 80 km were observed. Estimated vertical wavelengths, wave periods and vertical phase velocities of the disturbances were approximately 13.7 km, 12.3 h and -0.3 m s-1, respectively. Under the working hypothesis that such disturbances are attributable to inertia-gravity waves, wave parameters are estimated using a hodograph analysis. The estimated horizontal wavelengths are longer than 1100 km, and the wavenumber vectors tend to point northeastward or southwestward. Using the nonhydrostatic numerical model with a model top of 87 km, quasi-12 h disturbances in the mesosphere were successfully simulated. We show that quasi-12 h disturbances are due to wave-like disturbances with horizontal wavelengths longer than 1400 km and are not due to semidiurnal migrating tides. Wave parameters, such as horizontal wavelengths, vertical wavelengths and wave periods, simulated by the model agree well with those estimated by the PANSY radar observations under the abovementioned assumption. The parameters of the simulated waves are consistent with the dispersion relationship of the inertia-gravity wave. These results indicate that the quasi-12 h disturbances observed by the PANSY radar are attributable to large-scale inertia-gravity waves. By examining a residual of the nonlinear balance equation, it is inferred that the inertia-gravity waves are likely generated by the spontaneous radiation mechanism of two different jet streams. One is the midlatitude tropospheric jet around the tropopause while the other is the polar night jet. Large vertical fluxes of zonal and meridional momentum associated with large-scale inertia-gravity waves are distributed across a slanted region from the midlatitude lower stratosphere to the polar mesosphere in the meridional cross section. Moreover, the vertical flux of the zonal momentum has a strong negative peak in the mesosphere, suggesting that some large-scale inertia-gravity waves originate in the upper stratosphere.

GCM simulations of intraseasonal variability in the Pacific/North American region

NASA Technical Reports Server (NTRS)

Schubert, Siegfried; Suarez, Max; Park, Chung-Kyu; Moorthi, Shrinivas

1993-01-01

General circulation model (GCM) simulations of low-frequency variability with time scales of 20 to 70 days are analyzed for the Pacific sector during boreal winter. The GCM's leading mode in the upper-tropospheric zonal wind is associated with fluctuations of the East Asian jet; this mode resembles, in both structure and amplitude, the Pacific/North American (PNA) pattern found in the observations on these time scales. In both the model and observations, the PNA anomaly is characterized by: (1) a linear balance in the upper-tropospheric vorticity budget with no significant Rossby wave source in the tropics, (2) a barotropic conversion of kinetic energy from the time mean Pacific jet, and (3) a north/south displacement of the Pacific storm track. In the GCM, the latter is associated with synoptic eddy heat flux and latent heat anomalies that appear to contribute to a strong lower-tropospheric source of wave activity over the North Pacific. This is in contrast to the observations, which show only a weak source of wave activity in this region.

Longitudinal Double-Spin Asymmetry for Inclusive Jet Production in p→+p→ Collisions at s=200GeV

NASA Astrophysics Data System (ADS)

Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Baumgart, S.; Belaga, V. V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Benedosso, F.; Betts, R. R.; Bhardwaj, S.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Blyth, S.-L.; Bombara, M.; Bonner, B. E.; Botje, M.; Bouchet, J.; Brandin, A. V.; Burton, T. P.; Bystersky, M.; Cai, X. Z.; Caines, H.; Calderón de La Barca Sánchez, M.; Callner, J.; Catu, O.; Cebra, D.; Cervantes, M. C.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, S. U.; Clarke, R. F.; Codrington, M. J. M.; Coffin, J. P.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; de Moura, M. M.; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; Didenko, L.; Dietel, T.; Djawotho, P.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, F.; Dunin, V. B.; Dunlop, J. C.; Dutta Mazumdar, M. R.; Edwards, W. R.; Efimov, L. G.; Elhalhuli, E.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C. A.; Gaillard, L.; Ganti, M. S.; Garcia-Solis, E.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. N.; Gos, H.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S. M.; Guimaraes, K. S. F. F.; Gupta, A.; Gupta, N.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; He, W.; Heinz, M.; Henry, T. W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D. J.; Hollis, R. S.; Horner, M. J.; Huang, H. Z.; Hughes, E. W.; Humanic, T. J.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jones, P. G.; Judd, E. G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V. Yu.; Kiryluk, J.; Kisiel, A.; Kislov, E. M.; Klein, S. R.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kouchpil, V.; Kowalik, K. L.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Kuhn, C.; Kulikov, A. I.; Kumar, A.; Kurnadi, P.; Kuznetsov, A. A.; Lamont, M. A. C.; Landgraf, J. M.; Lange, S.; Lapointe, S.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Lehocka, S.; Levine, M. J.; Li, C.; Li, Q.; Li, Y.; Lin, G.; Lin, X.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ludlam, T.; Lynn, D.; Ma, G. L.; Ma, J. G.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Martin, L.; Matis, H. S.; Matulenko, Yu. A.; McShane, T. S.; Meschanin, A.; Millane, J.; Miller, M. L.; Minaev, N. G.; Mioduszewski, S.; Mischke, A.; Mitchell, J.; Mohanty, B.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Nepali, C.; Netrakanti, P. K.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okorokov, V.; Olson, D.; Pachr, M.; Pal, S. K.; Panebratsev, Y.; Pavlinov, A. I.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Planinic, M.; Pluta, J.; Poljak, N.; Porile, N.; Poskanzer, A. M.; Potekhin, M.; Potrebenikova, E.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Putschke, J.; Qattan, I. A.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Relyea, D.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Sahoo, R.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sarsour, M.; Sazhin, P. S.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shen, W. Q.; Shimanskiy, S. S.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Skoby, M. J.; Smirnov, N.; Snellings, R.; Sorensen, P.; Sowinski, J.; Speltz, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, T. D. S.; Staszak, D.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Z.; Surrow, B.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Timoshenko, S.; Tokarev, M.; Trainor, T. A.; Tram, V. N.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; van Buren, G.; van der Kolk, N.; van Leeuwen, M.; Vander Molen, A. M.; Varma, R.; Vasilevski, I. M.; Vasiliev, A. N.; Vernet, R.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Waggoner, W. T.; Wang, F.; Wang, G.; Wang, J. S.; Wang, X. L.; Wang, Y.; Webb, J. C.; Westfall, G. D.; Whitten, C., Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, J.; Wu, Y.; Xu, N.; Xu, Q. H.; Xu, Z.; Yepes, P.; Yoo, I.-K.; Yue, Q.; Yurevich, V. I.; Zawisza, M.; Zhan, W.; Zhang, H.; Zhang, W. M.; Zhang, Y.; Zhang, Z. P.; Zhao, Y.; Zhong, C.; Zhou, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zubarev, A. N.; Zuo, J. X.

2008-06-01

We report a new STAR measurement of the longitudinal double-spin asymmetry ALL for inclusive jet production at midrapidity in polarized p+p collisions at a center-of-mass energy of s=200GeV. The data, which cover jet transverse momenta 5

The Status of Ka-Band Communications for Future Deep Space Missions

NASA Technical Reports Server (NTRS)

Edwards, C.; Deutsch, L.; Gatti, M.; Layland, J.; Perret, J.; Stelzried, C.

1997-01-01

Over the past decade, the Jet Propulsion Laboratory's Telecommunications and Mission Operations Directorate has invested in a variety of technologies, targeted at both the flight and ground sides of the communications link, with the goal of developing a Ka-band (32 GHz) communications capability for future deep space missions.

Improvements in Modeling the Collimated Jets of Comet 19P/Borrelly from the Stereo Images of the Deep Space 1 Flyby

NASA Astrophysics Data System (ADS)

Melville, Kenneth J.; Farnham, T.; Hoban, S.

2010-10-01

On September 22, 2001, the spacecraft Deep Space 1 (DS1), which was primarily designed for testing advanced technologies in space, preformed an extended mission flyby of the comet 19P/Borrelly. This encounter provided scientists with the best images taken of a comet. These images from the DS1 Miniature Integrated Camera and Spectrometer (MICAS) instrument show features of comet Borrelly's surface; collimated dust jets escaping the nucleus, and the coma of gas and dust that surrounds the nucleus. Properties of the jet, such as rate and angle of expansion have been measured accurately due to the jet's geometric structure and position on the rotation axis of the comet. These measurements have been taken for several points along the spacecrafts approach, flyby, and from additional McDonald ground based observatory images. A model of the jet with similar geometry has been constructed in order to reproduce the observational data found in the flyby images. Other proposed models are tested as well. Once these models has been adjusted to replicate the data, they can be used to investigate the collimation mechanism below the comets surface producing the jet. Comet 19P/Borrelly is the idea test for this model due to the simple structure of the jet, as well as the wide variety of angles and observation times. Using information from this model, scientists may be able to make new assumptions on the composition and physical structure of other comets. This research was supported by the NASA Planetary Data System: Small Bodies Node, and College Student Investigator Program at UMBC Goddard Earth Sciences & Technology Center.

On the composite response of the MLT to major sudden stratospheric warming events with elevated stratopause

NASA Astrophysics Data System (ADS)

Limpasuvan, Varavut; Orsolini, Yvan J.; Chandran, Amal; Garcia, Rolando R.; Smith, Anne K.

2016-05-01

Based on a climate-chemistry model (constrained by reanalyses below ~50 km), the zonal-mean composite response of the mesosphere and lower thermosphere (MLT) to major sudden stratospheric warming events with elevated stratopauses demonstrates the role of planetary waves (PWs) in driving the mean circulation in the presence of gravity waves (GWs), helping the polar vortex recover and communicating the sudden stratospheric warming (SSW) impact across the equator. With the SSW onset, strong westward PW drag appears above 80 km primarily from the dissipation of wave number 1 perturbations with westward period of 5-12 days, generated from below by the unstable westward polar stratospheric jet that develops as a result of the SSW. The filtering effect of this jet also allows eastward propagating GWs to saturate in the winter MLT, providing eastward drag that promotes winter polar mesospheric cooling. The dominant PW forcing translates to a net westward drag above the eastward mesospheric jet, which initiates downwelling over the winter pole. As the eastward polar stratospheric jet returns, this westward PW drag persists above 80 km and acts synergistically with the return of westward GW drag to drive a stronger polar downwelling that warms the pole adiabatically and helps reform the stratopause at an elevated altitude. With the polar wind reversal during the SSW onset, the westward drag by the quasi-stationary PW in the winter stratosphere drives an anomalous equatorial upwelling and cooling that enhance tropical stratospheric ozone. Along with equatorial wind anomalies, this ozone enhancement subsequently amplifies the migrating semidiurnal tide amplitude in the winter midlatitudes.

Climate predictability and prediction skill on seasonal time scales over South America from CHFP models

NASA Astrophysics Data System (ADS)

Osman, Marisol; Vera, C. S.

2017-10-01

This work presents an assessment of the predictability and skill of climate anomalies over South America. The study was made considering a multi-model ensemble of seasonal forecasts for surface air temperature, precipitation and regional circulation, from coupled global circulation models included in the Climate Historical Forecast Project. Predictability was evaluated through the estimation of the signal-to-total variance ratio while prediction skill was assessed computing anomaly correlation coefficients. Both indicators present over the continent higher values at the tropics than at the extratropics for both, surface air temperature and precipitation. Moreover, predictability and prediction skill for temperature are slightly higher in DJF than in JJA while for precipitation they exhibit similar levels in both seasons. The largest values of predictability and skill for both variables and seasons are found over northwestern South America while modest but still significant values for extratropical precipitation at southeastern South America and the extratropical Andes. The predictability levels in ENSO years of both variables are slightly higher, although with the same spatial distribution, than that obtained considering all years. Nevertheless, predictability at the tropics for both variables and seasons diminishes in both warm and cold ENSO years respect to that in all years. The latter can be attributed to changes in signal rather than in the noise. Predictability and prediction skill for low-level winds and upper-level zonal winds over South America was also assessed. Maximum levels of predictability for low-level winds were found were maximum mean values are observed, i.e. the regions associated with the equatorial trade winds, the midlatitudes westerlies and the South American Low-Level Jet. Predictability maxima for upper-level zonal winds locate where the subtropical jet peaks. Seasonal changes in wind predictability are observed that seem to be related to those associated with the signal, especially at the extratropics.

Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki

PubMed Central

Horinouchi, Takeshi; Murakami, Shin-ya; Satoh, Takehiko; Peralta, Javier; Ogohara, Kazunori; Kouyama, Toru; Imamura, Takeshi; Kashimura, Hiroki; Limaye, Sanjay S.; McGouldrick, Kevin; Nakamura, Masato; Sato, Takao M.; Sugiyama, Ko-ichiro; Takagi, Masahiro; Watanabe, Shigeto; Yamada, Manabu; Yamazaki, Atsushi; Young, Eliot F.

2018-01-01

The Venusian atmosphere is in a state of superrotation where prevailing westward winds move much faster than the planet’s rotation. Venus is covered with thick clouds that extend from about 45 to 70 km altitude, but thermal radiation emitted from the lower atmosphere and the surface on the planet’s night-side escapes to space at narrow spectral windows of near-infrared. The radiation can be used to estimate winds by tracking the silhouettes of clouds in the lower and middle cloud regions below about 57 km in altitude. Estimates of wind speeds have ranged from 50 to 70 m/s at low- to mid-latitudes, either nearly constant across latitudes or with winds peaking at mid-latitudes. Here we report the detection of winds at low latitude exceeding 80 m/s using IR2 camera images from the Akatsuki orbiter taken during July and August 2016. The angular speed around the planetary rotation axis peaks near the equator, which we suggest is consistent with an equatorial jet, a feature that has not been observed previously in the Venusian atmosphere. The mechanism producing the jet remains unclear. Our observations reveal variability in the zonal flow in the lower and middle cloud region that may provide new challenges and clues to the dynamics of Venus’s atmospheric superrotation. PMID:29887914

Go Long, Go Deep: Finding Optical Jet Breaks for Swift-Era GRBs with the LBT

NASA Astrophysics Data System (ADS)

Dai, X.; Garnavich, P. M.; Prieto, J. L.; Stanek, K. Z.; Kochanek, C. S.; Bechtold, J.; Bouche, N.; Buschkamp, P.; Diolaiti, E.; Fan, X.; Giallongo, E.; Gredel, R.; Hill, J. M.; Jiang, L.; McClelland, C.; Milne, P.; Pedichini, F.; Pogge, R. W.; Ragazzoni, R.; Rhoads, J.; Smareglia, R.; Thompson, D.; Wagner, R. M.

2008-08-01

Using the 8.4 m Large Binocular Telescope, we observed six GRB afterglows from 2.8 hr to 30.8 days after the burst triggers to systematically probe the late-time behaviors of afterglows including jet breaks, flares, and supernova bumps. We detected five afterglows with Sloan r' magnitudes ranging from 23.0 to 26.3 mag. The depth of our observations allows us to extend the temporal baseline for measuring jet breaks by another decade in timescale. We detected two jet breaks and a third candidate, all of which are not detectable without deep, late-time optical observations. In the other three cases, we do not detect the jet breaks either because of contamination from the host galaxy light, the presence of a supernova bump, or the intrinsic faintness of the optical afterglow. This suggests that the basic picture that GRBs are collimated is still valid and that the apparent lack of Swift jet breaks is due to poorly sampled afterglow light curves, particularly at late times. Based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; the Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, the University of Minnesota, and the University of Virginia.

Which way will the circulation shift in a changing climate? Possible nonlinearity of extratropical cloud feedbacks

NASA Astrophysics Data System (ADS)

Tandon, Neil F.; Cane, Mark A.

2017-06-01

In a suite of idealized experiments with the Community Atmospheric Model version 3 coupled to a slab ocean, we show that the atmospheric circulation response to CO2 increase is sensitive to extratropical cloud feedback that is potentially nonlinear. Doubling CO2 produces a poleward shift of the Southern Hemisphere (SH) midlatitude jet that is driven primarily by cloud shortwave feedback and modulated by ice albedo feedback, in agreement with earlier studies. More surprisingly, for CO2 increases smaller than 25 %, the SH jet shifts equatorward. Nonlinearities are also apparent in the Northern Hemisphere, but with less zonal symmetry. Baroclinic instability theory and climate feedback analysis suggest that as the CO2 forcing amplitude is reduced, there is a transition from a regime in which cloud and circulation changes are largely decoupled to a regime in which they are highly coupled. In the dynamically coupled regime, there is an apparent cancellation between cloud feedback due to warming and cloud feedback due to the shifting jet, and this allows the ice albedo feedback to dominate in the high latitudes. The extent to which dynamical coupling effects exceed thermodynamic forcing effects is strongly influenced by cloud microphysics: an alternate model configuration with slightly increased cloud liquid (LIQ) produces poleward jet shifts regardless of the amplitude of CO2 forcing. Altering the cloud microphysics also produces substantial spread in the circulation response to CO2 doubling: the LIQ configuration produces a poleward SH jet shift approximately twice that produced under the default configuration. Analysis of large ensembles of the Canadian Earth System Model version 2 demonstrates that nonlinear, cloud-coupled jet shifts are also possible in comprehensive models. We still expect a poleward trend in SH jet latitude for timescales on which CO2 increases by more than 25 %. But on shorter timescales, our results give good reason to expect significant equatorward deviations. We also discuss the implications for understanding the circulation response to small external forcings from other sources, such as the solar cycle.

The GalileoJupiter Probe Doppler Wind Experiment

NASA Astrophysics Data System (ADS)

Atkinson, D. H.

2001-09-01

The GalileoJupiter atmospheric entry probe was launched along with the Galileoorbiter spacecraft from Cape Canaveral in Florida, USA, on October 18, 1989. Following a cruise of greater than six years, the probe arrived at Jupiter on December 7, 1995. During its 57-minute descent, instruments on the probe studied the atmospheric composition and structure, the clouds, lightning, and energy structure of the upper Jovian atmosphere. One of the two radio channels over which the experiment data was transmitted to the orbiter was driven by an ultrastable oscillator. All motions of the probe and orbiter, including the speed of probe descent, Jupiter's rotation, and the atmospheric winds, contributed to a Doppler shift of the probe radio frequency. By accurately measuring the frequency of the probe radio signal, an accurate time history of the probe-orbiter relative motions could be reconstructed. Knowledge of the nominal probe and orbiter trajectories allowed the nominal Doppler shift to be removed from the probe radio frequency leaving a measurable frequency residual arising primarily from the zonal winds in Jupiter's atmosphere, and micromotions of the probe arising from probe spin, swing under the parachute, atmospheric turbulence, and aerodynamic effects. Assuming that the zonal horizontal winds dominate the residual probe motion, a profile of frequency residuals was generated. Inversion of the frequency residuals resulted in the first in situ measurements of the vertical profile of Jupiter's deep zonal winds. It is found that beneath 700 mb, the winds are strong and prograde, rising rapidly to 170 m/s between 1 and 4 bars. Beneath 4 bars to 21 bars, the depth at which the link with the probe was lost, the winds remain constant and strong. When corrections for the high temperatures encountered by the probe are considered, there is no evidence of diminishing or strengthening of the zonal winds in the deepest regions explored by the Galileoprobe. Following the wind recovery, the frequency residuals offer tantalizing clues to microstructure in the atmospheric dynamics, including turbulence and wave motion.

Impact of a single drop on the same liquid: formation, growth and disintegration of jets

NASA Astrophysics Data System (ADS)

Agbaglah, G. Gilou; Deegan, Robert

2015-11-01

One of the simplest splashing scenarios results from the impact of a single drop on on the same liquid. The traditional understanding of this process is that the impact generates a jet that later breaks up into secondary droplets. Recently it was shown that even this simplest of scenarios is more complicated than expected because multiple jets can be generated from a single impact event and there are bifurcations in the multiplicity of jets. First, we study the formation, growth and disintegration of jets following the impact of a drop on a thin film of the same liquid using a combination of numerical simulations and linear stability theory. We obtain scaling relations from our simulations and use these as inputs to our stability analysis. We also use experiments and numerical simulations of a single drop impacting on a deep pool to examine the bifurcation from a single jet into two jets. Using high speed X-ray imaging methods we show that vortex separation within the drop leads to the formation of a second jet long after the formation of the ejecta sheet.

Grid generation by elliptic partial differential equations for a tri-element Augmentor-Wing airfoil

NASA Technical Reports Server (NTRS)

Sorenson, R. L.

1982-01-01

Two efforts to numerically simulate the flow about the Augmentor-Wing airfoil in the cruise configuration using the GRAPE elliptic partial differential equation grid generator algorithm are discussed. The Augmentor-Wing consists of a main airfoil with a slotted trailing edge for blowing and two smaller airfoils shrouding the blowing jet. The airfoil and the algorithm are described, and the application of GRAPE to an unsteady viscous flow simulation and a transonic full-potential approach is considered. The procedure involves dividing a complicated flow region into an arbitrary number of zones and ensuring continuity of grid lines, their slopes, and their point distributions across the zonal boundaries. The method for distributing the body-surface grid points is discussed.

The life cycles of persistent anomalies and blocking over the North Pacific

NASA Technical Reports Server (NTRS)

Dole, Randall M.

1986-01-01

The evolution of persistent anomaly patterns over the central North Pacific is investigated. Composite time evolution fields of the 500-mbar anomaly patterns are constructed from low-pass and unfiltered height anomaly data; the time scales for the development and decay of these persistent anomalies are analyzed. The relationship between zonal flow in the Pacific jet region and the development of the anomaly patterns is examined. The effect of baroclinic instabilities on the development of the anomalies is studied. The vertical structure and synoptic characteristics of the evolution of the anomalies are described. It is noted that the initial rapid growth of the main center may be associated with a propagating, intensifying, synoptic-scale disturbance which originates in the midlatitudes over eastern Asia.

Southern Ocean eddy compensation in a forced eddy-resolving GCM

NASA Astrophysics Data System (ADS)

Bruun Poulsen, Mads; Jochum, Markus; Eden, Carsten; Nuterman, Roman

2017-04-01

Contemporary eddy-resolving model studies have demonstrated that the common parameterisation of isopycnal mixing in the ocean is subject to limitations in the Southern Ocean where the mesoscale eddies are of leading order importance to the dynamics. We here present forced simulations from the Community Earth System Model on a global {1/10}° and 1° horizontal grid, the latter employing an eddy parameterisation, where the strength of the zonal wind stress south of 25°S has been varied. With a 50% zonally symmetric increase of the wind stress, we show that the two models arrive at two radically different solutions in terms of the large-scale circulation, with an increase of the deep inflow of water to the Southern Ocean at 40°S by 50% in the high resolution model against 20% at coarse resolution. Together with a weaker vertical displacement of the pycnocline in the 1° model, these results suggest that the parameterised eddies have an overly strong compensating effect on the water mass transformation compared to the explicit eddies. Implications for eddy mixing parameterisations will be discussed.

Maintenance of time and frequency in the Jet Propulsion Laboratory's Deep Space Network using the Global Positioning System

NASA Technical Reports Server (NTRS)

Clements, P. A.; Borutzki, S. E.; Kirk, A.

1984-01-01

The Deep Space Network (DSN), managed by the Jet Propulsion Laboratory for NASA, must maintain time and frequency within specified limits in order to accurately track the spacecraft engaged in deep space exploration. Various methods are used to coordinate the clocks among the three tracking complexes. These methods include Loran-C, TV Line 10, Very Long Baseline Interferometry (VLBI), and the Global Positioning System (GPS). Calculations are made to obtain frequency offsets and Allan variances. These data are analyzed and used to monitor the performance of the hydrogen masers that provide the reference frequencies for the DSN Frequency and Timing System (DFT). Areas of discussion are: (1) a brief history of the GPS timing receivers in the DSN, (2) a description of the data and information flow, (3) data on the performance of the DSN master clocks and GPS measurement system, and (4) a description of hydrogen maser frequency steering using these data.

Nuclear Thermal Rocket - Arc Jet Integrated System Model

NASA Technical Reports Server (NTRS)

Taylor, Brian D.; Emrich, William

2016-01-01

In the post-shuttle era, space exploration is moving into a new regime. Commercial space flight is in development and is planned to take on much of the low earth orbit space flight missions. With the development of a heavy lift launch vehicle, the Space Launch, System, NASA has become focused on deep space exploration. Exploration into deep space has traditionally been done with robotic probes. More ambitious missions such as manned missions to asteroids and Mars will require significant technology development. Propulsion system performance is tied to the achievability of these missions and the requirements of other developing technologies that will be required. Nuclear thermal propulsion offers a significant improvement over chemical propulsion while still achieving high levels of thrust. Opportunities exist; however, to build upon what would be considered a standard nuclear thermal engine to attain improved performance, thus further enabling deep space missions. This paper discuss the modeling of a nuclear thermal system integrated with an arc jet to further augment performance. The performance predictions and systems impacts are discussed.

The Deep Meridional Overturning Circulation in the Indian Ocean Inferred from the GECCO Synthesis

NASA Astrophysics Data System (ADS)

Wang, W.; Koehl, A.; Stammer, D.

2012-04-01

The meridional overturning circulation in the Indian Ocean and its temporal variability in the GECCO ocean synthesis are being investigated. An analysis of the integrated circulation in different layers suggests that, on time average, 2.1 Sv enter the Indian Ocean in the bottom layer (>3200m) from the south and that 12.3 Sv leave the Indian Ocean in the upper and intermediate layers (<1500m), composed of the up-welled bottom layer inflow water, augmented by 9.6 Sv Indonesian Throughflow (ITF) water. The GECCO time-mean results differ significantly from those obtained by box inverse models, which, being based on individual hydrographic sections, are susceptible to aliasing. The GECCO solution has a large seasonal variation in its meridional overturning caused by the seasonal reversal of monsoon-related wind stress forcing. Associated seasonal variations of the deep meridional overturning range from -7 Sv in boreal winter to 3 Sv in summer. In addition, the upper and bottom transports across 34°S section show pronounced interannual variability with roughly biennial variations superimposed by strong anomalies during each La Niña phase as well as the ITF, which mainly affect the upper layer transports. On decadal and longer timescale, the meridional overturning variability as well as long-term trends differ before and after 1980. Notably, our analysis shows a rather stable trend for the period 1960-1979 and significant changes in the upper and bottom layer for the period 1980-2001. By means of a multivariate EOF analysis, the importance of Ekman dynamics as driving forces of the deep meridional overturning of the Indian Ocean on the interannual timescale is highlighted. The leading modes of the zonal and meridional wind stress favour a basin-wide meridional overturning mode via Ekman upwelling or downwelling mostly in the central and eastern Indian Ocean. Moreover, tropical zonal wind stress along the equator and alongshore wind stress off the Sumatra-Java coast contributes to evolution of IOD events.

Low Q2 jet production at HERA and virtual photon structure

NASA Astrophysics Data System (ADS)

H1 Collaboration; Adloff, C.; Aid, S.; Anderson, M.; Andreev, V.; Andrieu, B.; Arkadov, V.; Arndt, C.; Ayyaz, I.; Babaev, A.; Bähr, J.; Bán, J.; Baranov, P.; Barrelet, E.; Barschke, R.; Bartel, W.; Bassler, U.; Beck, M.; Behrend, H.-J.; Beier, C.; Belousov, A.; Berger, Ch.; Bernardi, G.; Bertrand-Coremans, G.; Beyer, R.; Biddulph, P.; Bizot, J. C.; Borras, K.; Botterweck, F.; Boudry, V.; Bourov, S.; Braemer, A.; Braunschweig, W.; Brisson, V.; Brown, D. P.; Brückner, W.; Bruel, P.; Bruncko, D.; Brune, C.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Calvet, D.; Campbell, A. J.; Carli, T.; Charlet, M.; Clarke, D.; Clerbaux, B.; Cocks, S.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Cousinou, M.-C.; Cox, B. E.; Cozzika, G.; Cussans, D. G.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; de Roeck, A.; de Wolf, E. A.; Delcourt, B.; Dirkmann, M.; Dixon, P.; Dlugosz, W.; Donovan, K. T.; Dowell, J. D.; Droutskoi, A.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Elsen, E.; Erdmann, M.; Fahr, A. B.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Formánek, J.; Foster, J. M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Gaede, F.; Garvey, J.; Gayler, J.; Gebauer, M.; Gerhards, R.; Glazov, A.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Gonzalez-Pineiro, B.; Gorelov, I.; Grab, C.; Grässler, H.; Greenshaw, T.; Griffiths, R. K.; Grindhammer, G.; Gruber, A.; Gruber, C.; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, T.; Hampel, M.; Haynes, W. J.; Heinemann, B.; Heinzelmann, G.; Henderson, R. C. W.; Hengstmann, S.; Henschel, H.; Herynek, I.; Hess, M. F.; Hewitt, K.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Höppner, M.; Hoffmann, D.; Holtom, T.; Horisberger, R.; Hudgson, V. L.; Hütte, M.; Ibbotson, M.; Isolarş Sever, Ç.; Itterbeck, H.; Jacquet, M.; Jaffre, M.; Janoth, J.; Jansen, D. M.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kalmus, P. I. P.; Kander, M.; Kant, D.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kaufmann, O.; Kausch, M.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Köhne, J. H.; Kolanoski, H.; Kolya, S. D.; Korbel, V.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Küpper, A.; Küster, H.; Kuhlen, M.; Kurča, T.; Laforge, B.; Lahmann, R.; Landon, M. P. J.; Lange, W.; Langenegger, U.; Lebedev, A.; Lehner, F.; Lemaitre, V.; Levonian, S.; Lindstroem, M.; Lipinski, J.; List, B.; Lobo, G.; Lopez, G. C.; Lubimov, V.; Lüke, D.; Lytkin, L.; Magnussen, N.; Mahlke-Krüger, H.; Malinovski, E.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, G.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Mavroidis, T.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Merkel, P.; Metlica, F.; Meyer, A.; Meyer, A.; Meyer, H.; Meyer, J.; Meyer, P.-O.; Migliori, A.; Mikocki, S.; Milstead, D.; Moeck, J.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, D.; Müller, K.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Négri, I.; Newman, P. R.; Newton, D.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Niedzballa, Ch.; Niggli, H.; Nowak, G.; Nunnemann, T.; Oberlack, H.; Olsson, J. E.; Ozerov, D.; Palmen, P.; Panaro, E.; Panitch, A.; Pascaud, C.; Passaggio, S.; Patel, G. D.; Pawletta, H.; Peppel, E.; Perez, E.; Phillips, J. P.; Pieuchot, A.; Pitzl, D.; Pöschl, R.; Pope, G.; Povh, B.; Rabbertz, K.; Reimer, P.; Rick, H.; Riess, S.; Rizvi, E.; Robmann, P.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rüter, K.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Schacht, P.; Scheins, J.; Schiek, S.; Schleif, S.; Schleper, P.; von Schlippe, W.; Schmidt, D.; Schmidt, G.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schultz-Coulon, H.-C.; Schwab, B.; Sefkow, F.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Sloan, T.; Smirnov, P.; Smith, M.; Solochenko, V.; Soloviev, Y.; Specka, A.; Spiekermann, J.; Spielman, S.; Spitzer, H.; Squinabol, F.; Steffen, P.; Steinberg, R.; Steinhart, J.; Stella, B.; Stellberger, A.; Stiewe, J.; Stolze, K.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Swart, M.; Tapprogge, S.; Taševský, M.; Tchernyshov, V.; Tchetchelnitski, S.; Theissen, J.; Thompson, G.; Thompson, P. D.; Tobien, N.; Todenhagen, R.; Truöl, P.; Zálešák, J.; Tsipolitis, G.; Turnau, J.; Tzamariudaki, E.; Uelkes, P.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; van Esch, P.; van Mechelen, P.; Vandenplas, D.; Vazdik, Y.; Verrecchia, P.; Villet, G.; Wacker, K.; Wagener, A.; Wagener, M.; Wallny, R.; Walter, T.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; West, L. R.; Wiesand, S.; Wilksen, T.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wobisch, M.; Wollatz, H.; Wünsch, E.; Žáček, J.; Zarbock, D.; Zhang, Z.; Zhokin, A.; Zini, P.; Zomer, F.; Zsembery, J.; Zurnedden, M.

1997-12-01

The transition between photoproduction and deep-inelastic scattering is investigated in jet production at the HERA ep collider, using data collected by the H1 experiment. Measurements of the differential inclusive jet cross-sections dσep/dEt* and dσep/dη*, where Et* and η* are the transverse energy and the pseudorapidity of the jets in the virtual photon-proton centre of mass frame, are presented for 0

Regional primitive equation modeling and analysis of the polymode data set

NASA Astrophysics Data System (ADS)

Spall, Michael A.

A regional, hybrid coordinate, primitive equation (PE) model is applied to a 60-day period of the POLYMODE data set. The initialization techniques and open boundary conditions introduced by Spall and Robinson are shown to produce stable, realistic, and reasonably accurate hindcasts for the 2-month data set. Comparisons with quasi-geostrophic (QG) modeling studies indicate that the PE model reproduced the jet formation that dominates the region more accurately than did the QG model. When the PE model used boundary conditions that were partially adjusted by the QG model, the resulting fields were very similar to the QG fields, indicating a rapid degradation of small-scale features near the boundaries in the QG calculation. A local term-by-term primitive equation energy and vorticity analysis package is also introduced. The full vorticity, horizontal divergence, kinetic energy, and available gravitational energy equations are solved diagnostically from the output of the regional PE model. Through the analysis of a time series of horizontal maps, the dominant processes in the flow are illustrated. The individual terms are also integrated over the region of jet formation to highlight the net balances as a function of time. The formation of the deep thermocline jet is shown to be due to horizontal advection through the boundary, baroclinic conversion in the deep thermocline and vertical pressure work, which exports the deep energy to the upper thermocline levels. It is concluded here that the PE model reproduces the observed jet formation better than the QG model because of the increased horizontal advection and stronger vertical pressure work. Although the PE model is shown to be superior to the QG model in this application, it is believed that both PE and QG models can play an important role in the regional study of mid-ocean mesoscale eddies.

Modelling Oil Droplet Breakup in a Turbulent Jet

NASA Astrophysics Data System (ADS)

Philip, Rachel; Hewitt, Ian; Howell, Peter

2017-11-01

In a deep-sea oil spill, a broken pipe near the seabed can result in the release of a turbulent oil jet into the surrounding ocean. The jet's shearing motion will typically cause the oil to break up into smaller droplets, which are then more readily dispersed and decomposed by sea microbes. In order to understand this natural clean-up process, we develop analytical and numerical models for the drop size distribution at different locations in the jet. This involves examining and unifying disparate scales, from the macroscopic jet to the microscopic droplets. We first examine the turbulent jet and we can use its self-similarity to simplify our models. We then turn to the droplet scale, considering the rate at which drops are deformed and broken up. Droplet deformation is precipitated by the jet's turbulent mixing and shearing and thus depends on the macroscopic jet models. We combine these large and small scale models to determine the droplet size distribution, as it varies with jet location. By varying the initial conditions and parameters in these models, we obtain insights into the factors affecting this droplet breakup process and how it may be optimised.

Infrasound associated with the deep M 7.3 northeastern China earthquake of June 28, 2002

NASA Astrophysics Data System (ADS)

Che, Il-Young; Kim, Geunyoung; Le Pichon, Alexis

2013-02-01

On 28 June, 2002, a deep-focus (566 km) earthquake with a moment magnitude of 7.3 occurred in the China-Russia-North Korea border region. Despite its deep focus, the earthquake produced an infrasound signal that was observed by the remote infrasound array (CHNAR), 682 km from the epicenter, in South Korea. Coherent infrasound signals were detected sequentially at the receiver, with different arrival times and azimuths indicating that the signals were generated both near the epicenter and elsewhere. On the basis of the azimuth, arrival time measurements, and atmospheric ray simulation results, the source area of the infrasonic signals that arrived earlier were located along the eastern coastal areas of North Korea and Russia, whereas later signals were sourced throughout Japan. The geographically-constrained, and discrete, distribution of the sources identified is explained by infrasound propagation effects caused by a westward zonal wind that was active when the event occurred. The amplitude of the deep quake's signal was equivalent to that of a shallow earthquake with a magnitude of approximately 5. This study expands the breadth of seismically-associated infrasound to include deep earthquakes, and also supports the possibility that infrasound measurements could help determine the depth of earthquakes.

Historical and projected changes in the Southern Hemisphere Sub-tropical Jet during winter from the CMIP5 models

NASA Astrophysics Data System (ADS)

Chenoli, Sheeba Nettukandy; Ahmad Mazuki, Muhammad Yunus; Turner, John; Samah, Azizan Abu

2017-01-01

We present projected changes in the speed and meridional location of the Subtropical Jet (STJ) during winter using output of the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. We use the ERA-Interim reanalysis dataset to evaluate the historical simulations of the STJ by 18 of the CMIP5 models for the period 1979-2012. Based on the climatology of the STJ from ERA-Interim, we selected the area of study as 70°E-290°E and 20°S-40°S, which is over the Indian and Southern Pacific Oceans, and 300-100 hPa to reduce altitude-related bias. An assessment of the ability of the CMIP5 models in simulating ENSO effects on the jet stream were carried out using standardized zonal wind anomalies at 300-100 hPa. Results show that 47 % of the CMIP5 models used in this study were able to simulate ENSO impacts realistically. In addition, it is more difficult for the models to reproduce the observed intensity of ENSO impacts than the patterns. The historical simulations of the CMIP5 models show a wide range of trends in meridional movement and jet strength, with a multi-model mean of 0.04° decade-1 equatorward and 0.42 ms-1 decade-1 respectively. In contrast to the ERA-Interim analysis, 94 % of the CMIP5 models show a strengthening of the jet in the historical runs. Variability of the jet strength is significantly (5 %) linked to the sea surface temperature changes over the eastern tropical Pacific. The CMIP5 model projections with Representative Concentration Pathways (RCPs) 4.5 and 8.5 were used for analysis of changes of the STJ for the period 2011-2099. Based on the RCP 4.5 (RCP 8.5) scenario the multi-model mean trend of the 18 CMIP5 models project a statistically significant (5 % level) increase in jet strength by the end of the century of 0.29 ms-1 decade-1 (0.60 ms-1 decade-1). Also, the mean meridional location of the jet is projected to shift poleward by 0.006° decade-1 (0.042° decade-1) in 2099 during winter, with the only significant (5 %) trend being with RCP 8.5.

A suppression of differential rotation in Jupiter’s deep interior

NASA Astrophysics Data System (ADS)

Guillot, T.; Miguel, Y.; Militzer, B.; Hubbard, W. B.; Kaspi, Y.; Galanti, E.; Cao, H.; Helled, R.; Wahl, S. M.; Iess, L.; Folkner, W. M.; Stevenson, D. J.; Lunine, J. I.; Reese, D. R.; Biekman, A.; Parisi, M.; Durante, D.; Connerney, J. E. P.; Levin, S. M.; Bolton, S. J.

2018-03-01

Jupiter’s atmosphere is rotating differentially, with zones and belts rotating at speeds that differ by up to 100 metres per second. Whether this is also true of the gas giant’s interior has been unknown, limiting our ability to probe the structure and composition of the planet. The discovery by the Juno spacecraft that Jupiter’s gravity field is north–south asymmetric and the determination of its non-zero odd gravitational harmonics J3, J5, J7 and J9 demonstrates that the observed zonal cloud flow must persist to a depth of about 3,000 kilometres from the cloud tops. Here we report an analysis of Jupiter’s even gravitational harmonics J4, J6, J8 and J10 as observed by Juno and compared to the predictions of interior models. We find that the deep interior of the planet rotates nearly as a rigid body, with differential rotation decreasing by at least an order of magnitude compared to the atmosphere. Moreover, we find that the atmospheric zonal flow extends to more than 2,000 kilometres and to less than 3,500 kilometres, making it fully consistent with the constraints obtained independently from the odd gravitational harmonics. This depth corresponds to the point at which the electric conductivity becomes large and magnetic drag should suppress differential rotation. Given that electric conductivity is dependent on planetary mass, we expect the outer, differentially rotating region to be at least three times deeper in Saturn and to be shallower in massive giant planets and brown dwarfs.

The interactive role of subsynoptic scale jet sreak and planetary boundary layer adjustments in organizing an apparently isolated convective complex

NASA Technical Reports Server (NTRS)

Kaplan, M. L.; Zack, J. W.; Wong, V. C.; Tuccillo, J. J.; Coats, G. D.

1982-01-01

A mesoscale atmospheric simulation system is described that is being developed in order to improve the simulation of subsynoptic and mesoscale adjustments associated with cyclogenesis, severe storm development, and significant atmospheric transport processes. Present emphasis in model development is in the parameterization of physical processes, time-dependent boundary conditions, sophisticated initialization and analysis procedures, nested grid solutions, and applications software development. Basic characteristics of the system as of March 1982 are listed. In a case study, the Grand Island tornado outbreak of 3 June 1980 is considered in substantial detail. Results of simulations with a mesoscale atmospheric simulation system indicate that over the high plains subtle interactions between existing jet streaks and deep well mixed boundary layers can lead to well organized patterns of mesoscale divergence and pressure falls. The amplitude and positioning of these mesoscale features is a function of the subtle nonlinear interaction between the pre-existing jet-streak and deep well mixed boundary layers. Model results for the case study indicate that the model has the potential for forecasting the precursor mesoscale convective environment.

Quark fragmentation functions in NJL-jet model

NASA Astrophysics Data System (ADS)

Bentz, Wolfgang; Matevosyan, Hrayr; Thomas, Anthony

2014-09-01

We report on our studies of quark fragmentation functions in the Nambu-Jona-Lasinio (NJL) - jet model. The results of Monte-Carlo simulations for the fragmentation functions to mesons and nucleons, as well as to pion and kaon pairs (dihadron fragmentation functions) are presented. The important role of intermediate vector meson resonances for those semi-inclusive deep inelastic production processes is emphasized. Our studies are very relevant for the extraction of transverse momentum dependent quark distribution functions from measured scattering cross sections. We report on our studies of quark fragmentation functions in the Nambu-Jona-Lasinio (NJL) - jet model. The results of Monte-Carlo simulations for the fragmentation functions to mesons and nucleons, as well as to pion and kaon pairs (dihadron fragmentation functions) are presented. The important role of intermediate vector meson resonances for those semi-inclusive deep inelastic production processes is emphasized. Our studies are very relevant for the extraction of transverse momentum dependent quark distribution functions from measured scattering cross sections. Supported by Grant in Aid for Scientific Research, Japanese Ministry of Education, Culture, Sports, Science and Technology, Project No. 20168769.

N3LO corrections to jet production in deep inelastic scattering using the Projection-to-Born method

NASA Astrophysics Data System (ADS)

Currie, J.; Gehrmann, T.; Glover, E. W. N.; Huss, A.; Niehues, J.; Vogt, A.

2018-05-01

Computations of higher-order QCD corrections for processes with exclusive final states require a subtraction method for real-radiation contributions. We present the first-ever generalisation of a subtraction method for third-order (N3LO) QCD corrections. The Projection-to-Born method is used to combine inclusive N3LO coefficient functions with an exclusive second-order (NNLO) calculation for a final state with an extra jet. The input requirements, advantages, and potential applications of the method are discussed, and validations at lower orders are performed. As a test case, we compute the N3LO corrections to kinematical distributions and production rates for single-jet production in deep inelastic scattering in the laboratory frame, and compare them with data from the ZEUS experiment at HERA. The corrections are small in the central rapidity region, where they stabilize the predictions to sub per-cent level. The corrections increase substantially towards forward rapidity where large logarithmic effects are expected, thereby yielding an improved description of the data in this region.

The research of breaking rock with liquid-solid two-phase jet flow

NASA Astrophysics Data System (ADS)

Cheng, X. Z.; Ren, F. S.; Fang, T. C.

2018-03-01

Abstracts. Particle impact drilling is an efficient way of breaking rock, which is mainly used in deep drilling and ultra-deep drilling. The differential equation was established based on the theory of Hertz and Newton’s second law, through the analysis of particle impact rock, the depth of particles into the rock was obtained. The mathematical model was established based on the effect of water impact crack. The research results show when water jet speed is more than 40 m/s, rock stability coefficient is more than 1.0, the rock fracture appear. Through the experimental research of particle impact drilling facilities, analysis of cuttings and the crack size which was analyzed through Scanning electron microscope consistent with the theoretical calculation, the validity of the model was verified.

Jet dynamics post drop impact on a deep pool

NASA Astrophysics Data System (ADS)

Michon, Guy-Jean; Josserand, Christophe; Séon, Thomas

2017-02-01

We investigate experimentally the jet formed by the collapse of a cavity created by the impact of a drop on a pool of the same aqueous liquid. We show that jets can emerge with very different shapes and velocities, depending on the impact parameters, thus generating droplets with various initial sizes and velocities. After presenting the jet velocity and top drop radius variation as a function of the impact parameters, we discuss the influence of the liquid parameters on the jet velocity. This allows us to define two different regimes: the singular jet and the cavity jet regimes, where the mechanisms leading to the cavity retraction and subsequent jet dynamics are drastically different. In particular, we demonstrate that in the first regime, a singular capillary wave collapse sparks the whole jet dynamics, making the jet's fast, thin, liquid parameters dependent and barely reproducible. On the contrary, in the cavity jet regime, defined for higher impact Froude numbers, the jets are fat and slow. We show that jet velocity is simply proportional to the capillary velocity √{γ /ρlDd }, where γ is the liquid surface tension, ρl the liquid density, and Dd the impacting drop diameter, and it is in particular independent of viscosity, impact velocity, and gravity, even though the cavity is larger than the capillary length. Finally, we demonstrate that capillary wave collapse and cavity retraction are correlated in the singular regime and decorrelated in the cavity jet regime.

Anomalous high-frequency wave activity flux preceding anomalous changes in the Northern polar jet

NASA Astrophysics Data System (ADS)

Nakamura, Mototaka; Kadota, Minoru; Yamane, Shozo

2010-05-01

Anomalous forcing by quasi-geostrophic (QG) waves has been reported as an important forcing factor in the Northern Annular Mode (NAM) in recent literatures. In order to shed a light on the dynamics of the NAM from a different angle, we have examined anomalous behavior of the winter jets in the upper troposphere and stratosphere by focusing our diagnosis on not the anomalous geopotential height (Z) itself, but on the anomalous change in the Z (dZ) between two successive months and preceding transient QG wave activity flux during the cold season. We calculated EOFs of dZ between two successive months at 150hPa for a 46-year period, from 1958 to 2003, using the monthly mean NCEP reanalysis data. We then formed anomaly composites of changes in Z and the zonal velocity (U), as well as the preceding and following wave activity flux, Z, U, and temperature at various heights, for both positive and negative phases of the first EOF. For the wave forcing fields, we adopted the diagnostic system for the three-dimensional QG transient wave activity flux in the zonally-varying three-dimensional mean flow developed by Plumb (1986) with a slight modification in its application to the data. Our choice of the Plumb86 is based on the fact that the winter mean flow in the Northern Hemisphere is characterized by noticeable zonal asymmetry, and has a symbiotic relationship with waves in the extra-tropics. The Plumb86 flux was calculated for high-frequency (period of 2 to 7 days) and low-frequency (period of 10 to 20 days) waves with the ultra-low-frequency (period of 30 days or longer) flow as the reference state for each time frame of the 6 hourly NCEP reanalysis data from 1958 to 2003. By replacing the mean flow with the ultra-low-frequency flow in the application of the Plumb86 formula, the flux fields were calculated as time series at 6 hour intervals. The time series of the wave activity flux was then averaged for each month. The patterns of composited anomalous dZ and dU clearly show anomalous acceleration or deceleration of U in the polar region, accompanied by anomalies of the opposite sign in the subtropics throughout the troposphere and stratosphere. The anomalies are conspicuously large in the polar stratosphere. The composited anomalous Z and U in the preceding and following months indicate that these large anomalies in dZ and dU occur when the polar troposphere and stratosphere are relaxing back toward the climatology from strongly anomalous states that closely resemble the positive and negative phases of the NAM. In this process of relaxation, the atmosphere actually overshoots the climatology and develops anomalies of the sign opposite to those existed initially. The anomalous wave activity flux exhibit strong signals of anomalous upward (downward) propagation of high-frequency waves in the North Atlantic storm track from the bottom of the atmosphere, penetrating up to the stratosphere, when the polar jet is anomalously strong (weak) in the preceding month. The anomalous horizontal wave activity flux shows anomalous eastward (westward) flux emanating from the North Atlantic storm track when the polar jet is anomalously strong (weak) in the preceding month. These patterns suggest that anomalous high-frequency waves originating from the North Atlantic storm track in the lower troposphere contribute to the destruction of both phases of the NAM. However, the anomalous flux divergence is very noisy everywhere due to the noisiness of the advective horizontal flux, making it difficult to ascertain the role of the high-frequency transients in the destruction of the NAM.

Impressions from Cassini

NASA Technical Reports Server (NTRS)

2005-01-01

Saturn's turbulent atmosphere is reminiscent of a Van Gogh painting in this view from Cassini. However, unlike the famous impressionist painter, Cassini records the world precisely as it appears to the spacecraft's cameras.

The feathery band that cuts across from the upper left corner to the right side of this scene has a chevron, or arrow, shape near the right. The center of the chevron is located at the latitude (about 28 degrees South) of an eastward-flowing zonal jet in the atmosphere. Counter-flowing eastward and westward jets are the dominant dynamic features seen in the giant planet atmospheres. A chevron-shaped feature with the tip pointed east means that this is a local maximum in the eastward wind and a region of horizontal wind shear, where clouds to the north and south of the jet are being swept back by the slower currents on the sides of the jet.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 6, 2005, at a distance of approximately 2.5 million kilometers (1.5 million miles) from Saturn using a filter sensitive to wavelengths of infrared light centered at 727 nanometers. The image scale is 14 kilometers (9 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Impact factor for high-energy two and three jets diffractive production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boussarie, R.; Grabovsky, A.V.; Szymanowski, L.

2015-04-10

We present the calculation of the impact factor for the photon to quark, antiquark and gluon transition within Balitsky’s shock-wave formalism. We also rederive the impact factor for photon to quark and antiquark transition. These results provide the necessary building blocks for further phenomenological studies of inclusive diffractive deep inelastic scattering as well as for two and three jets diffractive production which go beyond approximations discussed in the literature.

Global climate impacts of stochastic deep convection parameterization in the NCAR CAM5

DOE PAGES

Wang, Yong; Zhang, Guang J.

2016-09-29

In this paper, the stochastic deep convection parameterization of Plant and Craig (PC) is implemented in the Community Atmospheric Model version 5 (CAM5) to incorporate the stochastic processes of convection into the Zhang-McFarlane (ZM) deterministic deep convective scheme. Its impacts on deep convection, shallow convection, large-scale precipitation and associated dynamic and thermodynamic fields are investigated. Results show that with the introduction of the PC stochastic parameterization, deep convection is decreased while shallow convection is enhanced. The decrease in deep convection is mainly caused by the stochastic process and the spatial averaging of input quantities for the PC scheme. More detrainedmore » liquid water associated with more shallow convection leads to significant increase in liquid water and ice water paths, which increases large-scale precipitation in tropical regions. Specific humidity, relative humidity, zonal wind in the tropics, and precipitable water are all improved. The simulation of shortwave cloud forcing (SWCF) is also improved. The PC stochastic parameterization decreases the global mean SWCF from -52.25 W/m 2 in the standard CAM5 to -48.86 W/m 2, close to -47.16 W/m 2 in observations. The improvement in SWCF over the tropics is due to decreased low cloud fraction simulated by the stochastic scheme. Sensitivity tests of tuning parameters are also performed to investigate the sensitivity of simulated climatology to uncertain parameters in the stochastic deep convection scheme.« less

Global climate impacts of stochastic deep convection parameterization in the NCAR CAM5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yong; Zhang, Guang J.

In this paper, the stochastic deep convection parameterization of Plant and Craig (PC) is implemented in the Community Atmospheric Model version 5 (CAM5) to incorporate the stochastic processes of convection into the Zhang-McFarlane (ZM) deterministic deep convective scheme. Its impacts on deep convection, shallow convection, large-scale precipitation and associated dynamic and thermodynamic fields are investigated. Results show that with the introduction of the PC stochastic parameterization, deep convection is decreased while shallow convection is enhanced. The decrease in deep convection is mainly caused by the stochastic process and the spatial averaging of input quantities for the PC scheme. More detrainedmore » liquid water associated with more shallow convection leads to significant increase in liquid water and ice water paths, which increases large-scale precipitation in tropical regions. Specific humidity, relative humidity, zonal wind in the tropics, and precipitable water are all improved. The simulation of shortwave cloud forcing (SWCF) is also improved. The PC stochastic parameterization decreases the global mean SWCF from -52.25 W/m 2 in the standard CAM5 to -48.86 W/m 2, close to -47.16 W/m 2 in observations. The improvement in SWCF over the tropics is due to decreased low cloud fraction simulated by the stochastic scheme. Sensitivity tests of tuning parameters are also performed to investigate the sensitivity of simulated climatology to uncertain parameters in the stochastic deep convection scheme.« less

The gas jet behavior in submerged Laval nozzle flow

NASA Astrophysics Data System (ADS)

Gong, Zhao-xin; Lu, Chuan-jing; Li, Jie; Cao, Jia-yi

2017-12-01

The behavior of the combustion gas jet in a Laval nozzle flow is studied by numerical simulations. The Laval nozzle is installed in an engine and the combustion gas comes out of the engine through the nozzle and then injects into the surrounding environment. First, the jet injection into the air is simulated and the results are verified by the theoretical solutions of the 1-D isentropic flow. Then the behavior of the gas jet in a submerged Laval nozzle flow is simulated for various water depths. The stability of the jet and the jet evolution with a series of expansion waves and compression waves are analyzed, as well as the mechanism of the jet in a deep water depth. Finally, the numerical results are compared with existing experimental data and it is shown that the characteristics of the water blockage and the average values of the engine thrust are in good agreement and the unfixed engine in the experiment is the cause of the differences of the frequency and the amplitude of the oscillation.

Pronounced zonal heterogeneity in Eocene southern high-latitude sea surface temperatures.

PubMed

Douglas, Peter M J; Affek, Hagit P; Ivany, Linda C; Houben, Alexander J P; Sijp, Willem P; Sluijs, Appy; Schouten, Stefan; Pagani, Mark

2014-05-06

Paleoclimate studies suggest that increased global warmth during the Eocene epoch was greatly amplified at high latitudes, a state that climate models cannot fully reproduce. However, proxy estimates of Eocene near-Antarctic sea surface temperatures (SSTs) have produced widely divergent results at similar latitudes, with SSTs above 20 °C in the southwest Pacific contrasting with SSTs between 5 and 15 °C in the South Atlantic. Validation of this zonal temperature difference has been impeded by uncertainties inherent to the individual paleotemperature proxies applied at these sites. Here, we present multiproxy data from Seymour Island, near the Antarctic Peninsula, that provides well-constrained evidence for annual SSTs of 10-17 °C (1σ SD) during the middle and late Eocene. Comparison of the same paleotemperature proxy at Seymour Island and at the East Tasman Plateau indicate the presence of a large and consistent middle-to-late Eocene SST gradient of ∼7 °C between these two sites located at similar paleolatitudes. Intermediate-complexity climate model simulations suggest that enhanced oceanic heat transport in the South Pacific, driven by deep-water formation in the Ross Sea, was largely responsible for the observed SST gradient. These results indicate that very warm SSTs, in excess of 18 °C, did not extend uniformly across the Eocene southern high latitudes, and suggest that thermohaline circulation may partially control the distribution of high-latitude ocean temperatures in greenhouse climates. The pronounced zonal SST heterogeneity evident in the Eocene cautions against inferring past meridional temperature gradients using spatially limited data within given latitudinal bands.

Pronounced zonal heterogeneity in Eocene southern high-latitude sea surface temperatures

PubMed Central

Douglas, Peter M. J.; Affek, Hagit P.; Ivany, Linda C.; Houben, Alexander J. P.; Sijp, Willem P.; Sluijs, Appy; Schouten, Stefan; Pagani, Mark

2014-01-01

Paleoclimate studies suggest that increased global warmth during the Eocene epoch was greatly amplified at high latitudes, a state that climate models cannot fully reproduce. However, proxy estimates of Eocene near-Antarctic sea surface temperatures (SSTs) have produced widely divergent results at similar latitudes, with SSTs above 20 °C in the southwest Pacific contrasting with SSTs between 5 and 15 °C in the South Atlantic. Validation of this zonal temperature difference has been impeded by uncertainties inherent to the individual paleotemperature proxies applied at these sites. Here, we present multiproxy data from Seymour Island, near the Antarctic Peninsula, that provides well-constrained evidence for annual SSTs of 10–17 °C (1σ SD) during the middle and late Eocene. Comparison of the same paleotemperature proxy at Seymour Island and at the East Tasman Plateau indicate the presence of a large and consistent middle-to-late Eocene SST gradient of ∼7 °C between these two sites located at similar paleolatitudes. Intermediate-complexity climate model simulations suggest that enhanced oceanic heat transport in the South Pacific, driven by deep-water formation in the Ross Sea, was largely responsible for the observed SST gradient. These results indicate that very warm SSTs, in excess of 18 °C, did not extend uniformly across the Eocene southern high latitudes, and suggest that thermohaline circulation may partially control the distribution of high-latitude ocean temperatures in greenhouse climates. The pronounced zonal SST heterogeneity evident in the Eocene cautions against inferring past meridional temperature gradients using spatially limited data within given latitudinal bands. PMID:24753570

A ray tracing model of gravity wave propagation and breakdown in the middle atmosphere

NASA Technical Reports Server (NTRS)

Schoeberl, M. R.

1985-01-01

Gravity wave ray tracing and wave packet theory is used to parameterize wave breaking in the mesosphere. Rays are tracked by solving the group velocity equations, and the interaction with the basic state is determined by considering the evolution of the packet wave action density. The ray tracing approach has a number of advantages over the steady state parameterization as the effects of gravity wave focussing and refraction, local dissipation, and wave response to rapid changes in the mean flow are more realistically considered; however, if steady state conditions prevail, the method gives identical results. The ray tracing algorithm is tested using both interactive and noninteractive models of the basic state. In the interactive model, gravity wave interaction with the polar night jet on a beta-plane is considered. The algorithm produces realistic polar night jet closure for weak topographic forcing of gravity waves. Planetary scale waves forced by local transfer of wave action into the basic flow in turn transfer their wave action into the zonal mean flow. Highly refracted rays are also found not to contribute greatly to the climatology of the mesosphere, as their wave action is severely reduced by dissipation during their lateral travel.

Generation of zonal flows through symmetry breaking of statistical homogeneity

NASA Astrophysics Data System (ADS)

Parker, Jeffrey B.; Krommes, John A.

2014-03-01

In geophysical and plasma contexts, zonal flows (ZFs) are well known to arise out of turbulence. We elucidate the transition from homogeneous turbulence without ZFs to inhomogeneous turbulence with steady ZFs. Starting from the equation for barotropic flow on a β plane, we employ both the quasilinear approximation and a statistical average, which retains a great deal of the qualitative behavior of the full system. Within the resulting framework known as CE2, we extend recent understanding of the symmetry-breaking zonostrophic instability and show that it is an example of a Type {{\\text{I}}_{s}} instability within the pattern formation literature. The broken symmetry is statistical homogeneity. Near the bifurcation point, the slow dynamics of CE2 are governed by a well-known amplitude equation. The important features of this amplitude equation, and therefore of the CE2 system, are multiple. First, the ZF wavelength is not unique. In an idealized, infinite system, there is a continuous band of ZF wavelengths that allow a nonlinear equilibrium. Second, of these wavelengths, only those within a smaller subband are stable. Unstable wavelengths must evolve to reach a stable wavelength; this process manifests as merging jets. These behaviors are shown numerically to hold in the CE2 system. We also conclude that the stability of the equilibria near the bifurcation point, which is governed by the Eckhaus instability, is independent of the Rayleigh-Kuo criterion.

First absolute wind measurements in the middle atmosphere of Mars

NASA Astrophysics Data System (ADS)

Lellouch, Emmanuel; Goldstein, Jeffrey J.; Bougher, Stephen W.; Paubert, Gabriel; Rosenqvist, Jan

1991-12-01

The first absolute wind measurements in the middle atmosphere of Mars (40-70 km) were obtained from Doppler shifts in the J = 2-1 CO transition at 230.538 GHz. During the 1988 opposition, this line was observed at 100 kHz resolution with the IRAM 30 m telescope. The 12-arcsec FWHM beam of the facility allowed spatial resolution of the Martian disk (23.8 arcsec). The high S/N of the data allowed measurement of winds with a 1-sigma absolute line-of-sight accuracy of 20 m/s. The measurements, performed during southern summer solstice, stress the Southern Hemisphere and clearly indicate a global easterlies flow. If modeled by a broad easterly jet with a maximum centered at 20 S, and extending 80 deg in latitude, the jet core velocity is found to have a chi-sq minimum at 160 m/s, generally consistent with predictions for broad summer easterly jets near 50 km as proposed by theoretical models. If the flow is modeled instead by a planet-wide solid rotator zonal flow which is restricted to the Southern Hemisphere or equatorial regions, the velocity of the easterlies is nearly the same. These wind measurements, together with the temperature measurements of Deming et al. (1986), provide the first experimental rough picture of the middle atmosphere circulation of Mars, in general agreement with the Jaquin axisymmetric middle atmosphere model and the current Mars GCM model of Pollack et al. (1990).

Meso-beta scale numerical simulation studies of terrain-induced jet streak mass/momentum perturbations

NASA Technical Reports Server (NTRS)

Lin, Yuh-Lang; Kaplan, Michael L.

1995-01-01

Mesoscale model simulations provide insight into the complex jet streak adjustments on 11-12 July 1981 that preceded the first of two significant gravity wave events to have been generated over the Rocky Mountains in Montana. Simulations employing a variety of terrain treatments indicate that prior to wave formation, geostrophic adjustment processes modified the structure of the mid-upper tropospheric jet streak by creating secondary jetlets to the southeast of the polar jet streak in proximity to the gravity wave generation region. This simulated restructuring of the mid-upper tropospheric jet streak is the result of a four stage process. During stage 1, the wind adjusts to the mass field as the jet streak exit region propagates into the inflection point between the upstream trough and downstream ridge in the height field. Stage 2 is initiated as the mass field is forced to adjust to the new ageostrophic wind field created during stage 1. Stage 3 is defined by a second geostrophic adjustment process occurring in a similar manner but to the south and east of the adjustment which occurs during stage 1. A low-level mesoscale jetlet is formed during stage 4 in response to the low-level pressure falls that are established during stage 3. The perturbation of this jetlet, caused by orographically-induced adiabatic and diabatic physical processes, is the likely mechanism responsible for the generation of the first and second episode of observed gravity waves. The dynamics responsible for this wave episode are discussed as differential surface sensible heating inducing an orographically-forced mountain-plains solenoid, resulting in the formation of additional mesoscale jetlets and internal gravity waves. Also discussed is how convective latent heating modifies the numerically simulated terrain-induced internal gravity waves, especially their amplitude and phase velocities, which provide better agreement with those wave characteristics observed in nature. Finally, the three-dimensional linear response of a zonally uniform barotropic flow in a vertically unbounded, continuously stratified, Boussinesq atmosphere which is perturbed from geostrophic equilibrium is investigated.

A Non-hydrostatic Atmospheric Model for Global High-resolution Simulation

NASA Astrophysics Data System (ADS)

Peng, X.; Li, X.

2017-12-01

A three-dimensional non-hydrostatic atmosphere model, GRAPES_YY, is developed on the spherical Yin-Yang grid system in order to enforce global high-resolution weather simulation or forecasting at the CAMS/CMA. The quasi-uniform grid makes the computation be of high efficiency and free of pole problem. Full representation of the three-dimensional Coriolis force is considered in the governing equations. Under the constraint of third-order boundary interpolation, the model is integrated with the semi-implicit semi-Lagrangian method using the same code on both zones. A static halo region is set to ensure computation of cross-boundary transport and updating Dirichlet-type boundary conditions in the solution process of elliptical equations with the Schwarz method. A series of dynamical test cases, including the solid-body advection, the balanced geostrophic flow, zonal flow over an isolated mountain, development of the Rossby-Haurwitz wave and a baroclinic wave, are carried out, and excellent computational stability and accuracy of the dynamic core has been confirmed. After implementation of the physical processes of long and short-wave radiation, cumulus convection, micro-physical transformation of water substances and the turbulent processes in the planetary boundary layer include surface layer vertical fluxes parameterization, a long-term run of the model is then put forward under an idealized aqua-planet configuration to test the model physics and model ability in both short-term and long-term integrations. In the aqua-planet experiment, the model shows an Earth-like structure of circulation. The time-zonal mean temperature, wind components and humidity illustrate reasonable subtropical zonal westerly jet, meridional three-cell circulation, tropical convection and thermodynamic structures. The specific SST and solar insolation being symmetric about the equator enhance the ITCZ and tropical precipitation, which concentrated in tropical region. Additional analysis and tuning of the model is still going on, and preliminary results have demonstrated the possibility of high-resolution application of the model to global weather prediction and even seasonal climate projection.

Gulf Coast Deep Water Port Facilities Study. Appendix C. Eastern Gulf Hydrobiological Zones.

DTIC Science & Technology

1973-04-01

MARINE 5IOTA C-22 1. Benthic Plants C-22 2. Plankton C;23 3. Benthic Invertebrates C-27 4. Fish C-33 5. Marine Mammals C-35 6. Marine Birds C-37 7. Rare...56 B. RESIDENT AND TRANSIENT MARINE BIOTA C-56 1. Plankton C-56 2. Benthic Invertebrates C-62 3. Fish C-62 4. Marine Mammals C-684 Artur D Little Inc...TRANSIENT MARINE BIOTA C-78 l.-Plankton C-78 .-2. Benthic Invertebrates C8 3. F ish C-81 4. Marine Mammals C-85 V. ZONAL ANALYSIS C-87 A. ZONE V

A Robust Response of the Hadley Circulation to Global Warming

NASA Technical Reports Server (NTRS)

Lau, William K M.; Kim, Kyu-Myong

2014-01-01

Tropical rainfall is expected to increase in a warmer climate. Yet, recent studies have inferred that the Hadley Circulation (HC), which is primarily driven by latent heating from tropical rainfall, is weakened under global warming. Here, we show evidence of a robust intensification of the HC from analyses of 33 CMIP5 model projections under a scenario of 1 per year CO2 emission increase. The intensification is manifested in a deep-tropics squeeze, characterized by a pronounced increase in the zonal mean ascending motion in the mid and upper troposphere, a deepening and narrowing of the convective zone and enhanced rainfall in the deep tropics. These changes occur in conjunction with a rise in the region of maximum outflow of the HC, with accelerated meridional mass outflow in the uppermost branch of the HC away from the equator, coupled to a weakened inflow in the return branches of the HC in the lower troposphere.

Deep Chandra observations of Pictor A

NASA Astrophysics Data System (ADS)

Hardcastle, M. J.; Lenc, E.; Birkinshaw, M.; Croston, J. H.; Goodger, J. L.; Marshall, H. L.; Perlman, E. S.; Siemiginowska, A.; Stawarz, Ł.; Worrall, D. M.

2016-02-01

We report on deep Chandra observations of the nearby broad-line radio galaxy Pictor A, which we combine with new Australia Telescope Compact Array (ATCA) observations. The new X-ray data have a factor of 4 more exposure than observations previously presented and span a 15 yr time baseline, allowing a detailed study of the spatial, temporal and spectral properties of the AGN, jet, hotspot and lobes. We present evidence for further time variation of the jet, though the flare that we reported in previous work remains the most significantly detected time-varying feature. We also confirm previous tentative evidence for a faint counterjet. Based on the radio through X-ray spectrum of the jet and its detailed spatial structure, and on the properties of the counterjet, we argue that inverse-Compton models can be conclusively rejected, and propose that the X-ray emission from the jet is synchrotron emission from particles accelerated in the boundary layer of a relativistic jet. For the first time, we find evidence that the bright western hotspot is also time-varying in X-rays, and we connect this to the small-scale structure in the hotspot seen in high-resolution radio observations. The new data allow us to confirm that the spectrum of the lobes is in good agreement with the predictions of an inverse-Compton model and we show that the data favour models in which the filaments seen in the radio images are predominantly the result of spatial variation of magnetic fields in the presence of a relatively uniform electron distribution.

Predawn plasma bubble cluster observed in Southeast Asia

NASA Astrophysics Data System (ADS)

Watthanasangmechai, Kornyanat; Yamamoto, Mamoru; Saito, Akinori; Tsunoda, Roland; Yokoyama, Tatsuhiro; Supnithi, Pornchai; Ishii, Mamoru; Yatini, Clara

2016-06-01

Predawn plasma bubble was detected as deep plasma depletion by GNU Radio Beacon Receiver (GRBR) network and in situ measurement onboard Defense Meteorological Satellite Program F15 (DMSPF15) satellite and was confirmed by sparse GPS network in Southeast Asia. In addition to the deep depletion, the GPS network revealed the coexisting submesoscale irregularities. A deep depletion is regarded as a primary bubble. Submesoscale irregularities are regarded as secondary bubbles. Primary bubble and secondary bubbles appeared together as a cluster with zonal wavelength of 50 km. An altitude of secondary bubbles happened to be lower than that of the primary bubble in the same cluster. The observed pattern of plasma bubble cluster is consistent with the simulation result of the recent high-resolution bubble (HIRB) model. This event is only a single event out of 76 satellite passes at nighttime during 3-25 March 2012 that significantly shows plasma depletion at plasma bubble wall. The inside structure of the primary bubble was clearly revealed from the in situ density data of DMSPF15 satellite and the ground-based GRBR total electron content.

The 300 Kpc Long X-Ray Jet in PKS 1127-145, Z=1.18 Quasar: Constraining X-Ray Emission Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siemiginowska, Aneta; /Harvard-Smithsonian Ctr. Astrophys.; Stawarz, Lukasz

2006-11-20

We present a {approx} 100 ksec Chandra X-ray observation and new VLA radio data of the large scale, 300 kpc long X-ray jet in PKS 1127-145, a radio loud quasar at redshift z=1.18. With this deep X-ray observation we now clearly discern the complex X-ray jet morphology and see substructure within the knots. The X-ray and radio jet intensity profiles are seen to be strikingly different with the radio emission peaking strongly at the two outer knots while the X-ray emission is strongest in the inner jet region. The jet X-ray surface brightness gradually decreases by an order of magnitudemore » going out from the core. The new X-ray data contain sufficient counts to do spectral analysis of the key jet features. The X-ray energy index of the inner jet is relatively flat with {alpha}{sub x} = 0.66 {+-} 0.15 and steep in the outer jet with {alpha}{sub x} = 1.0 {+-} 0.2. We discuss the constraints implied by the new data on the X-ray emission models and conclude that ''one-zone'' models fail and at least a two component model is needed to explain the jet's broad-band emission. We propose that the X-ray emission originates in the jet proper while the bulk of the radio emission comes from a surrounding jet sheath. We also consider intermittent jet activity as a possible cause of the observed jet morphology.« less

The deep space 1 encounter with comet 19P/Borrelly

USGS Publications Warehouse

Boice, D.C.; Soderblom, L.A.; Britt, D.T.; Brown, R.H.; Sandel, B.R.; Yelle, R.V.; Buratti, B.J.; Hicks, M.D.; Nelson, R.M.; Rayman, M.D.; Oberst, J.; Thomas, N.

2002-01-01

NASA's Deep Space 1 (DS1) spacecraft successfully encountered comet 19P/Borrelly near perihelion and the Miniature Integrated Camera and Spectrometer (MICAS) imaging system onboard DS1 returned the first high-resolution images of a Jupiter-family comet nucleus and surrounding environment. The images span solar phase angles from 88?? to 52??, providing stereoscopic coverage of the dust coma and nucleus. Numerous surface features are revealed on the 8-km long nucleus in the highest resolution images (47-58 m/pixel). A smooth, broad basin containing brighter regions and mesa-like structures is present in the central part of the nucleus that seems to be the source of jet-like dust features seen in the coma. High ridges seen along the jagged terminator lead to rugged terrain on both ends of the nucleus containing dark patches and smaller series of parallel grooves. No evidence of impact craters with diameters larger than about 200-m are present, indicating a young and active surface. The nucleus is very dark with albedo variations from 0.007 to 0.035. Short-wavelength, infrared spectra from 1.3 to 2.6 ??m revealed a hot, dry surface consistent with less than about 10% actively sublimating. Two types of dust features are seen: Broad fans and highly collimated "jets" in the sunward hemisphere that can be traced to the surface. The source region of the main jet feature, which resolved into at least three smaller "jets" near the surface, is consistent with an area around the rotation pole that is constantly illuminated by the sun during the encounter. Within a few nuclear radii, entrained dust is rapidly accelerated and fragmented and geometrical effects caused from extended source regions are present, as evidenced in radial intensity profiles centered on the jet features that show an increase in source strength with increasing cometocentric distance. Asymmetries in the dust from dayside to nightside are pronounced and may show evidence of lateral flow transporting dust to structures observed in the nightside coma. A summary of the initial results of the Deep Space 1 Mission is provided, highlighting the new knowledge that has been gained thus far.

Monitor and Control of the Deep-Space network via Secure Web

NASA Technical Reports Server (NTRS)

Lamarra, N.

1997-01-01

(view graph) NASA lead center for robotic space exploration. Operating division of Caltech/Jet Propulsion Laboratory. Current missions, Voyagers, Galileo, Pathfinder, Global Surveyor. Upcoming missions, Cassini, Mars and New Millennium.

Measurement of event shape variables in deep inelastic e p scattering

NASA Astrophysics Data System (ADS)

Adloff, C.; Aid, S.; Anderson, M.; Andreev, V.; Andrieu, B.; Arkadov, V.; Arndt, C.; Ayyaz, I.; Babaev, A.; Bähr, J.; Bán, J.; Baranov, P.; Barrelet, E.; Barschke, R.; Bartel, W.; Bassler, U.; Beck, H. P.; Beck, M.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bernardi, G.; Bertrand-Coremans, G.; Beyer, R.; Biddulph, P.; Bizot, J. C.; Borras, K.; Botterweck, F.; Boudry, V.; Bourov, S.; Braemer, A.; Braunschweig, W.; Brisson, V.; Brown, D. P.; Brückner, W.; Bruel, P.; Bruncko, D.; Brune, C.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Calvet, D.; Campbell, A. J.; Carli, T.; Charlet, M.; Clarke, D.; Clerbaux, B.; Cocks, S.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Cousinou, M.-C.; Cox, B. E.; Cozzika, G.; Cussans, D. G.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; de Roeck, A.; de Wolf, E. A.; Delcourt, B.; Dirkmann, M.; Dixon, P.; Dlugosz, W.; Dollfus, C.; Donovan, K. T.; Dowell, J. D.; Dreis, H. B.; Droutskoi, A.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Elsen, E.; Erdmann, M.; Fahr, A. B.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Formánek, J.; Foster, J. M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Gaede, F.; Garvey, J.; Gayler, J.; Gebauer, M.; Gerhards, R.; Glazov, A.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Gonzalez-Pineiro, B.; Gorelov, I.; Grab, C.; Grässler, H.; Greenshaw, T.; Griffiths, R. K.; Grindhammer, G.; Gruber, A.; Gruber, C.; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, T.; Hampel, M.; Haynes, W. J.; Heinemann, B.; Heinzelmann, G.; Henderson, R. C. W.; Hengstmann, S.; Henschel, H.; Herynek, I.; Hess, M. F.; Hewitt, K.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Höppner, M.; Hoffmann, D.; Holtom, T.; Horisberger, R.; Hudgson, V. L.; Hütte, M.; Ibbotson, M.; İşsever, Ç.; Itterbeck, H.; Jacquet, M.; Jaffre, M.; Janoth, J.; Jansen, D. M.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kalmus, P. I. P.; Kander, M.; Kant, D.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kaufmann, O.; Kausch, M.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Köhler, T.; Köhne, J. H.; Kolanoski, H.; Kolya, S. D.; Korbel, V.; Kostka, P.; Kotelnikov, S. K.; Krämerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Küpper, A.; Küster, H.; Kuhlen, M.; Kurča, T.; Laforge, B.; Landon, M. P. J.; Lange, W.; Langenegger, U.; Lebedev, A.; Lehner, F.; Lemaitre, V.; Levonian, S.; Lindstroem, M.; Linsel, F.; Lipinski, J.; List, B.; Lobo, G.; Lopez, G. C.; Lubimov, V.; Lüke, D.; Lytkin, L.; Magnussen, N.; Mahlke-Krüger, H.; Malinovski, E.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, G.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Mavroidis, T.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Merkel, P.; Metlica, F.; Meyer, A.; Meyer, A.; Meyer, H.; Meyer, J.; Meyer, P.-O.; Migliori, A.; Mikocki, S.; Milstead, D.; Moeck, J.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, D.; Müller, K.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Négri, I.; Newman, P. R.; Newton, D.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Niedzballa, Ch.; Niggli, H.; Nowak, G.; Nunnemann, T.; Oberlack, H.; Olsson, J. E.; Ozerov, D.; Palmen, P.; Panaro, E.; Panitch, A.; Pascaud, C.; Passaggio, S.; Patel, G. D.; Pawletta, H.; Peppel, E.; Perez, E.; Phillips, J. P.; Pieuchot, A.; Pitzl, D.; Pöschl, R.; Pope, G.; Povh, B.; Rabbertz, K.; Reimer, P.; Rick, H.; Reiss, S.; Rizvi, E.; Robmann, P.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rüter, K.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Schacht, P.; Schiek, S.; Schleif, S.; Schleper, P.; von Schlippe, W.; Schmidt, D.; Schmidt, G.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schwab, B.; Sefkow, F.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Sloan, T.; Smirnov, P.; Smith, M.; Solochenko, V.; Soloviev, Y.; Specka, A.; Spiekermann, J.; Spielman, S.; Spitzer, H.; Squinabol, F.; Steffen, P.; Steinberg, R.; Steinhart, J.; Stella, B.; Stellberger, A.; Stiewe, J.; Stößlein, U.; Stolze, K.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Tapprogge, S.; Taševský, M.; Tchernyshov, V.; Tchetchelnitski, S.; Theissen, J.; Thompson, G.; Thompson, P. D.; Tobien, N.; Todenhagen, R.; Truöl, P.; Tsipolitis, G.; Turnau, J.; Tzamariudaki, E.; Uelkes, P.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; van Esch, P.; van Mechelen, P.; Vandenplas, D.; Vazdik, Y.; Verrecchia, P.; Villet, G.; Wacker, K.; Wagener, A.; Wagener, M.; Wallny, R.; Walter, T.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; West, L. R.; Wiesand, S.; Wilksen, T.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wobisch, M.; Wollatz, H.; Wünsch, E.; ŽáČek, J.; Zarbock, D.; Zhang, Z.; Zhokin, A.; Zini, P.; Zomer, F.; Zsembery, J.; Zurnedden, M.

1997-02-01

Deep inelastic e p scattering data, taken with the H1 detector at HERA, are used to study the event shape variables thrust, jet broadening and jet mass in the current hemisphere of the Breit frame over a large range of momentum transfers Q between 7 GeV and 100 GeV. The data are compared with results from e+e- experiments. Using second order QCD calculations and an approach to relate hadronisation effects to power corrections an analysis of the Q dependences of the means of the event shape parameters is presented, from which both the power corrections and the strong coupling constant are determined without any assumption on fragmentation models. The power corrections of all event shape variables investigated follow a 1/Q behaviour and can be described by a common parameter α0.

Deep space network software cost estimation model

NASA Technical Reports Server (NTRS)

Tausworthe, R. C.

1981-01-01

A parametric software cost estimation model prepared for Jet PRopulsion Laboratory (JPL) Deep Space Network (DSN) Data System implementation tasks is described. The resource estimation mdel modifies and combines a number of existing models. The model calibrates the task magnitude and difficulty, development environment, and software technology effects through prompted responses to a set of approximately 50 questions. Parameters in the model are adjusted to fit JPL software life-cycle statistics.

Detection and Identification of Sulfur Compounds in an Australian Jet Fuel

DTIC Science & Technology

2010-06-01

from a number of Australian and south-east Asian refineries that have different fuel finishing processes and methods for sweetening or desulfurising ...comparison to sulfur species that remain in deep hydrodesulfurised or alternate desulfurisation processed AVTUR/FSII fuels of the future. This work...Schmitz, C., Wasserscheid, P. (2001) Deep desulfurisation of diesel fuel by extraction with ionic liquids. Chem. Commun. 2494-2495 39. Dirk, D

Chandra Takes on Heavy Jets and Massive Winds in 4U 1630-47

NASA Astrophysics Data System (ADS)

Neilsen, Joey

2014-11-01

Recently, Díaz Trigo et al. reported the discovery of relativistic baryons in a jet in XMM/ATCA observations of the 2012 outburst of the black hole 4U 1630-47. We present a search for a similarly massive jet earlier in the same outburst using high-resolution X-ray spectra from the Chandra HETGS. Despite a detection of radio emission with ATCA, we find no evidence of a heavy jet in the X-ray spectrum, with tight upper limits on the relativistic emission lines seen by Díaz Trigo eight months later. Instead, we find deep absorption lines from a massive, highly ionized disk wind, whose properties can be probed with detailed photoionization models. We explore several scenarios to explain the two modes of massive outflow in this remarkable black hole system.

An estimate of equatorial wave energy flux at 9- to 90-day periods in the Central Pacific

NASA Technical Reports Server (NTRS)

Eriksen, Charles C.; Richman, James G.

1988-01-01

Deep fluctuations in current along the equator in the Central Pacific are dominated by coherent structures which correspond closely to narrow-band propagating equatorial waves. Currents were measured roughly at 1500 and 3000 m depths at five moorings between 144 and 148 deg W from January 1981 to March 1983, as part of the Pacific Equatorial Ocean Dynamics program. In each frequency band resolved, a single complex empirical orthogonal function accounts for half to three quarters of the observed variance in either zonal or meridional current. Dispersion for equatorial first meridional Rossby and Rossby gravity waves is consistent with the observed vertical-zonal coherence structure. The observations indicate that energy flux is westward and downward in long first meridional mode Rossby waves at periods 45 days and longer, and eastward and downward in short first meridional mode Rossby waves and Rossby-gravity waves at periods 30 days and shorter. A local minimum in energy flux occurs at periods corresponding to a maximum in upper-ocean meridional current energy contributed by tropical instability waves. Total vertical flux across the 9- to 90-day period range is 2.5 kW/m.

Publications of the Jet Propulsion Laboratory 1983

NASA Technical Reports Server (NTRS)

1984-01-01

The Jet propulsion Laboratory (JPL) bibliography describes and indexes by primary author the externally distributed technical reporting, released during calendar year 1983, that resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory. Three classes of publications are included. JPL Publication (81-,82-,83-series, etc.), in which the information is complete for a specific accomplishment, articles published in the open literature, and articles from the quarterly telecommunications and Data Acquisition (TDA) Progress Report (42-series) are included. Each collection of articles in this class of publication presents a periodic survey of current accomplishments by the Deep Space Network as well as other developments in Earth-based radio technology.

Bed load transport by submerged jets

PubMed Central

Francis, J. R. D.; McCreath, P. S.

1979-01-01

Some similarities are presented between the bed load transport of noncohesive grains in long rivers and at a local, jet-induced scour. Experiments are described in which a submerged two-dimensional slot nozzle, inclined downward, eroded a deep sand bed. The rate of erosion at the very beginning of a scour was evaluated and compared with river data by use of the idea of “stream-power.” Empirical relationships for the two cases are similar, although the geometry of the boundaries is quite different. PMID:16592696

First Results From the Ionospheric Extension of WACCM-X During the Deep Solar Minimum Year of 2008

NASA Astrophysics Data System (ADS)

Liu, Jing; Liu, Hanli; Wang, Wenbin; Burns, Alan G.; Wu, Qian; Gan, Quan; Solomon, Stanley C.; Marsh, Daniel R.; Qian, Liying; Lu, Gang; Pedatella, Nicholas M.; McInerney, Joe M.; Russell, James M.; Schreiner, William S.

2018-02-01

New ionosphere and electrodynamics modules have been incorporated in the thermosphere and ionosphere eXtension of the Whole Atmosphere Community Climate Model (WACCM-X), in order to self-consistently simulate the coupled atmosphere-ionosphere system. The first specified dynamics WACCM-X v.2.0 results are compared with several data sets, and with the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM), during the deep solar minimum year. Comparisons with Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite of temperature and zonal wind in the lower thermosphere show that WACCM-X reproduces the seasonal variability of tides remarkably well, including the migrating diurnal and semidiurnal components and the nonmigrating diurnal eastward propagating zonal wavenumber 3 component. There is overall agreement between WACCM-X, TIE-GCM, and vertical drifts observed by the Communication/Navigation Outage Forecast System (C/NOFS) satellite over the magnetic equator, but apparent discrepancies also exist. Both model results are dominated by diurnal variations, while C/NOFS observed vertical plasma drifts exhibit strong temporal variations. The climatological features of ionospheric peak densities and heights (NmF2 and hmF2) from WACCM-X are in general agreement with the results derived from Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) data, although the WACCM-X predicted NmF2 values are smaller, and the equatorial ionization anomaly crests are closer to the magnetic equator compared to COSMIC and ionosonde observations. This may result from the excessive mixing in the lower thermosphere due to the gravity wave parameterization. These data-model comparisons demonstrate that WACCM-X can capture the dynamic behavior of the coupled atmosphere and ionosphere in a climatological sense.

Jets on Comet Borrelly

NASA Image and Video Library

2001-11-03

This very long exposure was taken by NASA Deep Space 1 to show detailed structures in the faint parts of comet Borrelly inner coma. As a result, the nucleus has been greatly over-exposed and its shape appears distorted.

Calling Home in 2003: JPL Roadmap to Standardized TT&C Customer Support

NASA Technical Reports Server (NTRS)

Kurtik, S.; Berner, J.; Levesque, M.

2000-01-01

The telecommunications and Mission Operations Directorate (TMOD at the Jet Propulsion Laboratory (JPL) provides tracking, telemetry and command (TT&C) services for execution of a broad spectrum of deep space missions.

Ocean Inside Saturn Moon Enceladus

NASA Image and Video Library

2014-04-03

Gravity measurements by NASA Cassini spacecraft and Deep Space Network suggest that Saturn moon Enceladus, which has jets of water vapor and ice gushing from its south pole, also harbors a large interior ocean beneath an ice shell.

Effects of Bulk Composition on the Atmospheric Dynamics on Close-in Exoplanets

NASA Astrophysics Data System (ADS)

Zhang, X.; Showman, A. P.

2015-12-01

Depending on the metallicity of the protoplanetary disk, the details of gas accretion during planetary formation, and atmospheric loss during planetary evolution, the atmospheres of sub-Jupiter-sized planets could exhibit a variety of bulk compositions. Examples include hydrogen-dominated atmospheres like Jupiter, more metal-rich atmospheres like Neptune, evaporated atmospheres dominated by helium, or of course carbon dioxide, water vapor, nitrogen, and other heavy molecules as exhibited by terrestrial planets in the solar system. Here we systematically investigate the effects of atmospheric bulk compositions on temperature and wind distributions for tidally locked sub-Jupiter-sized planets using an idealized three-dimensional general circulation model (GCM). Composition—in particular, the molecular mass and specific heat—affect the sound speed, gravity wave speeds, atmospheric scale height, and Rossby deformation radius, and therefore in principle can exert significant controls on the atmospheric circulation, including the day-night temperature difference and other observables. We performed numerous simulations exploring a wide range of molecular masses and molar specific heats. The effect of molecular weight dominates. We found that a higher-molecular-weight atmosphere tends to have a larger day-night temperature contrast, a smaller eastward phase shift in the thermal light curve, and a narrower equatorial super-rotating jet that occurs in a deeper atmosphere. The zonal-mean zonal wind is smaller and more prone to exhibit a latitudinally alternating pattern in a higher-molecular-weight atmosphere. If the vertical temperature profile is close to adiabatic, molar specific heat will play a significant role in controlling the transition from a divergent flow in the upper atmosphere to a jet-dominated flow in the lower atmosphere. We are also working on analytical theories to explain aspects of the simulations relevant for possible observables on tidally locked exoplanets, such as the day-night temperature difference, thermal phase shift and root-mean-square of the wind speed. Our analytical predictions are quantitatively compared with our numerical simulations and may provide potential indicators for determining the atmospheric compositions in future observations.

They Came from the Deep in the Supernova: The Origin of TiC and Metal Subgrains in Presolar Graphite Grains

NASA Astrophysics Data System (ADS)

Lodders, Katharina

2006-08-01

A new formation scenario for TiC and Fe-Ni metal inclusions in presolar graphite grains of supernova origin is described. The mineralogy and chemistry require condensation of Fe-Ni titanides from Fe-, Ni-, and Ti-rich gaseous ejecta, subsequent carburization to make TiC and metal, and encapsulation into graphite. Titanides only condense if Si is depleted relative to heavier elements, which requires α-rich freeze-out and a deep mass cut for the supernova ejecta. This Si-poor core material must remain unmixed with other supernova zones until the titanides condense. This can be accomplished by transport of core ejecta in bipolar jets through the major expanding supernova zone ejecta. If the jets stall in regions dominated by C-rich ejecta such as the C-He zone, where graphite condenses, thermochemically favored in situ carburization of the titanides-either before or during encapsulation into condensing graphite-leads to a TiC-and-metal composite. This scenario agrees with theoretical models and observations of asymmetric core collapse in supernovae that are associated with bipolar jets loaded with iron-peak elements.

Jupiter's atmospheric jet streams extend thousands of kilometres deep.

PubMed

Kaspi, Y; Galanti, E; Hubbard, W B; Stevenson, D J; Bolton, S J; Iess, L; Guillot, T; Bloxham, J; Connerney, J E P; Cao, H; Durante, D; Folkner, W M; Helled, R; Ingersoll, A P; Levin, S M; Lunine, J I; Miguel, Y; Militzer, B; Parisi, M; Wahl, S M

2018-03-07

The depth to which Jupiter's observed east-west jet streams extend has been a long-standing question. Resolving this puzzle has been a primary goal for the Juno spacecraft, which has been in orbit around the gas giant since July 2016. Juno's gravitational measurements have revealed that Jupiter's gravitational field is north-south asymmetric, which is a signature of the planet's atmospheric and interior flows. Here we report that the measured odd gravitational harmonics J 3 , J 5 , J 7 and J 9 indicate that the observed jet streams, as they appear at the cloud level, extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000  kilometres. By inverting the measured gravity values into a wind field, we calculate the most likely vertical profile of the deep atmospheric and interior flow, and the latitudinal dependence of its depth. Furthermore, the even gravity harmonics J 8 and J 10 resulting from this flow profile also match the measurements, when taking into account the contribution of the interior structure. These results indicate that the mass of the dynamical atmosphere is about one per cent of Jupiter's total mass.

Formation of jets in Comet 19P/Borrelly by subsurface geysers

USGS Publications Warehouse

Yelle, R.V.; Soderblom, L.A.; Jokipii, J.R.

2004-01-01

Observations of the inner coma of Comet 19P/Borrelly with the camera on the Deep Space 1 spacecraft revealed several highly collimated dust jets emanating from the nucleus. The observed jets can be produced by acceleration of evolved gas from a subsurface cavity through a narrow orifice to the surface. As long as the cavity is larger than the orifice, the pressure in the cavity will be greater than the ambient pressure in the coma and the flow from the geyser will be supersonic. The gas flow becomes collimated as the sound speed is approached and dust entrainment in the gas flow creates the observed jets. Outside the cavity, the expanding gas loses its collimated character, but the density drops rapidly decoupling the dust and gas, allowing the dust to continue in a collimated beam. The hypothesis proposed here can explain the jets seen in the inner coma of Comet 1P/Halley as well, and may be a primary mechanism for cometary activity. ?? 2003 Published by Elsevier Inc.

Zonally resolved impact of ENSO on the stratospheric circulation and water vapor entry values

NASA Astrophysics Data System (ADS)

Konopka, Paul; Ploeger, Felix; Tao, Mengchu; Riese, Martin

2016-10-01

Based on simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) for the period 1979-2013, with model transport driven by the ECMWF ERA-Interim reanalysis, we discuss the impact of the El Niño Southern Oscillation (ENSO) on the variability of the dynamics, water vapor, ozone, and mean age of air (AoA) in the tropical lower stratosphere during boreal winter. Our zonally resolved analysis at the 390 K potential temperature level reveals that not only (deseasonalized) ENSO-related temperature anomalies are confined to the tropical Pacific (180-300°E) but also anomalous wave propagation and breaking, as quantified in terms of the Eliassen-Palm (EP) flux divergence, with strongest local contribution during the La Niña phase. This anomaly is coherent with respective anomalies of water vapor (±0.5 ppmv) and ozone (±100 ppbv) derived from CLaMS being in excellent agreement with the Aura Microwave Limb Sounder observations. Thus, during El Niño a more zonally symmetric wave forcing drives a deep branch of the Brewer-Dobson (BD) circulation. During La Niña this forcing increases at lower levels (≈390 K) over the tropical Pacific, likely influencing the shallow branch of the BD circulation. In agreement with previous studies, wet (dry) and young (old) tape recorder anomalies propagate upward in the subsequent months following El Niño (La Niña). Using CLaMS, these anomalies are found to be around +0.3 (-0.2) ppmv and -4 (+4) months for water vapor and AoA, respectively. The AoA ENSO anomaly is more strongly affected by the residual circulation (≈2/3) than by eddy mixing (≈1/3).

Global view of the E region irregularity and convection velocities in the high-latitude Southern Hemisphere

NASA Astrophysics Data System (ADS)

Forsythe, Victoriya V.; Makarevich, Roman A.

2017-02-01

Occurrence of the E region plasma irregularities is investigated using two Super Dual Auroral Radar Network (SuperDARN) South Pole (SPS) and Zhongshan (ZHO) radars that sample the same magnetic latitude deep within the high-latitude plasma convection pattern but from two opposite directions. It is shown that the SPS and ZHO velocity distributions and their variations with the magnetic local time are different, with each distribution being asymmetric; i.e., a particular velocity polarity is predominant. This asymmetry in the E region velocity distribution is associated with the bump-on-tail of the distribution near the nominal ion acoustic speed Cs that is most likely due to the Farley-Buneman instability (FBI) echoes or an inflection point of the distribution below nominal Cs that is most likely due to the gradient drift instability echoes. In contrast, the distribution of the convection velocity component was found to be symmetric, i.e., with no bump-on-tail or an inflection point, but with a bias (i.e., uniform shift) toward a particular polarity. It is demonstrated that the asymmetry in the convection pattern between the eastward and westward zonal components is unexpectedly strong, with the westward zonal component being predominant, especially at lower latitudes, while also exhibiting a strong interplanetary magnetic field By dependence. The observations are consistent with the notion that the asymmetry in the E region velocity distribution is highly sensitive to the bias in the convection component caused by the zonal convection component asymmetry and that the bump-on-tail or inflection point features may also depend on the irregularity height and the presence of strong density gradients modifying the FBI threshold value.

An Explanation for Saturn's Hexagon

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2015-08-01

For over three decades, weve been gathering observations of the mysterious hexagonal cloud pattern encircling Saturns north pole. Now, researchers believe they have a model that can better explain its formation.Fascinating GeometrySaturns northern Hexagon is a cloud band circling Saturns north pole at 78 N, first observed by the Voyager flybys in 198081. This remarkable pattern has now persisted for more than a Saturn year (29.5 Earth years).Eight frames demonstrating the motion within Saturns Hexagon. Click to watch the animation! The view is from a reference frame rotating with Saturn. [NASA/JPL-Caltech/SSI/Hampton University]Observations by Voyager and, more recently, Cassini have helped to identify many key characteristics of this bizarre structure. Two interesting things weve learned are:The Hexagon is associated with an eastward zonal jet moving at more than 200 mph.The cause of the Hexagon is believed to be a jet stream, similar to the ones that we experience on Earth. The path of the jet itself appears to follow the hexagons outline.The Hexagon rotates at roughly the same rate as Saturns overall rotation.While we observe individual storms and cloud patterns moving at different speeds within the Hexagon, the vertices of the Hexagon move at almost exactly the same rotational speed as that of Saturn itself.Attempts to model the formation of the Hexagon with a jet stream have yet to fully reproduce all of the observed features and behavior. But now, a team led by Ral Morales-Juberas of the New Mexico Institute of Mining and Technology believes they have created a model that better matches what we see.Simulating a Meandering JetThe team ran a series of simulations of an eastward, Gaussian-profile jet around Saturns pole. They introduced small perturbations to the jet and demonstrated that, as a result of the perturbations, the jet can meander into a hexagonal shape. With the initial conditions of the teams model, the meandering jet is able to settle into a stable hexagonal shape that rotates with very nearly the same period as Saturns rotational period.The formation of this hexagon depends on factors such as the initial amplitude and curvature of the jet. The models treatment of the wind profile within Saturns atmosphere is another key component that allowed them to match the observed characteristics of the Hexagon, such as its shape, vorticity behavior, temperature gradient, and seasonal stability.BonusThe gif below shows part of an animation the authors produced of the jet evolution in their model. You can see a hexagon begin to develop at around 230 days into the simulation, and by about 400 days it becomes stable and non-rotating (were looking at it from a reference frame rotating with Saturn). The full animation can be viewed here. [Morales-Juberas et al., 2015]CitationR. Morales-Juberas et al.2015 ApJ 806 L18 doi:10.1088/2041-8205/806/1/L18

A Better MOC Index: AMOC-θ/S in the North Atlantic Ocean: Spatial Circulation, Water-mass Transformation and Heat Transport on the Temperature/Salinity Plane

NASA Astrophysics Data System (ADS)

Rhines, P. B.; Xu, X.; Chassignet, E.; Schmitz, W. J., Jr.

2016-02-01

An eddy-resolving HYCOM circulation model (driven by a reanalysis atmosphere) shows the structure of the North Atlantic meridional overturning circulation (AMOC), heat transport (MHT) and freshwater transport (MFWT). We project the zonal-mean lateral volume transport, called V(θ,S,y), onto the potential temperature/salinity (θ/S-) plane, and `collapse' V into four zonally integrated volume-transport stream-functions with respect to potential density σ, θ, S and vertical coordinate. The figure shows V(θ,S,y) at 4 latitudes, y, labeled a-d, with northward volume transport in red, southward in blue; Sverdrups of transport are inscribed in σ-bands. Collapsing V onto overturning streamfunctions loses the connection with classic water masses, the hydrologic cycle and convective mode-water production. It is essential that the model resolve boundary currents and the dense northern overflows: model and observations show the dominance of basin-scale AMOC in both MHT and MFWT with potential density, σ, as the vertical coordinate... but much less so with z as a vertical coordinate. With adequate resolution of deep sinking, the Lower North Atlantic Deep Water contributes significantly to MHT. Time-mean MHT and MFWT are dominated by 5-year mean-fields: contributions from annual cycles of velocity and θ are surprisingly small. Quantitative comparison between model and observations at 26N and in the subpolar gyre is supportive of these results. Yet isopycnal processes involving lateral gyres and wind forcing are important. They concentrate the activity of the MOC near western boundaries where essential water-mass transformation (WMT) takes place. V(θ,S,y) transport adds thermohaline `spice' to the MOC, revealing both isopycnal and diapycnal mixing and transport and connects directly with classical water masses. 3-dimensional maps of diapycnal and isopycnal mixing/transport connect internal and externally driven WMT and transports. Particularly important transformation sites are the downslope overflow regions, boundary current extensions (Gulf Stream/North Atlantic Current), mode-water convection sites, deep western boundary currents where topographic transitions occur, and frontal regions (Newfoundland Basin) where northward and southward AMOC branches brush against one another.

A Multi-wavenumber Theory for Eddy Diffusivities: Applications to the DIMES Region

NASA Astrophysics Data System (ADS)

Chen, R.; Gille, S. T.; McClean, J.; Flierl, G.; Griesel, A.

2014-12-01

Climate models are sensitive to the representation of ocean mixing processes. This has motivated recent efforts to collect observations aimed at improving mixing estimates and parameterizations. The US/UK field program Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES), begun in 2009, is providing such estimates upstream of and within the Drake Passage. This region is characterized by topography, and strong zonal jets. In previous studies, mixing length theories, based on the assumption that eddies are dominated by a single wavenumber and phase speed, were formulated to represent the estimated mixing patterns in jets. However, in spite of the success of the single wavenumber theory in some other scenarios, it does not effectively predict the vertical structures of observed eddy diffusivities in the DIMES area. Considering that eddy motions encompass a wide range of wavenumbers, which all contribute to mixing, in this study we formulated a multi-wavenumber theory to predict eddy mixing rates. We test our theory for a domain encompassing the entire Southern Ocean. We estimated eddy diffusivities and mixing lengths from one million numerical floats in a global eddying model. These float-based mixing estimates were compared with the predictions from both the single-wavenumber and the multi-wavenumber theories. Our preliminary results in the DIMES area indicate that, compared to the single-wavenumber theory, the multi-wavenumber theory better predicts the vertical mixing structures in the vast areas where the mean flow is weak; however in the intense jet region, both theories have similar predictive skill.

Structure of the Venus middle atmosphere: Venera 15 fourier spectrometry data revisited

NASA Astrophysics Data System (ADS)

Zasova, L. V.; Khatountsev, I. A.; Moroz, V. I.; Ignatiev, N. I.

1999-01-01

The data obtained by Infrared Fourier Spectrometer on board Venera 15 Orbiter are revisited. The new database of temperature and aerosol profiles is created for the altitude range 55-100 km. The main improvements concern the involving of the whole spectral range free from absorption by any gases but CO2 into the temperature retrieval procedure. Besides the CO2 15 μm fundamental band, this range also includes the weak hot and isotopic CO2 bands. HITRAN-96 spectral database was used for calculation of the gaseous absorption coefficients. The diurnal variations at the isobaric levels are investigated. At low latitudes at the altitude h > 85 km a minimal temperature is observed in the afternoon, and a maximal one is on the morning day side. The temperature differences reach 20 K near 0.1 mb level. The temperature difference changes its sign below 1 mb level: in the afternoon it is warmer by more than 10 K than in the morning. The density of the clouds at all latitudes is found to be higher in the afternoon than in the morning. In the coldest parts of the `cold collar' the clouds are found to be composed of the mode 3 particles. The thermal zonal wind field reveals the presence of the midlatitude jet, connected with the `cold collar'. The low latitude jet near 85 km, connected with the temperature inversion above this level, is observed. It is also possible that another low latitude jet exists near the cloud tops at low latitudes.

On the global circulation and the hurricane system of the Jovian atmosphere

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Meada, K.; Harris, I.

1981-01-01

An argument is made to support the proposal that Jupiter's red spot and the white and brown ovals are hurricanes or cyclones. Against the background of a convectively unstable troposphere, the general condition exists for the formation of hurricanes. The energy Jupiter emits must be transported upwards through the troposphere. If that transport is accelerated by the prevailing upward motions in the solar driven multicellular meridional circulation, eastward jets develop such as observed in the l region. But if that vertical transport is impeded by the prevailing downward motions in the meridional circulation, the atmosphere reacts and tends to maintain the process through the development of hurricanes. Dynamically induced by solar differential heating, an ordered latitudinal structure with alternating stability and instability is impressed on the troposphere to form alternating zonal strata where hurricanes are forbidden and permitted, respectively.

Thermal structure and dynamics of Saturn's northern springtime disturbance

USGS Publications Warehouse

Fletcher, L.N.; Hesman, B.E.; Irwin, P.G.J.; Baines, K.H.; Momary, T.W.; Sanchez-Lavega, A.; Flasar, F.M.; Read, P.L.; Orton, G.S.; Simon-Miller, A.; Hueso, R.; Bjoraker, G.L.; Mamoutkine, A.; Del, Rio-Gaztelurrutia; Gomez, J.M.; Buratti, B.; Clark, R.N.; Nicholson, P.D.; Sotin, Christophe

2011-01-01

Saturn’s slow seasonal evolution was disrupted in 2010–2011 by the eruption of a bright storm in its northern spring hemisphere. Thermal infrared spectroscopy showed that within a month, the resulting planetary-scale disturbance had generated intense perturbations of atmospheric temperatures, winds, and composition between 20° and 50°N over an entire hemisphere (140,000 kilometers). The tropospheric storm cell produced effects that penetrated hundreds of kilometers into Saturn’s stratosphere (to the 1-millibar region). Stratospheric subsidence at the edges of the disturbance produced “beacons” of infrared emission and longitudinal temperature contrasts of 16 kelvin. The disturbance substantially altered atmospheric circulation, transporting material vertically over great distances, modifying stratospheric zonal jets, exciting wave activity and turbulence, and generating a new cold anticyclonic oval in the center of the disturbance at 41°N.

Deep Space 1 Ion Engine Completed a 3-Year Journey

NASA Technical Reports Server (NTRS)

Sovey, James S.; Patterson, Michael J.; Rawlin, Vincent K.; Hamley, John A.

2001-01-01

A xenon ion engine and power processor system, which was developed by the NASA Glenn Research Center in partnership with the Jet Propulsion Laboratory and Boeing Electron Dynamic Devices, completed nearly 3 years of operation aboard the Deep Space 1 spacecraft. The 2.3-kW ion engine, which provided primary propulsion and two-axis attitude control, thrusted for more than 16,000 hr and consumed more than 70 kg of xenon propellant. The Deep Space 1 spacecraft was launched on October 24, 1998, to validate 12 futuristic technologies, including the ion-propulsion system. After the technology validation process was successfully completed, the Deep Space 1 spacecraft flew by the small asteroid Braille on July 29, 1999. The final objective of this mission was to encounter the active comet Borrelly, which is about 6 miles long. The ion engine was on a thrusting schedule to navigate the Deep Space 1 spacecraft to within 1400 miles of the comet. Since the hydrazine used for spacecraft attitude control was in short supply, the ion engine also provided two-axis attitude control to conserve the hydrazine supply for the Borrelly encounter. The comet encounter took place on September 22, 2001. Dr. Marc Rayman, project manager of Deep Space 1 at the Jet Propulsion Laboratory said, "Deep Space 1 plunged into the heart of the comet Borrelly and has lived to tell every detail of its spinetingling adventure! The images are even better than the impressive images of comet Halley taken by Europe's Giotto spacecraft in 1986." The Deep Space 1 mission, which successfully tested the 12 high-risk, advanced technologies and captured the best images ever taken of a comet, was voluntarily terminated on December 18, 2001. The successful demonstration of the 2-kW-class ion propulsion system technology is now providing mission planners with off-the-shelf flight hardware. Higher power, next generation ion propulsion systems are being developed for large flagship missions, such as outer planet explorers and sample-return missions.

Publications of the Jet Propulsion Laboratory 1982

NASA Technical Reports Server (NTRS)

1983-01-01

A bibliography of articles concerning topics on the deep space network, data acquisition, telecommunication, and related aerospace studies is presented. A sample of the diverse subjects include, solar energy remote sensing, computer science, Earth resources, astronomy, and satellite communication.

Field testing of jet-grouted pile : [summary].

DOT National Transportation Integrated Search

2014-01-01

In many areas of Florida, local geology dictates the use of deep foundations for transportation structures bridges, noise walls, signage, etc. When concrete piles are used, they are either prestressed at the casting yard, cast in situ through a h...

Animated software training via the internet: lessons learned

NASA Technical Reports Server (NTRS)

Scott, C. J.

2000-01-01

The Mission Execution and Automation Section, Information Technologies and Software Systems Division at the Jet Propulsion Laboratory, recently delivered an animated software training module for the TMOD UPLINK Consolidation Task for operator training at the Deep Space Network.

Collins azimuthal asymmetries of hadron production inside jets

DOE PAGES

Kang, Zhong -Bo; Prokudin, Alexei; Ringer, Felix; ...

2017-10-18

Here, we investigate the Collins azimuthal asymmetry of hadrons produced inside jets in transversely polarized proton-proton collisions. Recently, the quark transversity distributions and the Collins fragmentation functions have been extracted within global analyses from data of the processes semi-inclusive deep inelastic scattering and electron-positron annihilation. We calculate the Collins azimuthal asymmetry for charged pions inside jets using these extractions for RHIC kinematics at center-of-mass energies of 200 and 500 GeV. We compare our results with recent data from the STAR Collaboration at RHIC and find good agreement, which confirms the universality of the Collins fragmentation functions. In addition, we furthermore » explore the impact of transverse momentum dependent evolution effects.« less

Collins azimuthal asymmetries of hadron production inside jets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Zhong -Bo; Prokudin, Alexei; Ringer, Felix

Here, we investigate the Collins azimuthal asymmetry of hadrons produced inside jets in transversely polarized proton-proton collisions. Recently, the quark transversity distributions and the Collins fragmentation functions have been extracted within global analyses from data of the processes semi-inclusive deep inelastic scattering and electron-positron annihilation. We calculate the Collins azimuthal asymmetry for charged pions inside jets using these extractions for RHIC kinematics at center-of-mass energies of 200 and 500 GeV. We compare our results with recent data from the STAR Collaboration at RHIC and find good agreement, which confirms the universality of the Collins fragmentation functions. In addition, we furthermore » explore the impact of transverse momentum dependent evolution effects.« less

Tsunami Generation from Asteroid Airburst and Ocean Impact and Van Dorn Effect

NASA Technical Reports Server (NTRS)

Robertson, Darrel

2016-01-01

Airburst - In the simulations explored energy from the airburst couples very weakly with the water making tsunami dangerous over a shorter distance than the blast for asteroid sizes up to the maximum expected size that will still airburst (approx.250MT). Future areas of investigation: - Low entry angle airbursts create more cylindrical blasts and might couple more efficiently - Bursts very close to the ground will increase coupling - Inclusion of thermosphere (>80km altitude) may show some plume collapse effects over a large area although with much less pressure center dot Ocean Impact - Asteroid creates large cavity in ocean. Cavity backfills creating central jet. Oscillation between the cavity and jet sends out tsunami wave packet. - For deep ocean impact waves are deep water waves (Phase speed = 2x Group speed) - If the tsunami propagation and inundation calculations are correct for the small (<250MT) asteroids in these simulations where they impact deep ocean basins, the resulting tsunami is not a significant hazard unless particularly close to vulnerable communities. Future work: - Shallow ocean impact. - Effect of continental shelf and beach profiles - Tsunami vs. blast damage radii for impacts close to populated areas - Larger asteroids below presumed threshold of global effects (Ø200 - 800m).

Role of Seasonal Transitions and Westerly Jets in East Asian Paleoclimate

NASA Astrophysics Data System (ADS)

Chiang, J. C. H.; Fung, I. Y.; Wu, C. H.; Cai, Y.; Edman, J. P.; Liu, Y.; Day, J. A.; Bhattacharya, T.; Mondal, Y.; Labrousse, C.

2015-12-01

The summer rainfall climate of East Asia underwent large and abrupt changes during past climates. However, current interpretations of said changes are typically formulated in terms of modulation of summer monsoon intensity, and do not account for the known complexity in the seasonal evolution of East Asian rainfall, which exhibits sharp transition from the Spring regime to the Meiyu, and then again from the Meiyu to the Summer regime. We explore the interpretation that East Asian rainfall climate undergoes a modulation of its seasonality during said paleoclimate changes. Following previous suggestions we focus on role of the westerlies over Asia, that its latitude relative to Tibet is critical in determining the stepwise transitions in East Asian rainfall seasons. In support of this linkage, we show from observational data that the interannual co-variation of June (July-August) rainfall and upper tropospheric zonal winds show properties consistent with an altered timing of the transition to the Meiyu (Summer), and with more northward-shifted westerlies for earlier transitions. We similarly suggest that East Asian paleoclimate changes resulted from an altered timing in the northward evolution of the jet and hence the seasonal transitions, in particular the transition of the jet from south of the Plateau to the north. In an extreme scenario - which we speculate the climate system tended towards during stadial (cold) phases of D/O stadials and periods of low Northern Hemisphere summer insolation - the jet does not jump north of the Plateau, essentially keeping East Asia in prolonged Spring conditions. We argue that this hypothesis provides a viable explanation for a key paleoproxy signature of D/O stadials over East Asia, namely the heavier mean d18O of precipitation as recorded in speleothem records. The southward jet position prevents the low-level monsoonal flow - which is isotopically light - from penetrating into the interior of East Asia; as such, precipitation there will be heavier, consistent with speleothem records. This hypothesis can also explain other key evidences of East Asian paleoclimate changes, in particular the occurrence of dusty conditions during North Atlantic stadials, and the southward migration of the Holocene optimal rainfall.

Ion-neutral Coupling During Deep Solar Minimum

NASA Technical Reports Server (NTRS)

Huang, Cheryl Y.; Roddy, Patrick A.; Sutton, Eric K.; Stoneback, Russell; Pfaff, Robert F.; Gentile, Louise C.; Delay, Susan H.

2013-01-01

The equatorial ionosphere under conditions of deep solar minimum exhibits structuring due to tidal forces. Data from instruments carried by the Communication Navigation Outage Forecasting System (CNOFS) which was launched in April 2008 have been analyzed for the first 2 years following launch. The Planar Langmuir Probe (PLP), Ion Velocity Meter (IVM) and Vector Electric Field Investigation (VEFI) all detect periodic structures during the 20082010 period which appear to be tides. However when the tidal features detected by these instruments are compared, there are distinctive and significant differences between the observations. Tides in neutral densities measured by the Gravity Recovery and Climate Experiment (GRACE) satellite were also observed during June 2008. In addition, Broad Plasma Decreases (BPDs) appear as a deep absolute minimum in the plasma and neutral density tidal pattern. These are co-located with regions of large downward-directed ion meridional velocities and minima in the zonal drifts, all on the nightside. The region in which BPDs occur coincides with a peak in occurrence rate of dawn depletions in plasma density observed on the Defense Meterological Satellite Program (DMSP) spacecraft, as well as a minimum in radiance detected by UV imagers on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) and IMAGE satellites

Azimuthal transverse single-spin asymmetries of inclusive jets and charged pions within jets from polarized-proton collisions at √{s }=500 GeV

NASA Astrophysics Data System (ADS)

Adamczyk, L.; Adams, J. R.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Ajitanand, N. N.; Alekseev, I.; Anderson, D. M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Barish, K.; Behera, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Brown, D.; Bryslawskyj, J.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chankova-Bunzarova, N.; Chatterjee, A.; Chattopadhyay, S.; Chen, X.; Chen, X.; Chen, J. H.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; Dedovich, T. G.; Deng, J.; Deppner, I. M.; Derevschikov, A. A.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Dunlop, J. C.; Efimov, L. G.; Elsey, N.; Engelage, J.; Eppley, G.; Esha, R.; Esumi, S.; Evdokimov, O.; Ewigleben, J.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Federicova, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Fujita, J.; Fulek, L.; Gagliardi, C. A.; Geurts, F.; Gibson, A.; Girard, M.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Harlenderova, A.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Herrmann, N.; Hirsch, A.; Horvat, S.; Huang, B.; Huang, T.; Huang, X.; Huang, H. Z.; Humanic, T. J.; Huo, P.; Igo, G.; Jacobs, W. W.; Jentsch, A.; Jia, J.; Jiang, K.; Jowzaee, S.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kapukchyan, D.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z.; Kikoła, D. P.; Kim, C.; Kisel, I.; Kisiel, A.; Kochenda, L.; Kocmanek, M.; Kollegger, T.; Kosarzewski, L. K.; Kraishan, A. F.; Krauth, L.; Kravtsov, P.; Krueger, K.; Kulathunga, N.; Kumar, L.; Kvapil, J.; Kwasizur, J. H.; Lacey, R.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, W.; Li, Y.; Li, C.; Lidrych, J.; Lin, T.; Lisa, M. A.; Liu, F.; Liu, P.; Liu, Y.; Liu, H.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Luo, S.; Ma, G. L.; Ma, L.; Ma, R.; Ma, Y. G.; Magdy, N.; Majka, R.; Mallick, D.; Margetis, S.; Markert, C.; Matis, H. S.; Mayes, D.; Meehan, K.; Mei, J. C.; Miller, Z. W.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mizuno, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nemes, D. B.; Nie, M.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Nonaka, T.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Quintero, A.; Ramachandran, S.; Ray, R. L.; Reed, R.; Rehbein, M. J.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roth, J. D.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Salur, S.; Sandweiss, J.; Saur, M.; Schambach, J.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Schweid, B. R.; Seger, J.; Sergeeva, M.; Seto, R.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Shen, W. Q.; Shi, S. S.; Shi, Z.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stewart, D. J.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Sugiura, T.; Sumbera, M.; Summa, B.; Sun, Y.; Sun, X.; Sun, X. M.; Surrow, B.; Svirida, D. N.; Tang, A. H.; Tang, Z.; Taranenko, A.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vasiliev, A. N.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, G.; Wang, Y.; Wang, F.; Wang, Y.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, G.; Xie, W.; Xu, Y. F.; Xu, J.; Xu, Q. H.; Xu, N.; Xu, Z.; Yang, S.; Yang, Y.; Yang, C.; Yang, Q.; Ye, Z.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, Z.; Zhang, J.; Zhang, S.; Zhang, S.; Zhang, J.; Zhang, Y.; Zhang, X. P.; Zhang, J. B.; Zhao, J.; Zhong, C.; Zhou, L.; Zhou, C.; Zhu, X.; Zhu, Z.; Zyzak, M.; STAR Collaboration

2018-02-01

We report the first measurements of transverse single-spin asymmetries for inclusive jet and jet+π± production at midrapidity from transversely polarized proton-proton collisions at √{s }=500 GeV . The data were collected in 2011 with the STAR detector sampled from 23 pb-1 integrated luminosity with an average beam polarization of 53%. Asymmetries are reported for jets with transverse momenta 6

Determination of the strong coupling constant \\varvec{α _s (m_Z)} in next-to-next-to-leading order QCD using H1 jet cross section measurements

NASA Astrophysics Data System (ADS)

Andreev, V.; Baghdasaryan, A.; Begzsuren, K.; Belousov, A.; Bertone, V.; Bolz, A.; Boudry, V.; Brandt, G.; Brisson, V.; Britzger, D.; Buniatyan, A.; Bylinkin, A.; Bystritskaya, L.; Campbell, A. J.; Cantun Avila, K. B.; Cerny, K.; Chekelian, V.; Contreras, J. G.; Cvach, J.; Currie, J.; Dainton, J. B.; Daum, K.; Diaconu, C.; Dobre, M.; Dodonov, V.; Eckerlin, G.; Egli, S.; Elsen, E.; Favart, L.; Fedotov, A.; Feltesse, J.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Gehrmann, T.; Ghazaryan, S.; Goerlich, L.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Grebenyuk, A.; Greenshaw, T.; Grindhammer, G.; Gwenlan, C.; Haidt, D.; Henderson, R. C. W.; Hladkỳ, J.; Hoffmann, D.; Horisberger, R.; Hreus, T.; Huber, F.; Huss, A.; Jacquet, M.; Janssen, X.; Jung, A. W.; Jung, H.; Kapichine, M.; Katzy, J.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kogler, R.; Kostka, P.; Kretzschmar, J.; Krücker, D.; Krüger, K.; Landon, M. P. J.; Lange, W.; Laycock, P.; Lebedev, A.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Malinovski, E.; Martyn, H.-U.; Maxfield, S. J.; Mehta, A.; Meyer, A. B.; Meyer, H.; Meyer, J.; Mikocki, S.; Morozov, A.; Müller, K.; Naumann, Th.; Newman, P. R.; Niebuhr, C.; Niehues, J.; Nowak, G.; Olsson, J. E.; Ozerov, D.; Pascaud, C.; Patel, G. D.; Perez, E.; Petrukhin, A.; Picuric, I.; Pirumov, H.; Pitzl, D.; Plačakytė, R.; Polifka, R.; Rabbertz, K.; Radescu, V.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Šálek, D.; Sankey, D. P. C.; Sauter, M.; Sauvan, E.; Schmitt, S.; Schoeffel, L.; Schöning, A.; Sefkow, F.; Shushkevich, S.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Steder, M.; Stella, B.; Straumann, U.; Sutton, M. R.; Sykora, T.; Thompson, P. D.; Traynor, D.; Truöl, P.; Tsakov, I.; Tseepeldorj, B.; Valkárová, A.; Vallée, C.; Van Mechelen, P.; Vazdik, Y.; Wegener, D.; Wünsch, E.; Žáček, J.; Zhang, Z.; Žlebčík, R.; Zohrabyan, H.; Zomer, F.

2017-11-01

The strong coupling constant α _s is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic ep scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of α _s (m_Z) at the Z-boson mass m_Z are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be α _s (m_Z) =0.1157 (20)_exp (29)_th. Complementary, α _s (m_Z) is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value α _s (m_Z) =0.1142 (28)_tot obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1989-01-01

Archival reports on developments in programs managed by the Jet Propulsion Laboratory's Office of Telecommunications and Data Acquisition are provided. Space communications, radio navigation, radio science, and ground based radio and radio astronomy are discussed. Deep Space Network projects are also discussed.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1985-01-01

Developments in programs managed by the Jet Propulsion Laboratory's Office of Telecommunications and Data acquisition are discussed. Space communications, radio antennas, the Deep Space Network, antenna design, Project SETI, seismology, coding, very large scale integration, downlinking, and demodulation are among the topics covered.

The evolution of the equatorial thermocline and the early Pliocene El Padre mean state

NASA Astrophysics Data System (ADS)

Ford, Heather L.; Ravelo, A. Christina; Dekens, Petra S.; LaRiviere, Jonathan P.; Wara, Michael W.

2015-06-01

The tropical Pacific thermocline strength, depth, and tilt are critical to tropical mean state and variability. During the early Pliocene (~3.5 to 4.5 Ma), the Eastern Equatorial Pacific (EEP) thermocline was deeper and the cold tongue was warmer than today, which resulted in a mean state with a reduced zonal sea surface temperature gradient or El Padre. However, it is unclear whether the deep thermocline was a local feature of the EEP or a basin-wide condition with global implications. Our measurements of Mg/Ca of Globorotalia tumida in a western equatorial Pacific site indicate Pliocene subsurface temperatures warmer than today; thus, El Padre included a basin-wide thermocline that was relatively warm, deep, and weakly tilted. At ~4 Ma, thermocline steepening was coupled to cooling of the cold tongue. Since ~4 Ma, the basin-wide thermocline cooled/shoaled gradually, with implications for thermocline feedbacks in tropical dynamics and the interpretation of TEX86-derived temperatures.

Varied representation of the West Pacific pattern in multiple dynamical seasonal predictions of APCC-MME

NASA Astrophysics Data System (ADS)

Lee, Yun-Young

2017-04-01

West Pacific (WP) teleconnection pattern is one of the well-known primary modes of boreal winter low-frequency variability (LFV) resolved in 500 hPa geopotential height and its phase and amplitude strongly influence regional weather conditions including temperature and rainfall extremes [Baxter and Nigam, 2015; Hsu and Wallace, 1985; Linkin and Nigam, 2008; Mo and Livezey, 1986; Thompson and Wallace, 1998; Wallace and Gutzler, 1981]. This study primary aims to evaluate individual 11 GCMs seasonal hindcasts employed as members of multi-model ensemble (MME) produced in APEC Climate Center (APCC) in representing WP. For the extensive and comprehensive evaluation, this study applied seven verification metrics in three scopes: (a) temporal representation of observed indices, (b) spatial mode separation in the Northern Hemisphere (NH), and (c) regional mode isolated in the preset longitudinal domain. Verification results display quite large inter-model spread. Some models mimic observed index variability while others display large bias of index variability compared to climatology. Basic north-south dipole pattern is mostly well reproduced in both rotated and unrotated loading modes. However, each individual seasonal forecast model exhibits slightly different behavior (e.g. amplification/weakening, zonal and meridional shift, downstream extension and so forth) in representing spatial structure of WP. When taking all 7 metrics into account, one Europe (CMCC) model, one Oceania (POAMA) model and two North America (NASA and NCEP) models are classified as relatively good performers while PNU is classified as a matchless poor performer out of 11. Least WP representing skill of PNU is sort of consistent with the largest bias of NH total variability. This study further tries to examine winter mean biases of individual models and figure out how mean bias is linked to WP representation in model world. Model bias of winter climatology is investigated focusing on six large scale phenomena: East Asian winter monsoon (EAWM), Atlantic dipole, Pacific/Atlantic jets and Pacific/Atlantic Hadley circulations. Changes in structure and amplitude of them are diagnosed in terms of root mean square error, pattern correlation, intensity bias, zonal displacement and/or downstream extension. There is consistent strengthening/downstream extension of Atlantic jet and absence of southern divergence cell of Atlantic Hadley in most seasonal prediction models. It is demonstrated that WP representation has something to do with bias of Atlantic winter climatology (Atlantic dipole and Atlantic jet) from scatter plot and regression analysis. This implies the importance of realistic simulation of winter climatology further upstream for better WP representation. A fundamental conclusion of this study is that the representation of primary WP features varies among individual models of APCC-MME and it is significantly dependent on the deficiencies of some winter mean climatological patterns.

Jupiter’s atmospheric jet streams extend thousands of kilometres deep

NASA Astrophysics Data System (ADS)

Kaspi, Y.; Galanti, E.; Hubbard, W. B.; Stevenson, D. J.; Bolton, S. J.; Iess, L.; Guillot, T.; Bloxham, J.; Connerney, J. E. P.; Cao, H.; Durante, D.; Folkner, W. M.; Helled, R.; Ingersoll, A. P.; Levin, S. M.; Lunine, J. I.; Miguel, Y.; Militzer, B.; Parisi, M.; Wahl, S. M.

2018-03-01

The depth to which Jupiter’s observed east–west jet streams extend has been a long-standing question. Resolving this puzzle has been a primary goal for the Juno spacecraft, which has been in orbit around the gas giant since July 2016. Juno’s gravitational measurements have revealed that Jupiter’s gravitational field is north–south asymmetric, which is a signature of the planet’s atmospheric and interior flows. Here we report that the measured odd gravitational harmonics J3, J5, J7 and J9 indicate that the observed jet streams, as they appear at the cloud level, extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000  kilometres. By inverting the measured gravity values into a wind field, we calculate the most likely vertical profile of the deep atmospheric and interior flow, and the latitudinal dependence of its depth. Furthermore, the even gravity harmonics J8 and J10 resulting from this flow profile also match the measurements, when taking into account the contribution of the interior structure. These results indicate that the mass of the dynamical atmosphere is about one per cent of Jupiter’s total mass.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1990-01-01

Archival reports on developments in programs managed by the Jet Propulsion Laboratory's (JPL) Office of Telecommunications and Data Acquisition (TDA) are given. Space communications, radio navigation, radio science, and ground-based radio and radar astronomy, activities of the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, supporting research and technology, implementation, and operations are reported. Also included is TDA-funded activity at JPL on data and information systems and reimbursable Deep Space Network (DSN) work performed for other space agencies through NASA.

Deep space network resource scheduling approach and application

NASA Technical Reports Server (NTRS)

Eggemeyer, William C.; Bowling, Alan

1987-01-01

Deep Space Network (DSN) resource scheduling is the process of distributing ground-based facilities to track multiple spacecraft. The Jet Propulsion Laboratory has carried out extensive research to find ways of automating this process in an effort to reduce time and manpower costs. This paper presents a resource-scheduling system entitled PLAN-IT with a description of its design philosophy. The PLAN-IT's current on-line usage and limitations in scheduling the resources of the DSN are discussed, along with potential enhancements for DSN application.

Relocation of the Deep Space Network Maintenance Center

NASA Technical Reports Server (NTRS)

Beutler, K. F.

1981-01-01

The Jet Propulsion Laboratory maintains a Deep Space Network (DSN) maintenance center (DMC), whose task is to engineer and manage the repair and calibration program for the electronic and mechanical equipment used in the tracking stations located at Madrid, Spain, and Canberra, Australia. The DMC also manages the Goldstone complex maintenance facility (GCMF), whose task is to repair and calibrate the Goldstone electronic and mechanical equipment. The rationale for moving the facility to Barstow, California, and the benefits derived from the move are discussed.

On the tertiary instability formalism of zonal flows in magnetized plasmas

NASA Astrophysics Data System (ADS)

Rath, F.; Peeters, A. G.; Buchholz, R.; Grosshauser, S. R.; Seiferling, F.; Weikl, A.

2018-05-01

This paper investigates the so-called tertiary instabilities driven by the zonal flow in gyro-kinetic tokamak core turbulence. The Kelvin Helmholtz instability is first considered within a 2D fluid model and a threshold in the zonal flow wave vector kZF>kZF,c for instability is found. This critical scale is related to the breaking of the rotational symmetry by flux-surfaces, which is incorporated into the modified adiabatic electron response. The stability of undamped Rosenbluth-Hinton zonal flows is then investigated in gyro-kinetic simulations. Absolute instability, in the sense that the threshold zonal flow amplitude tends towards zero, is found above a zonal flow wave vector kZF,cρi≈1.3 ( ρi is the ion thermal Larmor radius), which is comparable to the 2D fluid results. Large scale zonal flows with kZF

Probing below the Surface of Mars. ITEA/NASA-JPL Learning Activity.

ERIC Educational Resources Information Center

Urquhart, Mary; Urquhart, Sally

2000-01-01

This activity, developed by NASA's Jet Propulsion Laboratory, involves students in recording and graphing temperature data to learn about NASA's Mars Microprobe Mission, Deep Space 2, and how the properties of a material affect the transfer of heat. (Author/JOW)

On the vertical wind shear of Saturn's Equatorial Jet at cloud level

NASA Astrophysics Data System (ADS)

Sánchez-Lavega, A.; Pérez-Hoyos, S.

2005-08-01

With the aim of retrieving the altitude of cloud features used as zonal wind tracers in Saturn's atmosphere, we have reanalyzed three different sets of photometric and calibrated data corresponding to the Voyager epoch 1979-1981 (ground-based in 1979, Voyager 2 PPS and ISS observations in 1981), and we have analyze a new set of Hubble Space Telescope images for 2004. This analysis is put in the perspective of our previous HST study for 1994-2003 (Pérez-Hoyos et al., Icarus, 176, 155. 2005). A common result is found that the individual cloud tracers are embedded within a variable tropospheric haze. According to our models, the Voyager 2 ISS images locate the cloud tracers moving with zonal velocities of 455 to 465 (± 2) m/s at a pressure level of 360 ± 140 mbar. For HST observations, the cloud tracers moving with zonal wind speeds of 280 ± 10 m/s, locate at a pressure level of about 50 ± 10 mbar. All these values are calculated in the latitude 3 deg North. The speed difference, if interpreted as a vertical wind shear (Porco et al., Science, 307, 1226. 2005), requires a change of 90 m/s per scale height, two times greater than that estimated from Cassini CIRS data (Flasar et al., Science, 307, 1247, 2005). We also perform an initial guess on Cassini ISS vertical sounding levels, retrieving values compatible with the HST ones but not with Voyager wind measurements. We conclude that the wind speed velocity differences measured between 1979-81 and 2004 in the upper troposphere cannot be solely explained as a wind shear effect and demand dynamical processes. We discuss the possible action of Rossby waves or an intrinsic circulation change in the ammonia cloud layer and above, following a large period of equatorial storm activity. Acknowledgments: This work was supported by MCYT AYA2003-03216, FEDER, and Grupos UPV 15946/2004. S.P.-H. acknowledges a PhD fellowship from the Spanish MEC and R. H. a post-doc contract from Gobierno Vasco.

Modeling the effects of UV variability and the QBO on the troposphere-stratosphere system. Part I: The middle atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balachandran, N.K.; Rind, D.

1995-08-01

Results of experiments with a GCM involving changes in UV input ({plus_minus}25%, {plus_minus}10%, {plus_minus}5% at wavelengths below 0.3 {mu}m) and simulated equatorial QBO are presented, with emphasis on the middle atmosphere response. The UV forcing employed is larger than observed during the last solar cycle and does not vary with wavelength, hence the relationship of these results to those from actual solar UV forcing should be treated with caution. The QBO alters the location of the zero wind line and the horizontal shear of the zonal wind in the low to middle stratosphere, while the UV change alters the magnitudemore » of the polar jet and the vertical shear of the zonal wind. Both mechanisms thus affect planetary wave propagation. The east phase of the QBO leads to tropical cooling and high-latitude warming in the lower stratosphere, with opposite effects in the upper stratosphere. This quadrupole pattern is also seen in the observations. The high-latitude responses are due to altered planetary wave effects, while the model`s tropical response in the upper stratosphere is due to gravity wave drag. Increased UV forcing warms tropical latitudes in the middle atmosphere, resulting in stronger extratropical west winds, an effect which peaks in the upper stratosphere/lower mesosphere with the more extreme UV forcing but at lower altitudes and smaller wind variations with the more realistic forcing. The increased vertical gradient of the zonal wind leads to increased vertical propagation of planetary waves, altering energy convergences and temperatures. The exact altitudes affected depend upon the UV forcing applied. Results with combined QBO and UV forcing show that in the Northern Hemisphere, polar warming for the east QBO is stronger when the UV input is reduced by 25% and 5% as increased wave propagation to high latitudes (east QBO effect) is prevented from then propagating vertically (reduced UV effect). 30 refs., 14 figs., 6 tabs.« less

Turbulence, transport, and zonal flows in the Madison symmetric torus reversed-field pinch

NASA Astrophysics Data System (ADS)

Williams, Z. R.; Pueschel, M. J.; Terry, P. W.; Hauff, T.

2017-12-01

The robustness and the effect of zonal flows in trapped electron mode (TEM) turbulence and Ion Temperature Gradient (ITG) turbulence in the reversed-field pinch (RFP) are investigated from numerical solutions of the gyrokinetic equations with and without magnetic external perturbations introduced to model tearing modes. For simulations without external magnetic field perturbations, zonal flows produce a much larger reduction of transport for the density-gradient-driven TEM turbulence than they do for the ITG turbulence. Zonal flows are studied in detail to understand the nature of their strong excitation in the RFP and to gain insight into the key differences between the TEM- and ITG-driven regimes. The zonal flow residuals are significantly larger in the RFP than in tokamak geometry due to the low safety factor. Collisionality is seen to play a significant role in the TEM zonal flow regulation through the different responses of the linear growth rate and the size of the Dimits shift to collisionality, while affecting the ITG only minimally. A secondary instability analysis reveals that the TEM turbulence drives zonal flows at a rate that is twice that of the ITG turbulence. In addition to interfering with zonal flows, the magnetic perturbations are found to obviate an energy scaling relation for fast particles.

Zonal wavefront reconstruction in quadrilateral geometry for phase measuring deflectometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Lei; Xue, Junpeng; Gao, Bo

2017-06-14

There are wide applications for zonal reconstruction methods in slope-based metrology due to its good capability of reconstructing the local details on surface profile. It was noticed in the literature that large reconstruction errors occur when using zonal reconstruction methods designed for rectangular geometry to process slopes in a quadrilateral geometry, which is a more general geometry with phase measuring deflectometry. In this paper, we present a new idea for the zonal methods for quadrilateral geometry. Instead of employing the intermediate slopes to set up height-slope equations, we consider the height increment as a more general connector to establish themore » height-slope relations for least-squares regression. The classical zonal methods and interpolation-assisted zonal methods are compared with our proposal. Results of both simulation and experiment demonstrate the effectiveness of the proposed idea. In implementation, the modification on the classical zonal methods is addressed. Finally, the new methods preserve many good aspects of the classical ones, such as the ability to handle a large incomplete slope dataset in an arbitrary aperture, and the low computational complexity comparable with the classical zonal method. Of course, the accuracy of the new methods is much higher when integrating the slopes in quadrilateral geometry.« less

Jetted tidal disruptions of stars as a flag of intermediate mass black holes at high redshifts

NASA Astrophysics Data System (ADS)

Fialkov, Anastasia; Loeb, Abraham

2017-11-01

Tidal disruption events (TDEs) of stars by single or binary supermassive black holes (SMBHs) brighten galactic nuclei and reveal a population of otherwise dormant black holes. Adopting event rates from the literature, we aim to establish general trends in the redshift evolution of the TDE number counts and their observable signals. We pay particular attention to (I) jetted TDEs whose luminosity is boosted by relativistic beaming and (II) TDEs around binary black holes. We show that the brightest (jetted) TDEs are expected to be produced by massive black hole binaries if the occupancy of intermediate mass black holes (IMBHs) in low-mass galaxies is high. The same binary population will also provide gravitational wave sources for the evolved Laser Interferometer Space Antenna. In addition, we find that the shape of the X-ray luminosity function of TDEs strongly depends on the occupancy of IMBHs and could be used to constrain scenarios of SMBH formation. Finally, we make predictions for the expected number of TDEs observed by future X-ray telescopes finding that a 50 times more sensitive instrument than the Burst Alert Telescope (BAT) on board the Swift satellite is expected to trigger ˜10 times more events than BAT, while 6-20 TDEs are expected in each deep field observed by a telescope 50 times more sensitive than the Chandra X-ray Observatory if the occupation fraction of IMBHs is high. Because of their long decay times, high-redshift TDEs can be mistaken for fixed point sources in deep field surveys and targeted observations of the same deep field with year-long intervals could reveal TDEs.

Dynamics of zonal flows in helical systems.

PubMed

Sugama, H; Watanabe, T-H

2005-03-25

A theory for describing collisionless long-time behavior of zonal flows in helical systems is presented and its validity is verified by gyrokinetic-Vlasov simulation. It is shown that, under the influence of particles trapped in helical ripples, the response of zonal flows to a given source becomes weaker for lower radial wave numbers and deeper helical ripples while a high-level zonal-flow response, which is not affected by helical-ripple-trapped particles, can be maintained for a longer time by reducing their bounce-averaged radial drift velocity. This implies a possibility that helical configurations optimized for reducing neoclassical ripple transport can simultaneously enhance zonal flows which lower anomalous transport.

Application of a planetary wave breaking parameterization to stratospheric circulation statistics

NASA Technical Reports Server (NTRS)

Randel, William J.; Garcia, Rolando R.

1994-01-01

The planetary wave parameterization scheme developed recently by Garcia is applied to statospheric circulation statistics derived from 12 years of National Meteorological Center operational stratospheric analyses. From the data a planetary wave breaking criterion (based on the ratio of the eddy to zonal mean meridional potential vorticity (PV) gradients), a wave damping rate, and a meridional diffusion coefficient are calculated. The equatorward flank of the polar night jet during winter is identified as a wave breaking region from the observed PV gradients; the region moves poleward with season, covering all high latitudes in spring. Derived damping rates maximize in the subtropical upper stratosphere (the 'surf zone'), with damping time scales of 3-4 days. Maximum diffusion coefficients follow the spatial patterns of the wave breaking criterion, with magnitudes comparable to prior published estimates. Overall, the observed results agree well with the parameterized calculations of Garcia.

Autonomous Real-time Detection of Plumes and Jets from Moons and Comets

NASA Astrophysics Data System (ADS)

Wagstaff, Kiri L.; Thompson, David R.; Bue, Brian D.; Fuchs, Thomas J.

2014-10-01

Dynamic activity on the surface of distant moons, asteroids, and comets can manifest as jets or plumes. These phenomena provide information about the interior of the bodies and the forces (gravitation, radiation, thermal) they experience. Fast detection and follow-up study is imperative since the phenomena may be time-varying and because the observing window may be limited (e.g., during a flyby). We have developed an advanced method for real-time detection of plumes and jets using onboard analysis of the data as it is collected. In contrast to prior work, our technique is not restricted to plume detection from spherical bodies, making it relevant for irregularly shaped bodies such as comets. Further, our study analyzes raw data, the form in which it is available on board the spacecraft, rather than fully processed image products. In summary, we contribute a vital assessment of a technique that can be used on board tomorrow's deep space missions to detect, and respond quickly to, new occurrences of plumes and jets.

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Posner, E. C. (Editor)

1987-01-01

Developments in programs managed by the Jet Propulsion Laboratory's Office of Telecommunications and Data Acquisition are discussed. Topics discussed include sorption compression/mechanical expanded hybrid refrigeration, calculated 70-meter antenna performance for offset L-band, systolic arrays and stack decoding, and calibrations of Deep Space Network antennas.

Effects of finite poloidal gyroradius, shaping, and collisions on the zonal flow residuala)

NASA Astrophysics Data System (ADS)

Xiao, Yong; Catto, Peter J.; Dorland, William

2007-05-01

Zonal flow helps reduce and regulate the turbulent transport level in tokamaks. Rosenbluth and Hinton have shown that zonal flow damps to a nonvanishing residual level in collisionless [M. Rosenbluth and F. Hinton, Phys. Rev. Lett. 80, 724 (1998)] and collisional [F. Hinton and M. Rosenbluth, Plasma Phys. Control. Fusion 41, A653 (1999)] banana regime plasmas. Recent zonal flow advances are summarized including the evaluation of the effects on the zonal flow residual by plasma cross-section shaping, shorter wavelengths including those less than an electron gyroradius, and arbitrary ion collisionality relative to the zonal low frequency. In addition to giving a brief summary of these new developments, the analytic results are compared with GS2 numerical simulations [M. Kotschenreuther, G. Rewoldt, and W. Tang, Comput. Phys. Commun. 88, 128 (1991)] to demonstrate their value as benchmarks for turbulence codes.

The impact of climatological model biases in the North Atlantic jet on predicted future circulation change

NASA Astrophysics Data System (ADS)

Simpson, I.

2015-12-01

A long standing bias among global climate models (GCMs) is their incorrect representation of the wintertime circulation of the North Atlantic region. Specifically models tend to exhibit a North Atlantic jet (and associated storm track) that is too zonal, extending across central Europe, when it should tilt northward toward Scandinavia. GCM's consistently predict substantial changes in the large scale circulation in this region, consisting of a localized anti-cyclonic circulation, centered over the Mediterranean and accompanied by increased aridity there and increased storminess over Northern Europe.Here, we present preliminary results from experiments that are designed to address the question of what the impact of the climatological circulation biases might be on this predicted future response. Climate change experiments will be compared in two versions of the Community Earth System Model: the first is a free running version of the model, as typically used in climate prediction; the second is a bias corrected version of the model in which a seasonally varying cycle of bias correction tendencies are applied to the wind and temperature fields. These bias correction tendencies are designed to account for deficiencies in the fast parameterized processes, with an aim to push the model toward a more realistic climatology.While these experiments come with the caveat that they assume the bias correction tendencies will remain constant with time, they allow for an initial assessment, through controlled experiments, of the impact that biases in the climatological circulation can have on future predictions in this region. They will also motivate future work that can make use of the bias correction tendencies to understand the underlying physical processes responsible for the incorrect tilt of the jet.

On the occurrence of the coldest region in the stratosphere and tropical tropopause stability: A study using COSMIC/FORMOSAT-3 satellite measurements

NASA Astrophysics Data System (ADS)

Kumar, V.; Dhaka, S. K.; Choudhary, R. K.; Ho, Shu-Peng; Yoden, S.; Reddy, K. K.

2014-12-01

The occurrence of coldest region in the lower and middle stratosphere has been investigated using COSMIC/FORMASAT-3 radio occultation measurements. Observations from January 2007 to December 2011, comprising of 2,871,811 numbers of occultations uniformly spread over land and sea, have been used in this study. Using vertical profiles of temperature upto 40 km altitude, zonally averaged at each 5° latitude band between 90°N and 90°S, it is shown that the coldest region in the upper atmosphere occurs during winter in high latitude stratosphere (latitudes >45°) in both the hemispheres with southern hemisphere (temperature less than <-85 °C) cooler than northern hemisphere (temperature ~-75 °C). The spatial extent of the region of low temperature region found between 10 km and 30 km altitude, indicating a 20 km vertical thick layer of cold temperature. In the southern hemisphere, such a region of coldest temperature remains for more than six months (April-October), in the Northern hemispheric polar region (~-75 °C) it is seen mostly during four winter months between October and January. Using NCEP-DOE reanalysis data, we show that cold temperature in the stratospheric region coexists with the jet streams prevalent in those regions. Strong wind jet is surmised to make stratosphere colder. The absence of sunlight in the coldest region is known to cause jet streams. Impact of stratospheric quasi-biennial oscillation (QBO) on the sharpness of tropical tropopause (stability) has also been investigated. Observations suggest that during westerly phase of QBO, the stability of the tropopause increases.

Atmospheric dynamical changes as a contributor to deglacial climate variability: results from an ensemble of transient deglacial simulations

NASA Astrophysics Data System (ADS)

Andres, Heather; Tarasov, Lev

2017-04-01

The atmosphere is often assumed to play a passive role in centennial- to millennial-timescale climate variations of the last deglaciation due to its short response times ( years) and the absence of abrupt changes in external climate forcings. Nevertheless, atmospheric dynamical responses to changes in ice sheet topography and albedo can affect the entire Northern Hemisphere through the altering of Rossby stationary wave patterns and changes to the North Atlantic eddy-driven jet. These responses appear sensitive to the particular configuration of Northern Hemisphere land ice, so small changes have the potential to reorganize atmospheric circulation with impacts on precipitation distributions, ocean surface currents and sea ice extent. Indirect proxy evidence, idealized theoretical studies, and "snapshot" simulations performed at different periods during the last glacial cycle indicate that between the Last Glacial Maximum and the preindustrial period the North Atlantic eddy-driven jet weakened, became less zonally-oriented, and exhibited greater variability. How the transition (or transitions) between the glacial atmospheric state and the interglacial state occurred is less clear. To address this question, we performed an ensemble of transient simulations of the last deglaciation using the Planet Simulator coupled atmosphere-ocean-vegetation-sea ice model (PlaSim, at an atmospheric resolution of T42) forced by variants of the GLAC1-D deglacial ice sheet chronology. We characterize simulated changes in stationary wave patterns over this period as well as changes in the strength and position of the North Atlantic eddy-driven jet. In particular, we document the range of timescales for these changes and compare the simulated climate signatures of these transitions to data archives of precipitation and sea ice extent.

The Role of Reversed Equatorial Zonal Transport in Terminating an ENSO Event

NASA Astrophysics Data System (ADS)

Chen, H. C.; Hu, Z. Z.; Huang, B.; Sui, C. H.

2016-02-01

In this study, we demonstrate that a sudden reversal of anomalous equatorial zonal current at the peaking ENSO phase triggers the rapid termination of an ENSO event. Throughout an ENSO cycle, the anomalous equatorial zonal current is strongly controlled by the concavity of the anomalous thermocline meridional structure near the equator. During the ENSO developing phase, the anomalous zonal current in the central and eastern Pacific generally enhances the ENSO growth through its zonal SST advection. In the mature phase of ENSO, however, the equatorial thermocline depth anomalies are reflected in the eastern Pacific and slowly propagate westward off the equator in both hemispheres. As a result, the concavity of the thermocline anomalies near the equator is reversed, i.e., the off-equatorial thermocline depth anomalies become higher than that on the equator for El Niño events and lower for La Niño events. This meridional change of thermocline structure reverses zonal transport rapidly in the central-to-eastern equatorial Pacific, which weakens the ENSO SST anomalies by reversed advection. More importantly, the reversed zonal mass transport weakens the existing zonal tilting of equatorial thermocline and suppresses the thermocline feedback. Both processes are concentrated in the eastern equatorial Pacific and can be effective on subseasonal time scales. These current reversal effects are built-in to the ENSO peak phase and independent of the zonal wind effect on thermocline slope. It functions as an oceanic control on ENSO evolution during both El Niño and La Niña events.

Excitation mechanism of non-migrating tides

NASA Astrophysics Data System (ADS)

Miyoshi, Yasunobu; Pancheva, Dora; Mukhtarov, Plamen; Jin, Hidekatsu; Fujiwara, Hitoshi; Shinagawa, Hiroyuki

2017-04-01

Using an atmosphere-ionosphere coupled model, the excitation source and temporal (seasonal and interannual) variations in non-migrating tides are investigated in this study. We first focus our attention on temporal variations in eastward moving diurnal tide with zonal wavenumber 3 (DE3), which is the largest of all the non-migrating tides in the mesosphere and lower thermosphere (MLT). Our simulation results indicate that upward propagation of the DE3 excited in the troposphere is sensitive to the zonal mean zonal wind in the stratosphere and mesosphere. The DE3 amplitude is enhanced in the region where the vertical shear of the zonal mean zonal wind is positive (westerly shear). Quasi-2-year variation in the DE3 amplitude in the MLT region is generated by quasi-2-year variation in the zonal mean zonal wind between 40 and 70 km, which is modulated by the stratospheric QBO. The excitation mechanisms of SW3 (westward moving semidiurnal tide with zonal wavenumber 3) and SW1 (westward moving semidiurnal tide with zonal wavenumber 1) are also investigated. During equinoxes, the SW3 and SW1 are excited by tropospheric heating (latent heat release and solar radiative heating) associated with cumulus convection in the tropics, and propagate upward into the MLT region. On the other hand, during solstices, SW3 and SW1 are generated in the winter stratosphere and mesosphere through the nonlinear interaction between the stationary planetary wave and migrating semidiurnal tide, and propagate upward to the lower thermosphere. The excitation sources of other non-migrating tides are also discussed.

Enhanced nutrient transport improves the depth-dependent properties of tri-layered engineered cartilage constructs with zonal co-culture of chondrocytes and MSCs.

PubMed

Kim, Minwook; Farrell, Megan J; Steinberg, David R; Burdick, Jason A; Mauck, Robert L

2017-08-01

Biomimetic design in cartilage tissue engineering is a challenge given the complexity of the native tissue. While numerous studies have generated constructs with near-native bulk properties, recapitulating the depth-dependent features of native tissue remains a challenge. Furthermore, limitations in nutrient transport and matrix accumulation in engineered constructs hinders maturation within the central core of large constructs. To overcome these limitations, we fabricated tri-layered constructs that recapitulate the depth-dependent cellular organization and functional properties of native tissue using zonally derived chondrocytes co-cultured with MSCs. We also introduced porous hollow fibers (HFs) and HFs/cotton threads to enhance nutrient transport. Our results showed that tri-layered constructs with depth-dependent organization and properties could be fabricated. The addition of HFs or HFs/threads improved matrix accumulation in the central core region. With HF/threads, the local modulus in the deep region of tri-layered constructs nearly matched that of native tissue, though the properties in the central regions remained lower. These constructs reproduced the zonal organization and depth-dependent properties of native tissue, and demonstrate that a layer-by-layer fabrication scheme holds promise for the biomimetic repair of focal cartilage defects. Articular cartilage is a highly organized tissue driven by zonal heterogeneity of cells, extracellular matrix proteins and fibril orientations, resulting in depth-dependent mechanical properties. Therefore, the recapitulation of the functional properties of native cartilage in a tissue engineered construct requires such a biomimetic design of the morphological organization, and this has remained a challenge in cartilage tissue engineering. This study demonstrates that a layer-by-layer fabrication scheme, including co-cultures of zone-specific articular CHs and MSCs, can reproduce the depth-dependent characteristics and mechanical properties of native cartilage while minimizing the need for large numbers of chondrocytes. In addition, introduction of a porous hollow fiber (combined with a cotton thread) enhanced nutrient transport and depth-dependent properties of the tri-layered construct. Such a tri-layered construct may provide critical advantages for focal cartilage repair. These constructs hold promise for restoring native tissue structure and function, and may be beneficial in terms of zone-to-zone integration with adjacent host tissue and providing more appropriate strain transfer after implantation. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Precision measurement of the longitudinal double-spin asymmetry for inclusive jet production in polarized proton collisions at √s = 200 GeV

DOE PAGES

Adamczyk, L.

2015-08-26

We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, A LL, in polarized pp collisions at center-of-mass energy √s = 200 GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC pp data. Lastly, the measured asymmetries provide evidence at the 3σ level for positive gluon polarization in the Bjorken-x region x > 0.05 .

Publications of the Jet Propulsion Laboratory, 1979

NASA Technical Reports Server (NTRS)

1980-01-01

This bibliography includes 1004 technical reports, released during calendar year 1979, that resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory. Three classes of publications are included: (1) JPL Publications; (2) articles published in the open literature; and (3) articles from the bimonthly Deep Space Network Progress Report. The publications are indexed by: (1) author, (2) subject, and (3) publication type and number. A descriptive entry appears under the name of each author of each publication; an abstract is included with the entry for the primary (first listed) author. Unless designated otherwise, all publications listed are unclassified.

Hadron production in 200 GeV μ-copper and μ-carbon deep inelastic interactions

NASA Astrophysics Data System (ADS)

Arvidson, A.; Aubert, J. J.; Bassompierre, G.; Becks, K. H.; Benchouk, C.; Best, C.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Broll, C.; Brown, S.; Carr, J.; Clifft, R. W.; Cobb, J. H.; Coignet, G.; Combley, F.; Court, G. R.; Crespo, J. M.; D'Agostini, G.; Dalpiaz, P. F.; Dalpiaz, P.; Dau, W. D.; Davies, J. K.; Déclais, Y.; Dobinson, R. W.; Dosselli, U.; Drees, J.; Edwards, A.; Edwards, M.; Favier, J.; Ferrero, M. I.; Flauger, W.; Forsbach, H.; Gabathuler, E.; Gamet, R.; Gayler, J.; Gerhardt, V.; Gössling, C.; Gregory, P.; Haas, J.; Hamacher, K.; Hayman, P.; Henckes, M.; Korbel, V.; Landgraf, U.; Leenen, M.; Maire, M.; Massonnet, L.; Minssieux, H.; Mohr, W.; Montgomery, H. E.; Moser, K.; Mount, R. P.; Nagy, E.; Nassalski, J.; Norton, P. R.; McNicholas, J.; Osborne, A. M.; Payre, P.; Peroni, C.; Pessard, H.; Pietrzyk, U.; Rith, K.; Schneegans, M.; Sloan, T.; Stier, H. E.; Stockhausen, W.; Thénard, J. M.; Thompson, J. C.; Urban, L.; Villers, M.; Wahlen, H.; Whalley, M.; Williams, D.; Williams, W. S. C.; Williamson, J.; Wimpenny, S. J.; European Muon Collaboration

1984-11-01

The measurements of the z and pT2 distribution of hadrons produced in the interactions of 200 GeV muons with copper and carbon nuclei are shown in different xBj and virtual photon energy intervals. Effects of the jet scattering are seen at the lowest virtual photon energies while for energies above 70 GeV there is no evidence of these effects. Comparison with a theoretical model indicates that at high jet energies the parton fragmentation distance is greater than the nuclear radius and that the parton absorption cross section is less than 10 mb.

Generation of zonal magnetic fields by low-frequency dispersive electromagnetic waves in a nonuniform dusty magnetoplasma.

PubMed

Shukla, P K

2004-04-01

It is shown that zonal magnetic fields can be parametrically excited by low-frequency dispersive driftlike compressional electromagnetic (DDCEM) modes in a nonuniform dusty magnetoplasma. For this purpose, we derive a pair of coupled equations which exhibits the nonlinear coupling between DDCEM modes and zonal magnetic fields. The coupled mode equations are Fourier analyzed to derive a nonlinear dispersion relation. The latter depicts that zonal magnetic fields are nonlinearly generated at the expense of the low-frequency DDCEM wave energy. The relevance of our investigation to the transfer of energy from short scale DDCEM waves to long scale zonal magnetic field structures in dark molecular clouds is discussed.

The use of water-jetting technology in prostheses revision surgery-first results of parameter studies on bone and bone cement.

PubMed

Honl, M; Rentzsch, R; Müller, G; Brandt, C; Bluhm, A; Hille, E; Louis, H; Morlock, M

2000-01-01

Water-jet cutting techniques have been used in industrial applications for many different materials. Recently these techniques have been developed into a revolutionary cutting tool for soft tissues in visceral surgery. The present study investigates the usage of this cutting technology for the revision surgery of endoprostheses. In the first part of the study, samples of bovine bone and acrylic bone cement (PMMA) were cut using an industrial jet cutting device with pure water. Below 400 bar, only PMMA was cut; above 400 bar, bone was also cut, but only pressures above 800 bar resulted in clinically useful rates of material removal (cut depth 2. 4 mm at 10 mm/min traverse speed). In the second part of the study, the effect of adding biocompatible abrasives to the water in order to reduce the required pressure was investigated, resulting in a significantly higher removal of material. At 600 bar, PMMA was cut 5. 2 mm deep with plain water and 15.2 mm deep with added abrasives. The quality of the cuts was increased by the abrasive. Though there was no clear selectivity between bone and PMMA any more, the rate of material removal at similar pressures was significantly higher for PMMA than for bone (600 bar: 1.6 mm cut depth for bone samples, 15.2 mm for PMMA). The measured cut depths with either method were not influenced by a change of the cutting direction with respect to the main direction of the osteons in the bone. However, a reduction of the jet surface angle (90 degrees to 23 degrees ) resulted for bone in a significantly lower cut depth at 600 bar (plain water: 0.62 mm vs. 0.06 mm; abrasive: 1.61 mm vs. 0.60 mm). The laboratory experiments indicate that abrasive water jets may be suitable for cutting biomaterials like bone and bone cement. Copyright 2000 John Wiley & Sons, Inc.

Evolution of the eastward shift in the quasi-stationary minimum of the Antarctic total ozone column

NASA Astrophysics Data System (ADS)

Grytsai, Asen; Klekociuk, Andrew; Milinevsky, Gennadi; Evtushevsky, Oleksandr; Stone, Kane

2017-02-01

The quasi-stationary pattern of the Antarctic total ozone has changed during the last 4 decades, showing an eastward shift in the zonal ozone minimum. In this work, the association between the longitudinal shift of the zonal ozone minimum and changes in meteorological fields in austral spring (September-November) for 1979-2014 is analyzed using ERA-Interim and NCEP-NCAR reanalyses. Regressive, correlative and anomaly composite analyses are applied to reanalysis data. Patterns of the Southern Annular Mode and quasi-stationary zonal waves 1 and 3 in the meteorological fields show relationships with interannual variability in the longitude of the zonal ozone minimum. On decadal timescales, consistent longitudinal shifts of the zonal ozone minimum and zonal wave 3 pattern in the middle-troposphere temperature at the southern midlatitudes are shown. Attribution runs of the chemistry-climate version of the Australian Community Climate and Earth System Simulator (ACCESS-CCM) model suggest that long-term shifts of the zonal ozone minimum are separately contributed by changes in ozone-depleting substances and greenhouse gases. As is known, Antarctic ozone depletion in spring is strongly projected on the Southern Annular Mode in summer and impacts summertime surface climate across the Southern Hemisphere. The results of this study suggest that changes in zonal ozone asymmetry accompanying ozone depletion could be associated with regional climate changes in the Southern Hemisphere in spring.

QCD studies in ep collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, W.H.

1997-06-01

These lectures describe QCD physics studies over the period 1992--1996 from data taken with collisions of 27 GeV electrons and positrons with 820 GeV protons at the HERA collider at DESY by the two general-purpose detectors H1 and ZEUS. The focus of these lectures is on structure functions and jet production in deep inelastic scattering, photoproduction, and diffraction. The topics covered start with a general introduction to HERA and ep scattering. Structure functions are discussed. This includes the parton model, scaling violation, and the extraction of F{sub 2}, which is used to determine the gluon momentum distribution. Both low andmore » high Q{sup 2} regimes are discussed. The low Q{sup 2} transition from perturbative QCD to soft hadronic physics is examined. Jet production in deep inelastic scattering to measure {alpha}{sub s}, and in photoproduction to study resolved and direct photoproduction, is also presented. This is followed by a discussion of diffraction that begins with a general introduction to diffraction in hadronic collisions and its relation to ep collisions, and moves on to deep inelastic scattering, where the structure of diffractive exchange is studied, and in photoproduction, where dijet production provides insights into the structure of the Pomeron. 95 refs., 39 figs.« less

Study of dilution, height, and lateral spread of vertical dense jets in marine shallow water.

PubMed

Ahmad, Nadeem; Suzuki, Takayuki

2016-01-01

This study provides information for the design of sea outfalls to dispose of brine from desalination plants into shallow lagoons of the sea. The behavior of vertical dense jets was studied experimentally by discharging cold saline water vertically upward into a tank filled with hot freshwater under stagnant ambient conditions. The minimum return point dilution, μmin, was determined using thermocouples, and the maximum height, Z(m), and the lateral spread, R(sp), of the fountains were determined by observing shadowgraph pictures. The flow was turbulent and the densimetric Froude number Fr(0) varied from 9 to 18.8. Three mixing regimes were identified: deep, intermediate, and impinging mixing regimes. In the intermediate mixing regime, μ(min) and Z(m) were analyzed and compared with the results of deep water studies. The μ(min) and Z(m) values of fountains at an intermediate water depth were found to be higher than those of fountains at deep water depths. In the impinging regime, μ(min) decreases rapidly when a fountain starts to continuously impinge on the water surface, showing a noticeable disturbance in the water surface. Therefore, a good rule of thumb is to reduce the flow through multiport diffusers from desalination plants when the noticeable disturbance is observed from the top water surface.

The impact of resolution on the dynamics of the martian global atmosphere: Varying resolution studies with the MarsWRF GCM

NASA Astrophysics Data System (ADS)

Toigo, Anthony D.; Lee, Christopher; Newman, Claire E.; Richardson, Mark I.

2012-09-01

We investigate the sensitivity of the circulation and thermal structure of the martian atmosphere to numerical model resolution in a general circulation model (GCM) using the martian implementation (MarsWRF) of the planetWRF atmospheric model. We provide a description of the MarsWRF GCM and use it to study the global atmosphere at horizontal resolutions from 7.5° × 9° to 0.5° × 0.5°, encompassing the range from standard Mars GCMs to global mesoscale modeling. We find that while most of the gross-scale features of the circulation (the rough location of jets, the qualitative thermal structure, and the major large-scale features of the surface level winds) are insensitive to horizontal resolution over this range, several major features of the circulation are sensitive in detail. The northern winter polar circulation shows the greatest sensitivity, showing a continuous transition from a smooth polar winter jet at low resolution, to a distinct vertically “split” jet as resolution increases. The separation of the lower and middle atmosphere polar jet occurs at roughly 10 Pa, with the split jet structure developing in concert with the intensification of meridional jets at roughly 10 Pa and above 0.1 Pa. These meridional jets appear to represent the separation of lower and middle atmosphere mean overturning circulations (with the former being consistent with the usual concept of the “Hadley cell”). Further, the transition in polar jet structure is more sensitive to changes in zonal than meridional horizontal resolution, suggesting that representation of small-scale wave-mean flow interactions is more important than fine-scale representation of the meridional thermal gradient across the polar front. Increasing the horizontal resolution improves the match between the modeled thermal structure and the Mars Climate Sounder retrievals for northern winter high latitudes. While increased horizontal resolution also improves the simulation of the northern high latitudes at equinox, even the lowest model resolution considered here appears to do a good job for the southern winter and southern equinoctial pole (although in detail some discrepancies remain). These results suggest that studies of the northern winter jet (e.g., transient waves and cyclogenesis) will be more sensitive to global model resolution that those of the south (e.g., the confining dynamics of the southern polar vortex relevant to studies of argon transport). For surface winds, the major effect of increased horizontal resolution is in the superposition of circulations forced by local-scale topography upon the large-scale surface wind patterns. While passive predictions of dust lifting are generally insensitive to model horizontal resolution when no lifting threshold is considered, increasing the stress threshold produces significantly more lifting in higher resolution simulations with the generation of finer-scale, higher-stress winds due primarily to better-resolved topography. Considering the positive feedbacks expected for radiatively active dust lifting, we expect this bias to increase when such feedbacks are permitted.

Architectural Options for a Future Deep Space Optical Communications Network

NASA Technical Reports Server (NTRS)

Edwards, B. L.; Benjamin, T.; Scozzafava, J.; Khatri, F.; Sharma, J.; Parvin, B.; Liebrecht, P. E.; Fitzgerald, R. J.

2004-01-01

This paper provides an overview of different options at Earth to provide Deep Space optical communication services. It is based mainly on work done for the Mars Laser Communications Demonstration (MLCD) Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It also reports preliminary conclusions from the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telecommunications Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.

Clusters of cyclones encircling Jupiter's poles.

PubMed

Adriani, A; Mura, A; Orton, G; Hansen, C; Altieri, F; Moriconi, M L; Rogers, J; Eichstädt, G; Momary, T; Ingersoll, A P; Filacchione, G; Sindoni, G; Tabataba-Vakili, F; Dinelli, B M; Fabiano, F; Bolton, S J; Connerney, J E P; Atreya, S K; Lunine, J I; Tosi, F; Migliorini, A; Grassi, D; Piccioni, G; Noschese, R; Cicchetti, A; Plainaki, C; Olivieri, A; O'Neill, M E; Turrini, D; Stefani, S; Sordini, R; Amoroso, M

2018-03-07

The familiar axisymmetric zones and belts that characterize Jupiter's weather system at lower latitudes give way to pervasive cyclonic activity at higher latitudes. Two-dimensional turbulence in combination with the Coriolis β-effect (that is, the large meridionally varying Coriolis force on the giant planets of the Solar System) produces alternating zonal flows. The zonal flows weaken with rising latitude so that a transition between equatorial jets and polar turbulence on Jupiter can occur. Simulations with shallow-water models of giant planets support this transition by producing both alternating flows near the equator and circumpolar cyclones near the poles. Jovian polar regions are not visible from Earth owing to Jupiter's low axial tilt, and were poorly characterized by previous missions because the trajectories of these missions did not venture far from Jupiter's equatorial plane. Here we report that visible and infrared images obtained from above each pole by the Juno spacecraft during its first five orbits reveal persistent polygonal patterns of large cyclones. In the north, eight circumpolar cyclones are observed about a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. Cyclonic circulation is established via time-lapse imagery obtained over intervals ranging from 20 minutes to 4 hours. Although migration of cyclones towards the pole might be expected as a consequence of the Coriolis β-effect, by which cyclonic vortices naturally drift towards the rotational pole, the configuration of the cyclones is without precedent on other planets (including Saturn's polar hexagonal features). The manner in which the cyclones persist without merging and the process by which they evolve to their current configuration are unknown.

Striations and preferred eddy tracks triggered by topographic steering of the background flow in the eastern South Pacific

NASA Astrophysics Data System (ADS)

Belmadani, Ali; Concha, Emilio; Donoso, David; Chaigneau, Alexis; Colas, François; Maximenko, Nikolai; Di Lorenzo, Emanuele

2017-04-01

In recent years, persistent quasi-zonal jets or striations have been ubiquitously detected in the world ocean using satellite and in situ data as well as numerical models. This study aims at determining the role of mesoscale eddies in the generation and persistence of striations off Chile in the eastern South Pacific. A 50 year climatological integration of an eddy-resolving numerical ocean model is used to assess the long-term persistence of striations. Automated eddy tracking algorithms are applied to the model outputs and altimetry data. Results reveal that striations coincide with both polarized eddy tracks and the offshore formation of new eddies in the subtropical front and coastal transition zone, without any significant decay over time that discards random eddies as a primary driver of the striations. Localized patches of vortex stretching and relative vorticity advection, alternating meridionally near the eastern edge of the subtropical front, are associated with topographic steering of the background flow in the presence of steep topography, and with baroclinically and barotropically unstable meridional flow. These sinks and sources of vorticity are suggested to generate the banded structure further west, consistently with a β-plume mechanism. On the other hand, zonal/meridional eddy advection of relative vorticity and the associated Reynolds stress covariance are consistent with eddy deformation over rough topography and participate to sustain the striations in the far field. Shear instability of mean striations is proposed to feedback onto the eddy field, acting to maintain the subtropical front eddy streets and thus the striations.

Three-Dimensional Structures of Thermal Tides Simulated by a Venus GCM

NASA Astrophysics Data System (ADS)

Takagi, Masahiro; Sugimoto, Norihiko; Ando, Hiroki; Matsuda, Yoshihisa

2018-02-01

Thermal tides in the Venus atmosphere are investigated by using a GCM named as AFES-Venus. The three-dimensional structures of wind and temperature associated with the thermal tides obtained in our model are fully examined and compared with observations. The result shows that the wind and temperature distributions of the thermal tides depend complexly on latitude and altitude in the cloud layer, mainly because they consist of vertically propagating and trapped modes with zonal wave numbers of 1-4, each of which predominates in different latitudes and altitudes under the influence of mid- and high-latitude jets. A strong circulation between the subsolar and antisolar (SS-AS) points, which is equivalent to a diurnal component of the thermal tides, is superposed on the superrotation. The vertical velocity of SS-AS circulation is about 10 times larger than that of the zonal-mean meridional circulation (ZMMC) in 60-70 km altitudes. It is suggested that the SS-AS circulation could contribute to the material transport, and its upward motion might be related to the UV dark region observed in the subsolar and early afternoon regions in low latitudes. The terdiurnal and quaterdiurnal tides, which may be excited by the nonlinear interactions among the diurnal and semidiurnal tides in middle and high latitudes, are detected in the solar-fixed Y-shape structure formed in the vertical wind field in the upper cloud layer. The ZMMC is weak and has a complex structure in the cloud layer; the Hadley circulation is confined to latitudes equatorward of 30°, and the Ferrel-like one appears in middle and high latitudes.

A potential regulation of jet stream behavior by changes in Arctic cirrus cloud formation mechanism and coverage

NASA Astrophysics Data System (ADS)

Mejia, J.; Mitchell, D. L.; Garnier, A.; Hosseinpour, F.; Avery, M. A.

2017-12-01

Global retrievals of cirrus cloud effective diameter De and mid-cloud temperature T were used to make the cirrus clouds simulated in CAM5 conform with the retrieved De, with the ice fall speeds in CAM5 calculated from the retrieved De. This was done by developing De-T relationships for six latitude zones. Within each latitude zone, seasonal De-T relationships were developed for cirrus over land and for cirrus over ocean (making 48 De-T relationships in total). The recently developed CALIPSO retrieval algorithm is sensitive to the ice crystal number concentration N, which is also retrieved, and it utilizes radiances from the infrared imaging radiometer and backscatter from the CALIPSO lidar. Retrieved De (N) is largest (lowest) between 30S and 30N latitude; a region dominated by anvil cirrus where pre-existing ice strongly favors heterogeneous ice nucleation (henceforth het). Therefore, the De-T relations for this region are considered representative for cirrus formed via het. Outside this region, retrieved De (N) tended to be considerably smaller (higher), presumably due to homogeneous ice nucleation (henceforth hom). Two CAM5 simulations were performed; one where cirrus cloud De is based on the CALIPSO retrievals and one where De-T for het cirrus is applied globally. Differences in net cloud radiative forcing between runs are believed due to differences in cirrus formation mechanism (hom vs. het). Such differences are typically 1.3 W m-2 in the mid-to-high latitudes in the N. Hemisphere excepting summer. These differences imply differences in cirrus cloud heating rates that affect temperatures in the underlying troposphere, which in turn affect the wind fields. The natural cirrus (mixture of hom and het) tend to trap more heat than the het cirrus. Changes in zonal wind fields between simulations suggest that heating by polar cirrus clouds have modifed meridional temperature gradients and thus zonal winds through the thermal wind balance. These changes in heating by polar cirrus clouds can modify the amplitude and meridional position of the midlatitude jet streams, which can lead to more extreme weather. Moreover, the retrievals indicate a doubling of Arctic cirrus coverage during winter, which will also result in increased heating of the underlying troposphere, likely contributing to this same phenomenon.

Wind Patterns in Jupiter's Equatorial Region (Time set 1)

NASA Technical Reports Server (NTRS)

1997-01-01

Wind patterns of Jupiter's equatorial region. This mosaic covers an area of 34,000 kilometers by 22,000 kilometers and was taken using the 756 nanometer (nm) near-infrared continuum filter. The dark region near the center of the mosaic is an equatorial 'hotspot' similar to the Galileo Probe entry site. The near-infrared continuum filter shows the features of Jupiter's main visible cloud deck.

Jupiter's atmospheric circulation is dominated by alternating jets of east/west (zonal) winds. The bands have different widths and wind speeds but have remained constant as long as telescopes and spacecraft have measured them. The top half of these mosaics lies within Jupiter's North Equatorial Belt, a westward (left) current. The bottom half shows part of the Equatorial Zone, a fast moving eastward current. The clouds near the hotspot are the fastest moving features in these mosaics, moving at about 100 meters per second, or 224 miles per hour.

Superimposed on the zonal wind currents is the Jovian 'weather'. The arrows show the winds measured by an observer moving eastward (right) at the speed of the hotspot. (The observer's perspective is that the hotspot is 'still' while the rest of the planet moves around it.) Clouds south of the hotspot appear to be moving towards it, as seen in the flow aligned with cloud streaks to the southwest and in the clockwise flow to the southeast. Interestingly, there is little cloud motion away from the hotspot in any direction. This is consistent with the idea that dry air is converging over this region and sinking, maintaining the cloud-free nature of the hotspot.

North is at the top. The mosaic covers latitudes 1 to 19 degrees and is centered at longitude 336 degrees West. The smallest resolved features are tens of kilometers in size. These images were taken on December 17, 1996, at a range of 1.5 million kilometers by the Solid State Imaging system aboard NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

Isopycnal diffusivity in the tropical North Atlantic oxygen minimum zone

NASA Astrophysics Data System (ADS)

Köllner, Manuela; Visbeck, Martin; Tanhua, Toste; Fischer, Tim

2017-04-01

Isopycnal diffusivity plays an important role in the ventilation of the Eastern Tropical North Atlantic (ETNA) Oxygen Minimum Zone (OMZ). Lateral tracer transport is described by isopycnal diffusivity and mean advection of the tracer (e.g. oxygen), together they account for up to 70% of the oxygen supply for the OMZ. One of the big challenges is to separate diffusivity from advection. Isopycnal diffusivity was estimated to be Ky=(500 ± 200) m2 s-1 and Kx=(1200 ± 600) m2 s-1 by Banyte et. al (2013) from a Tracer Release Experiment (TRE). Hahn et al. (2014) estimated a meridional eddy diffusivity of 1350 m2 s-1 at 100 m depth decaying to less than 300 m2 s-1 below 800 m depth from repeated ship sections of CTD and ADCP data in addition with hydrographic mooring data. Uncertainties of the estimated diffusivities were still large, thus the Oxygen Supply Tracer Release Experiment (OSTRE) was set up to estimate isopycnal diffusivity in the OMZ using a newly developed sampling strategy of a control volume. The tracer was released in 2012 in the core of the OMZ at approximately 410 m depth and mapped after 6, 15 and 29 months in a regular grid. In addition to the calculation of tracer column integrals from vertical tracer profiles a new sampling method was invented and tested during two of the mapping cruises. The mean eddy diffusivity during OSTRE was found to be about (300 ± 130) m2 s-1. Additionally, the tracer has been advected further to the east and west by zonal jets. We compare different analysis methods to estimate isopycnal diffusivity from tracer spreading and show the advantage of the control volume surveys and control box approach. From the control box approach we are estimating the strength of the zonal jets within the OMZ core integrated over the TRE time period. References: Banyte, D., Visbeck, M., Tanhua, T., Fischer, T., Krahmann, G.,Karstensen, J., 2013. Lateral Diffusivity from Tracer Release Experiments in the Tropical North Atlantic Thermocline. Journal of Geophysical Research 118. Hahn, J., Brandt, P., Greatbatch, R., Krahmann, G., Körtzinger, A., 2014. Oxygen variance and meridional oxygen supply in the Tropical North East Atlantic oxygen minimum zone. Climate Dynamics 43, 2999-3024.

Solar-QBO Interaction and Its Impact on Stratospheric Ozone in a Zonally Averaged Photochemical Transport Model of the Middle Atmosphere

DTIC Science & Technology

2007-08-28

Solar- QBO interaction and its impact on stratospheric ozone in a zonally averaged photochemical transport model of the middle atmosphere J. P...investigate the solar cycle modulation of the quasi-biennial oscillation ( QBO ) in stratospheric zonal winds and its impact on stratospheric ozone with an...updated version of the zonally averaged CHEM2D middle atmosphere model. We find that the duration of the westerly QBO phase at solar maximum is 3 months

[Endovascular treatment of acute iliofemoral deep venous thrombosis - our results with catheter-directed thrombolysis and AngioJet].

PubMed

Berencsi, Anikó; Dósa, Edit; Nemes, Balázs; Hüttl, Kálmán; Legeza, Péter; Oláh, Zoltán; Kristóf, Vera; Acsády, György; Sótonyi, Péter

2017-03-01

Most of the patients with iliofemoral thrombosis treated with anticoagulants only are affected with postthrombotic syndrome (PTS) that worsens the patients' quality of life. In the acute phase of proximal deep venous thrombosis (DVT) catheter-directed (CDT) and pharmacomechanical thrombolysis may be a reasonable alternative therapeutic method. Our aim was to summarize our results using these methods. Since 2009 twenty-four patients with iliofemoral DVT were treated with these endovascular procedures and with stenting at our Institution. The median age of the patients was 35.83 ± 15.9 years, the female: male ratio was approximately 2:1. The mean time between the onset of the symptoms and the procedures was eleven days. CDT alone was performed in 8 patients, thrombus aspiration in addition to CDT using AngioJet device in 16 patients; in 19 cases the procedure was completed with venous stenting. During the follow-up we performed US examinations and estimated the severity of PTS by Villalta-scale. The total recanalization-rate was more than 50%, which even improved during the follow-up. The total lysis time and the amount of used recombinant tissue plasminogen activator decreased significantly by applying the AngioJet. We did not find any severe PTS among our patients during the follow-up visits. Our data suggests that these methods can be used efficiently and safely in the treatment of acute iliofemoral DVT.

Dissolved low-molecular weight thiol concentrations from the U.S. GEOTRACES North Atlantic Ocean zonal transect

NASA Astrophysics Data System (ADS)

Swarr, Gretchen J.; Kading, Tristan; Lamborg, Carl H.; Hammerschmidt, Chad R.; Bowman, Katlin L.

2016-10-01

Low-molecular weight thiols, including cysteine and glutathione, are biomolecules involved in a variety of metabolic pathways and act as important antioxidant and metal buffering agents. In this last capacity, they represent a potential mechanism for modulating the bioavailability and biogeochemistry of many trace elements in the ocean, particularly for chalcophilic elements (e.g., Cu, Zn, Cd, Ag and Hg). For this reason, and in the context of the international GEOTRACES program that seeks to understand the biogeochemistry of trace elements in the ocean, we measured the concentration of individual dissolved low-molecular weight thiols during the U.S. GEOTRACES North Atlantic Zonal Transect (USGNAZT). Only two thiols were identified, cysteine and glutathione, in contrast to results from the northeast subarctic Pacific Ocean, where the dipeptides glycine-cysteine and arginine-cysteine were also present and γ-glutamylcysteine was dominant. Concentrations of cysteine and glutathione in the North Atlantic Ocean were lower than in the Pacific and ranged from below detection ( 0.01 nM) to 0.61 nM of cysteine and up to 1.0 nM of glutathione, with cysteine generally more abundant than glutathione. Vertical profiles of cysteine and glutathione were broadly consistent with their biological production, being more abundant in surface water and usually below detection at depths greater than about 200 m. Subsurface concentration maxima, often co-incident with the deep chlorophyll maximum, were frequently observed but not universal. We conclude that cysteine and glutathione do not make up significant portions of complexation capacity for Cu and Zn in the upper open ocean but could be important for Cd, Hg, and potentially other chalcophiles. Extremely low concentrations of cysteine and glutathione in deep water suggest that higher molecular-weight thiols are a more important ligand class for chalcophiles in that portion of the ocean.

Insights Into the Biogeochemical Cycling of Iron, Nitrate, and Phosphate Across a 5,300 km South Pacific Zonal Section (153°E-150°W)

NASA Astrophysics Data System (ADS)

Ellwood, Michael J.; Bowie, Andrew R.; Baker, Alex; Gault-Ringold, Melanie; Hassler, Christel; Law, Cliff S.; Maher, William A.; Marriner, Andrew; Nodder, Scott; Sander, Sylvia; Stevens, Craig; Townsend, Ashley; van der Merwe, Pier; Woodward, E. Malcolm S.; Wuttig, Kathrin; Boyd, Philip W.

2018-02-01

Iron, phosphate, and nitrate are essential nutrients for phytoplankton growth, and hence, their supply into the surface ocean controls oceanic primary production. Here we present a GEOTRACES zonal section (GP13; 30-33°S, 153°E-150°W) extending eastward from Australia to the oligotrophic South Pacific Ocean gyre outlining the concentrations of these key nutrients. Surface dissolved iron concentrations are elevated at >0.4 nmol L-1 near continental Australia (west of 165°E) and decreased eastward to ≤0.2 nmol L-1 (170°W-150°W). The supply of dissolved iron into the upper ocean (<100 m) from the atmosphere and vertical diffusivity averaged 11 ± 10 nmol m-2 d-1. In the remote South Pacific Ocean (170°W-150°W), atmospherically sourced iron is a significant contributor to the surface dissolved iron pool with average supply contribution of 23 ± 17% (range 3% to 55%). Surface water nitrate concentrations averaged 5 ± 4 nmol L-1 between 170°W and 150°W, while surface water phosphate concentrations averaged 58 ± 30 nmol L-1. The supply of nitrogen into the upper ocean is primarily from deeper waters (24-1647 μmol m-2 d-1) with atmospheric deposition and nitrogen fixation contributing <1% to the overall flux along the eastern part of the transect. The deep water N:P ratio averaged 14.5 ± 0.5 but declined to <1 above the deep chlorophyll maximum (DCM) indicating a high N:P assimilation ratio by phytoplankton leading to almost quantitative removal of nitrate. The supply stoichiometry for iron and nitrogen relative to phosphate at and above the DCM declines eastward leading to two biogeographical provinces: one with diazotroph production and the other without diazotroph production.

Still from Processed Movie of Zonal Jets

NASA Technical Reports Server (NTRS)

2000-01-01

This image is one frame from a movie clip of cloud motions on Jupiter, from the side of the planet opposite to the Great Red Spot. It was taken in the first week of October 2000 by the narrow-angle camera on NASA's Cassini spacecraft, with a blue filter.

A white oval visible in the lower left is the remains of a historic merger that began several years ago, when three white oval storms that had existed for 60 years merged into two, then one. Like the Great Red Spot, it is a high-pressure center in the southern hemisphere, but only half as large. The color difference between the white oval and the Red Spot is not well understood, but it is undoubtedly related to the updrafts and downdrafts that carry chemicals to different heights in the two structures.

The region shown reaches from 50 degrees north to 50 degrees south of Jupiter's equator, and extends 100 degrees east-to-west, about one-quarter of Jupiter's circumference. The smallest features are about 500 kilometers (about 300 miles) across.

Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.

Stability of barotropic vortex strip on a rotating sphere

PubMed Central

Sohn, Sung-Ik; Kim, Sun-Chul

2018-01-01

We study the stability of a barotropic vortex strip on a rotating sphere, as a simple model of jet streams. The flow is approximated by a piecewise-continuous vorticity distribution by zonal bands of uniform vorticity. The linear stability analysis shows that the vortex strip becomes stable as the strip widens or the rotation speed increases. When the vorticity constants in the upper and the lower regions of the vortex strip have the same positive value, the inner flow region of the vortex strip becomes the most unstable. However, when the upper and the lower vorticity constants in the polar regions have different signs, a complex pattern of instability is found, depending on the wavenumber of perturbations, and interestingly, a boundary far away from the vortex strip can be unstable. We also compute the nonlinear evolution of the vortex strip on the rotating sphere and compare with the linear stability analysis. When the width of the vortex strip is small, we observe a good agreement in the growth rate of perturbation at an early time, and the eigenvector corresponding to the unstable eigenvalue coincides with the most unstable part of the flow. We demonstrate that a large structure of rolling-up vortex cores appears in the vortex strip after a long-time evolution. Furthermore, the geophysical relevance of the model to jet streams of Jupiter, Saturn and Earth is examined. PMID:29507524

Stability of barotropic vortex strip on a rotating sphere.

PubMed

Sohn, Sung-Ik; Sakajo, Takashi; Kim, Sun-Chul

2018-02-01

We study the stability of a barotropic vortex strip on a rotating sphere, as a simple model of jet streams. The flow is approximated by a piecewise-continuous vorticity distribution by zonal bands of uniform vorticity. The linear stability analysis shows that the vortex strip becomes stable as the strip widens or the rotation speed increases. When the vorticity constants in the upper and the lower regions of the vortex strip have the same positive value, the inner flow region of the vortex strip becomes the most unstable. However, when the upper and the lower vorticity constants in the polar regions have different signs, a complex pattern of instability is found, depending on the wavenumber of perturbations, and interestingly, a boundary far away from the vortex strip can be unstable. We also compute the nonlinear evolution of the vortex strip on the rotating sphere and compare with the linear stability analysis. When the width of the vortex strip is small, we observe a good agreement in the growth rate of perturbation at an early time, and the eigenvector corresponding to the unstable eigenvalue coincides with the most unstable part of the flow. We demonstrate that a large structure of rolling-up vortex cores appears in the vortex strip after a long-time evolution. Furthermore, the geophysical relevance of the model to jet streams of Jupiter, Saturn and Earth is examined.

The latitude dependence of the variance of zonally averaged quantities. [in polar meteorology with attention to geometrical effects of earth

NASA Technical Reports Server (NTRS)

North, G. R.; Bell, T. L.; Cahalan, R. F.; Moeng, F. J.

1982-01-01

Geometric characteristics of the spherical earth are shown to be responsible for the increase of variance with latitude of zonally averaged meteorological statistics. An analytic model is constructed to display the effect of a spherical geometry on zonal averages, employing a sphere labeled with radial unit vectors in a real, stochastic field expanded in complex spherical harmonics. The variance of a zonally averaged field is found to be expressible in terms of the spectrum of the vector field of the spherical harmonics. A maximum variance is then located at the poles, and the ratio of the variance to the zonally averaged grid-point variance, weighted by the cosine of the latitude, yields the zonal correlation typical of the latitude. An example is provided for the 500 mb level in the Northern Hemisphere compared to 15 years of data. Variance is determined to increase north of 60 deg latitude.

Generation of zonal flows by electrostatic drift waves in electron-positron-ion plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaladze, T. D.; I. Vekua Institute of Applied Mathematics, Tbilisi State University, 2 University Str., 0186 Tbilisi; Shad, M.

2010-02-15

Generation of large-scale zonal flows by comparatively small-scale electrostatic drift waves in electron-positron-ion plasmas is considered. The generation mechanism is based on the parametric excitation of convective cells by finite amplitude drift waves having arbitrary wavelengths (as compared with the ion Larmor radius of plasma ions at the plasma electron temperature). Temperature inhomogeneity of electrons and positrons is taken into account assuming ions to be cold. To describe the generation of zonal flow generalized Hasegawa-Mima equation containing both vector and two scalar (of different nature) nonlinearities is used. A set of coupled equations describing the nonlinear interaction of drift wavesmore » and zonal flows is deduced. Explicit expressions for the maximum growth rate as well as for the optimal spatial dimensions of the zonal flows are obtained. Enriched possibilities of zonal flow generation with different growth rates are revealed. The present theory can be used for interpretations of drift wave observations in laboratory and astrophysical plasmas.« less

The role of zonal flows in disc gravito-turbulence

NASA Astrophysics Data System (ADS)

Vanon, R.

2018-07-01

The work presented here focuses on the role of zonal flows in the self-sustenance of gravito-turbulence in accretion discs. The numerical analysis is conducted using a bespoke pseudo-spectral code in fully compressible, non-linear conditions. The disc in question, which is modelled using the shearing sheet approximation, is assumed to be self-gravitating, viscous, and thermally diffusive; a constant cooling time-scale is also considered. Zonal flows are found to emerge at the onset of gravito-turbulence and they remain closely linked to the turbulent state. A cycle of zonal flow formation and destruction is established, mediated by a slow mode instability (which allows zonal flows to grow) and a non-axisymmetric instability (which disrupts the zonal flow), which is found to repeat numerous times. It is in fact the disruptive action of the non-axisymmetric instability to form new leading and trailing shearing waves, allowing energy to be extracted from the background flow and ensuring the self-sustenance of the gravito-turbulent regime.

The role of zonal flows in disc gravito-turbulence

NASA Astrophysics Data System (ADS)

Vanon, R.

2018-04-01

The work presented here focuses on the role of zonal flows in the self-sustenance of gravito-turbulence in accretion discs. The numerical analysis is conducted using a bespoke pseudo-spectral code in fully compressible, non-linear conditions. The disc in question, which is modelled using the shearing sheet approximation, is assumed to be self-gravitating, viscous, and thermally diffusive; a constant cooling timescale is also considered. Zonal flows are found to emerge at the onset of gravito-turbulence and they remain closely linked to the turbulent state. A cycle of zonal flow formation and destruction is established, mediated by a slow mode instability (which allows zonal flows to grow) and a non-axisymmetric instability (which disrupts the zonal flow), which is found to repeat numerous times. It is in fact the disruptive action of the non-axisymmetric instability to form new leading and trailing shearing waves, allowing energy to be extracted from the background flow and ensuring the self-sustenance of the gravito-turbulent regime.

Faster paleospin and deep-seated uncompensated mass as possible explanations for Ceres' present-day shape and gravity

NASA Astrophysics Data System (ADS)

Mao, Xiaochen; McKinnon, William B.

2018-01-01

We show that Ceres' measured degree-2 zonal gravity, J2, is smaller by about 10% than that derived assuming Ceres' rotational flattening, as measured by Dawn, is hydrostatic. Irrespective of Ceres' radial density variation, as long as its internal structure is hydrostatic the J2 predicted from the shape model is consistently larger than measured. As an explanation, we suggest that Ceres' current shape may be a fossil remnant of faster rotation in the geologic past. We propose that up to ∼7% of Ceres' previous spin angular momentum has been removed by dynamic perturbations such as a random walk due to impacts or a loss of satellite that slowed Ceres spin as it tidally evolved outward. As an alternative, we also consider a formal degree-2 admittance solution, from which we infer a range of possible non-hydrostatic contributions to J2 from uncompensated, deep-seated density anomalies. We show that such density anomalies could be due to low order convection or upwelling. The normalized moments-of-inertia derived for the two explanations - faster paleospin and deep-seated density anomalies - range between 0.353 ± 0.009 and 0.375 ± 0.001 for a spherically equivalent Ceres, which can be used as constraints on more complex Ceres interior models.

Role of zonal flows in trapped electron mode turbulence through nonlinear gyrokinetic particle and continuum simulationa)

NASA Astrophysics Data System (ADS)

Ernst, D. R.; Lang, J.; Nevins, W. M.; Hoffman, M.; Chen, Y.; Dorland, W.; Parker, S.

2009-05-01

Trapped electron mode (TEM) turbulence exhibits a rich variety of collisional and zonal flow physics. This work explores the parametric variation of zonal flows and underlying mechanisms through a series of linear and nonlinear gyrokinetic simulations, using both particle-in-cell and continuum methods. A new stability diagram for electron modes is presented, identifying a critical boundary at ηe=1, separating long and short wavelength TEMs. A novel parity test is used to separate TEMs from electron temperature gradient driven modes. A nonlinear scan of ηe reveals fine scale structure for ηe≳1, consistent with linear expectation. For ηe<1, zonal flows are the dominant saturation mechanism, and TEM transport is insensitive to ηe. For ηe>1, zonal flows are weak, and TEM transport falls inversely with a power law in ηe. The role of zonal flows appears to be connected to linear stability properties. Particle and continuum methods are compared in detail over a range of ηe=d ln Te/d ln ne values from zero to five. Linear growth rate spectra, transport fluxes, fluctuation wavelength spectra, zonal flow shearing spectra, and correlation lengths and times are in close agreement. In addition to identifying the critical parameter ηe for TEM zonal flows, this paper takes a challenging step in code verification, directly comparing very different methods of simulating simultaneous kinetic electron and ion dynamics in TEM turbulence.

SPI Conformance Gel Applications in Geothermal Zonal Isolation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burns, Lyle

Zonal isolation in geothermal injection and producing wells is important while drilling the wells when highly fractured geothermal zones are encountered and there is a need to keep the fluids from interfering with the drilling operation. Department of Energy’s (DOE) Energy Efficiency and Renewable Energy (EERE) objectives are to advance technologies to make it more cost effective to develop, produce, and monitor geothermal reservoirs and produce geothermal energy. Thus, zonal isolation is critical to well cost, reservoir evaluation and operations. Traditional cementing off of the lost circulation or thief zones during drilling is often done to stem the drilling mudmore » losses. This is an expensive and generally unsuccessful technique losing the potential of the remaining fracture system. Selective placement of strong SPI gels into only the offending fractures can maintain and even improve operational efficiency and resource life. The SPI gel system is a unique silicate based gel system that offers a promising solution to thief zones and conformance problems with water and CO2 floods and potentially geothermal operations. This gel system remains a low viscosity fluid until an initiator (either internal such as an additive or external such as CO2) triggers gelation. This is a clear improvement over current mechanical methods of using packers, plugs, liners and cementing technologies that often severely damage the highly fractured area that is isolated. In the SPI gels, the initiator sets up the fluid into a water-like (not a precipitate) gel and when the isolated zone needs to be reopened, the SPI gel may be removed with an alkaline solution without formation damage occurring. In addition, the SPI gel in commercial quantities is expected to be less expensive than competing mechanical systems and has unique deep placement possibilities. This project seeks to improve upon the SPI gel integrity by modifying the various components to impart temperature stability for use in geothermal.« less

Improved Estimates of Clear Sky Longwave Flux and Application to the Tropical Greenhouse Effect

NASA Technical Reports Server (NTRS)

Collins, W. D.

1997-01-01

The first objective of this investigation is to eliminate the clear-sky offset introduced by the scene-identification procedures developed for the Earth Radiation Budget Experiment (ERBE). Estimates of this systematic bias range from 10 to as high as 30 W/sq m. The initial version of the ScaRaB data is being processed with the original ERBE algorithm. Since the ERBE procedure for scene identification is based upon zonal flux averages, clear scenes with longwave emission well below the zonal mean value are mistakenly classified as cloudy. The erroneous classification is more frequent in regions with deep convection and enhanced mid- and upper-tropospheric humidity. We will develop scene identification parameters with zonal and/or time dependence to reduce or eliminate the bias in the clear- sky data. The modified scene identification procedure could be used for the ScaRaB-specific version of the Earth-radiation products. The second objective is to investigate changes in the clear-sky Outgoing Longwave Radiation (OLR) associated with decadal variations in the tropical and subtropical climate. There is considerable evidence for a shift in the climate state starting in approximately 1977. The shift is accompanied by higher SSTs in the equatorial Pacific, increased tropical convection, and higher values of atmospheric humidity. Other evidence indicates that the humidity in the tropical troposphere has been steadily increasing over the last 30 years. It is not known whether the atmospheric greenhouse effect has increased during this period in response to these changes in SST and precipitable water. We will investigate the decadal-scale fluctuations in the greenhouse effect using Nimbus-7, ERBE, and ScaRaB measurements spaning 1979 to the present. The data from the different satellites will be intercalibrated by comparison with model calculations based upon ship radiosonde observations. The fluxes calculated from the radiation model will also be used for validation of the ScaRaB fluxes.

The atmospheres of Saturn and Titan in the near-infrared: First results of Cassini/Vims

USGS Publications Warehouse

Baines, K.H.; Momary, T.W.; Buratti, B.J.; Matson, D.L.; Nelson, R.M.; Drossart, P.; Sicardy, B.; Formisano, V.; Bellucci, G.; Coradini, A.; Griffith, C.; Brown, R.H.; Bibring, J.-P.; Langevin, Y.; Capaccioni, F.; Cerroni, P.; Clark, R.N.; Combes, M.; Cruikshank, D.P.; Jaumann, R.; McCordt, T.B.; Mennella, V.; Nicholson, P.D.; Sotin, Christophe

2006-01-01

The wide spectral coverage and extensive spatial, temporal, and phase-angle mapping capabilities of the Visual Infrared Mapping Spectrometer (VIMS) onboard the Cassini-Huygens Orbiter are producing fundamental new insights into the nature of the atmospheres of Saturn and Titan. For both bodies, VIMS maps over time and solar phase angles provide information for a multitude of atmospheric constituents and aerosol layers, providing new insights into atmospheric structure and dynamical and chemical processes. For Saturn, salient early results include evidence for phosphine depletion in relatively dark and less cloudy belts at temperate and mid-latitudes compared to the relatively bright and cloudier Equatorial Region, consistent with traditional theories of belts being regions of relative downwelling. Additional Saturn results include (1) the mapping of enhanced trace gas absorptions at the south pole, and (2) the first high phase-angle, high-spatial-resolution imagery of CH4 fluorescence. An additional fundamental new result is the first nighttime near-infrared mapping of Saturn, clearly showing discrete meteorological features relatively deep in the atmosphere beneath the planet's sunlit haze and cloud layers, thus revealing a new dynamical regime at depth where vertical dynamics is relatively more important than zonal dynamics in determining cloud morphology. Zonal wind measurements at deeper levels than previously available are achieved by tracking these features over multiple days, thereby providing measurements of zonal wind shears within Saturn's troposphere when compared to cloudtop movements measured in reflected sunlight. For Titan, initial results include (1) the first detection and mapping of thermal emission spectra of CO, CO2, and CH3D on Titan's nightside limb, (2) the mapping of CH4 fluorescence over the dayside bright limb, extending to ??? 750 km altitude, (3) wind measurements of ???0.5 ms-1, favoring prograde, from the movement of a persistent (multiple months) south polar cloud near 88??S latitude, and (4) the imaging of two transient mid-southern-latitude cloud features. ?? Springer Science+Business Media, Inc. 2006.

Saturn's North Polar Vortex Revealed by Cassini/VIMS: Zonal Wind Structure and Constraints on Cloud Distributions

NASA Astrophysics Data System (ADS)

Baines, Kevin H.; Momary, T. W.; Fletcher, L. N.; Buratti, B. J.; Roos-Serote, M.; Showman, A. P.; Brown, R. H.; Clark, R. N.; Nicholson, P. D.

2008-09-01

We present the first high-spatial resolution, near-nadir imagery and movies of Saturn's north polar region that reveal the wind structure of a north polar vortex. Obtained by Cassini/VIMS on June 15, 2008 from high over Saturn's polar region (sub-spacecraft latitude of 65 degrees N. lat) at an altitude of 0.42 million km during the long polar night, these 210-per-pixel images of the polar region north of 73 degrees N. latitude show several concentric cloud rings and hundreds of individual cloud features in silhouette against the 5-micron background thermal glow of Saturn's deep atmosphere. In contrast to the clear eye of the south polar vortex, the north polar vortex sports a central cloud feature about 650-km in diameter. Zonal winds reach a maximum of 150 m/s near 88 degrees N. latitude (planetocentric) - comparable to the south polar vortex maximum of 190 m/s near 88 degrees S. latitude - and fall off nearly monotonically to 10 m/s near 80 degrees N. latitude. At slightly greater distance from the pole, inside the north polar hexagon in the 75-77 degree N. latitude region, zonal winds increase dramatically to 130 m/s, as silhouetted clouds are seen speeding aroud the "race track” of the hexagonal feature. VIMS 5-micron thermal observations over a 1.6-year period from October 29, 2006 to June 15, 2008 are consistent with the polar hexagon structure itself remaining fixed in the Voyager-era radio rotation rate (Desch and Kaiser, Geophys. Res. Lett, 8, 253-256, 1981) to within an accuracy of 3 seconds per rotational period. This agrees with the stationary nature of the wave in this rotation system found by Godfrey (Icarus 76, 335-356, 1988), but is inconsistent with rotation rates found during the current Cassini era.

BROADBAND JET EMISSION IN YOUNG AND POWERFUL RADIO SOURCES: THE CASE OF THE COMPACT STEEP SPECTRUM QUASAR 3C 186

DOE Office of Scientific and Technical Information (OSTI.GOV)

Migliori, Giulia; Siemiginowska, Aneta; Celotti, Annalisa, E-mail: migliori@cfa.harvard.edu

2012-04-20

We present the X-ray analysis of a deep ({approx}200 ks) Chandra observation of the compact steep spectrum radio-loud quasar 3C 186 (z = 1.06) and investigate the contribution of the unresolved radio jet to the total X-ray emission. The spectral analysis is not conclusive on the origin of the bulk of the X-ray emission. In order to examine the jet contribution to the X-ray flux, we model the quasar spectral energy distribution, adopting several scenarios for the jet emission. For the values of the main physical parameters favored by the observables, a dominant role of the jet emission in themore » X-ray band is ruled out when a single-zone (leptonic) scenario is adopted, even including the contribution of the external photon fields as seed photons for inverse Compton emission. We then consider a structured jet, with the blazar component that-although not directly visible in the X-ray band-provides an intense field of seed synchrotron photons Compton-scattered by electrons in a mildly relativistic knot. In this case, the whole X-ray emission can be accounted for if we assume a blazar luminosity within the range observed from flat spectrum radio quasars. The X-ray radiative efficiency of such a (structured) jet is intimately related to the presence of a complex velocity structure. The jet emission can provide a significant contribution in X-rays if it decelerates within the host galaxy on kiloparsec scales. We discuss the implications of this model in terms of jet dynamics and interaction with the ambient medium.« less

Two- and three-dimensional natural and mixed convection simulation using modular zonal models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wurtz, E.; Nataf, J.M.; Winkelmann, F.

We demonstrate the use of the zonal model approach, which is a simplified method for calculating natural and mixed convection in rooms. Zonal models use a coarse grid and use balance equations, state equations, hydrostatic pressure drop equations and power law equations of the form {ital m} = {ital C}{Delta}{sup {ital n}}. The advantage of the zonal approach and its modular implementation are discussed. The zonal model resolution of nonlinear equation systems is demonstrated for three cases: a 2-D room, a 3-D room and a pair of 3-D rooms separated by a partition with an opening. A sensitivity analysis withmore » respect to physical parameters and grid coarseness is presented. Results are compared to computational fluid dynamics (CFD) calculations and experimental data.« less

Rossby Wave Propagation into the Northern Hemisphere Stratosphere: The Role of Zonal Phase Speed

NASA Astrophysics Data System (ADS)

Domeisen, Daniela I. V.; Martius, Olivia; Jiménez-Esteve, Bernat

2018-02-01

Sudden stratospheric warming (SSW) events are to a dominant part induced by upward propagating planetary waves. While theory predicts that the zonal phase speed of a tropospheric wave forcing affects wave propagation into the stratosphere, its relevance for SSW events has so far not been considered. This study shows in a linear wave diagnostic and in reanalysis data that phase speeds tend eastward as waves propagate upward, indicating that the stratosphere preselects eastward phase speeds for propagation, especially for zonal wave number 2. This also affects SSW events: Split SSW events tend to be preceded by anomalously eastward zonal phase speeds. Zonal phase speed may indeed explain part of the increased wave flux observed during the preconditioning of SSW events, as, for example, for the record 2009 SSW event.

Stratospheric mountain wave attenuation in positive and negative ambient wind shear

NASA Astrophysics Data System (ADS)

Kruse, C. G.; Smith, R. B.

2016-12-01

Recently, much has been learned about the vertical propagation and attenuation of mountain waves launched by the Southern Alps of New Zealand (NZ) from the Deep Propagating Gravity Wave Experiment (DEEPWAVE) field campaign. Over NZ, approximately half of mountain wave events are strongly attenuated in a lower-stratospheric "valve layer," defined as a layer of reduced wind with no critical levels. Within a valve layer, negative wind shear causes mountain waves steepen and attenuate, with the amount of transmitted momentum flux controlled by the minimum wind speed within the layer. The other half of wave events are deep (propagating to 35+ km), usually with positive wind shear. Within these deep events, increasing amplitude with decreasing density causes mountain waves to attenuate gradually (after spatial/temporal averaging). Global reanalyses indicate that this valve layer is a climatological feature in the wintertime mid-latitudes above the subtropical jet, while deep events and gradual attenuation occur over higher latitudes below the polar stratospheric jet. The local physics of mountain wave attenuation in positive and negative ambient wind shear are investigated using realistic winter-long (JJA) 6-km resolution Weather Research and Forecasting (WRF) model simulations over the Andes. Attention is given to the spatiotemporal variability of wave attenuation and the various factors driving this variability (e.g. variability in wave generation, ambient conditions at attenuation level, inherent wave-induced instabilities). Mesoscale potential vorticity generation is used as an indicator of wave attenuation. Additionally, regionally integrated wave momentum flux and gravity wave drag (GWD) within WRF are quantified and compared with parameterized quantities in the MERRA1 and 2 reanalyses.

Publications of the Jet Propulsion Laboratory 1976

NASA Technical Reports Server (NTRS)

1977-01-01

The formalized technical reporting, released January through December 1975, that resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory is described and indexed. The following classes of publications are included: (1) technical reports; (2) technical memorandums; (3) articles from bi-monthly Deep Space Network (DSN) progress report; (4) special publications; and (5) articles published in the open literature. The publications are indexed by: (1) author, (2) subject, and (3) publication type and number. A descriptive entry appears under the name of each author of each publication; an abstract is included with the entry for the primary (first-listed) author. Unless designated otherwise, all publications listed are unclassified.

Publications of the Jet Propulsion Laboratory, 1992

NASA Technical Reports Server (NTRS)

1994-01-01

JPL Bibliography 39-33 describes and indexes by primary author the externally distributed technical reporting, released during calendar year 1992, that resulted from scientific and engineering work performed or managed by the Jet Propulsion Laboratory. Three classes of publications are included: (1) JPL Publication (92-series) in which the information is complete for a specific accomplishment; (2) articles from the quarterly Telecommunications and Data Acquisition (TDA) Progress Report (42-series) (each collection of articles in this class of publication presents a periodic survey of current accomplishments by the Deep Space Network as well as other developments in Earth-based radio technology); and (3) articles published in the open literature.

Gigantic Jet Environments: A Meteorological Evaluation Using Reanalysis Data Sets

NASA Astrophysics Data System (ADS)

Splitt, M. E.; Lazarus, S. M.

2017-12-01

The meteorological conditions of gigantic jet (GJ) producing thunderstorms tend to be connected to maritime tropical environments. In particular, they have an affinity toward tropical disturbances including those with moderate values of upper tropospheric environmental wind shear. Wind shear related effects (including turbulence) in association with deep convection in these environments have been proposed as mechanisms for the arrangement of GJ favorable charge structures. This study focuses on a climatological evaluation in an effort to assess whether the proposed ingredients are consistent with observed GJ event regions. The Climate System Forecast System - Version 2 (CFSR V2) is used here to test for the proposed GJ conditions.

Environmental projects. Volume 7: Environmental resources document

NASA Technical Reports Server (NTRS)

Kushner, Len; Kroll, Glenn

1988-01-01

The Goldstone Deep Space Communications Complex (GDSCC) in Barstow, California, is part of the NASA Deep Space Network, one of the world's largest and most sensitive scientific telecommunications and radio navigation networks. Goldstone is managed, directed and operated by the Jet Propulsion Laboratory of Pasadena, California. The GDSCC includes five distinct operational sites: Echo, Venus, Mars, Apollo, and Mojave Base. Within each site is a Deep Space Station (DPS), consisting of a large dish antenna and its support facilities. As required by NASA directives concerning the implementation of the National Environmental Policy Act, each NASA field installation is to publish an Environmental Resources Document describing the current environment at the installation, including any adverse effects that NASA operations may have on the local environment.

On the Pathways of the Return Flow of the Meridional Overturning Circulation in the Tropical Atlantic

NASA Technical Reports Server (NTRS)

Jochum, Markus

2002-01-01

A numerical model of the tropical Atlantic ocean is used to investigate the upper layer pathways of the Meridional Overturning Circulation (MOC) in the tropical Atlantic. The main focus of this thesis is on those parts of the tropical circulation that are thought to be important for the MOC return flow, but whose dynamics have not been understood yet. It is shown how the particular structure of the tropical gyre and the MOO act to inhibit the flow of North Atlantic water into the equatorial thermocline. As a result, the upper layers of the tropical Atlantic are mainly fed by water from the South Atlantic. The processes that carry the South Atlantic water across the tropical Atlantic into the North Atlantic as part of the MOO are described here, and three processes that were hitherto not understood are explained as follows: The North Brazil Current rings are created as the result of the reflection of Rossby waves at the South American coast. These Rossby waves are generated by the barotropically unstable North Equatorial Countercurrent. The deep structure of the rings can be explained by merger of the wave's anticyclones with the deeper intermediate eddies that are generated as the intermediate western boundary current crosses the equator. The bands of strong zonal velocity in intermediate depths along the equator have hitherto been explained as intermediate currents. Here, an alternative interpretation of the observations is offered: The Eulerian mean flow along the equator is negligible and the observations are the signature of strong seasonal Rossby waves. The previous interpretation of the observations can then be explained as aliasing of the tropical wave field. The Tsuchyia Jets are driven by the Eliassen-Palm flux of the tropical instability waves. The equatorial current system with its strong shears is unstable and generates tropical instability waves.

Disturbance zonal and vertical plasma drifts in the Peruvian sector during solar minimum phases

NASA Astrophysics Data System (ADS)

Santos, A. M.; Abdu, M. A.; Souza, J. R.; Sobral, J. H. A.; Batista, I. S.

2016-03-01

In the present work, we investigate the behavior of the equatorial F region zonal plasma drifts over the Peruvian region under magnetically disturbed conditions during two solar minimum epochs, one of them being the recent prolonged solar activity minimum. The study utilizes the vertical and zonal components of the plasma drifts measured by the Jicamarca (11.95°S; 76.87°W) incoherent scatter radar during two events that occurred on 10 April 1997 and 24 June 2008 and model calculation of the zonal drift in a realistic ionosphere simulated by the Sheffield University Plasmasphere-Ionosphere Model-INPE. Two main points are focused: (1) the connection between electric fields and plasma drifts under prompt penetration electric field during a disturbed periods and (2) anomalous behavior of daytime zonal drift in the absence of any magnetic storm. A perfect anticorrelation between vertical and zonal drifts was observed during the night and in the initial and growth phases of the magnetic storm. For the first time, based on a realistic low-latitude ionosphere, we will show, on a detailed quantitative basis, that this anticorrelation is driven mainly by a vertical Hall electric field induced by the primary zonal electric field in the presence of an enhanced nighttime E region ionization. It is shown that an increase in the field line-integrated Hall-to-Pedersen conductivity ratio (∑H/∑P), which can arise from precipitation of energetic particles in the region of the South American Magnetic Anomaly, is capable of explaining the observed anticorrelation between the vertical and zonal plasma drifts. Evidence for the particle ionization is provided from the occurrence of anomalous sporadic E layers over the low-latitude station, Cachoeira Paulista (22.67°S; 44.9°W)—Brazil. It will also be shown that the zonal plasma drift reversal to eastward in the afternoon two hours earlier than its reference quiet time pattern is possibly caused by weakening of the zonal wind system during the prolonged solar minimum period.

Middle and long-term prediction of UT1-UTC based on combination of Gray Model and Autoregressive Integrated Moving Average

NASA Astrophysics Data System (ADS)

Jia, Song; Xu, Tian-he; Sun, Zhang-zhen; Li, Jia-jing

2017-02-01

UT1-UTC is an important part of the Earth Orientation Parameters (EOP). The high-precision predictions of UT1-UTC play a key role in practical applications of deep space exploration, spacecraft tracking and satellite navigation and positioning. In this paper, a new prediction method with combination of Gray Model (GM(1, 1)) and Autoregressive Integrated Moving Average (ARIMA) is developed. The main idea is as following. Firstly, the UT1-UTC data are preprocessed by removing the leap second and Earth's zonal harmonic tidal to get UT1R-TAI data. Periodic terms are estimated and removed by the least square to get UT2R-TAI. Then the linear terms of UT2R-TAI data are modeled by the GM(1, 1), and the residual terms are modeled by the ARIMA. Finally, the UT2R-TAI prediction can be performed based on the combined model of GM(1, 1) and ARIMA, and the UT1-UTC predictions are obtained by adding the corresponding periodic terms, leap second correction and the Earth's zonal harmonic tidal correction. The results show that the proposed model can be used to predict UT1-UTC effectively with higher middle and long-term (from 32 to 360 days) accuracy than those of LS + AR, LS + MAR and WLS + MAR.

A Thermodynamic, kinematic and microphysical analysis of a jet and gigantic jet-producing Florida thunderstorm

NASA Astrophysics Data System (ADS)

Lazarus, S. M.; Splitt, M. E.; Brownlee, James; Spiva, Nicholas; Liu, Ningyu

2015-08-01

This paper presents a meteorological analysis of a storm that produced two jets, four gigantic jets (GJ), and a starter, which were observed by two radars as well as the Kennedy Space Center 4-Dimensional Lightning Surveillance System on 3 August 2013 in Central Florida. The work is the first application of dual polarization data to a jet-producing storm and is the fifth case related to a tropical disturbance. The storm environment is consistent with the moist tropical paradigm that characterizes about three quarters of the surface and aircraft observed jet and GJ events. The most unstable (MU) convective available potential energy is not unusual for Florida summer convection and is below the climatological mean for these events. An unusual speed shear layer is located near the storm equilibrium level (EL) and the storm exhibits a tilted structure with CGs displaced upshear. The turbulence, as measured by the eddy dissipation rate, is extreme near the storm top during the event window, consistent with the GJ mixing hypothesis. The individual events are collocated with, and track along, the center axis of the divergent outflow at the EL and occur within the region of the coldest GOES IR temperatures—placing the events within the overshoot. The dual polarization data indicate a deep graupel column, extending above the mixed phase layer, to a 13 km altitude.

Flows of Antarctic bottom water through fractures in the southern part of the North Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Morozov, E. G.; Tarakanov, R. Yu.; Makarenko, N. I.

2015-11-01

We study the flows of bottom waters of the Antarctic origin in deep fracture zones of the southern part of the North Mid-Atlantic Ridge. In the autumn of 2014, an expedition onboard the RV Akademik Sergey Vavilov carried out measurements of current velocities and thermohaline properties of bottom water in several quasi-zonal fractures in the southern part of the Northern Mid-Atlantic Ridge, which connect the deep basins of the West and East Atlantic, the Vema Fracture Zone (FZ) (10°50' N) and a group of sub-equatorial fractures: Doldrums (8°15' N), Vernadsky (7°40' N), and a nameless fracture at 7°30' N. The estimates of bottom water (θ < 2.0°C) transport through this group based on measurements from 2014 are approximately 0.28 Sv (1 Sv = 106 m3/s), which is close to 25% of the transport estimate through the Vema FZ (1.20 Sv) obtained in the same expedition. The coldest bottom water temperatures among the investigated fractures were recorded in the Vema FZ.

Coupling of jet and accretion activity in the active galaxy NGC 1052

NASA Astrophysics Data System (ADS)

Boeck, Moritz; Kadler, Matthias; Ros, Eduardo; Weaver, Kimberly; Wilms, Joern; Brenneman, Laura; Angelakis, Emmanouil

The radio loud galaxy NGC 1052 has been monitored for the past fifteen years with Very Long Baseline Interferometry (VLBI) observations and has been the target of an intense multiwave-length monitoring campaign since 2005. This provides an excellent dataset for analyzing the relationship between properties of the relativistic jet and the accretion disk in active galactic nuclei. Components in the jet are tracked and the ejection times of new components are deter-mined. The analysis of the radio variability is complemented by the study of X-ray observations allowing us to draw conclusions on the accretion activity. The X-ray variability on weekly and monthly time scales is monitored with the Rossi X-ray Timing Explorer, whereas deep XMM-Newton and Suzaku observations provide spectra showing a broad Fe Kα line, whose variability can provide a particularly valuable probe of the inner accretion flow.

Analysis of solute-protein interactions and solute-solute competition by zonal elution affinity chromatography.

PubMed

Tao, Pingyang; Poddar, Saumen; Sun, Zuchen; Hage, David S; Chen, Jianzhong

2018-02-02

Many biological processes involve solute-protein interactions and solute-solute competition for protein binding. One method that has been developed to examine these interactions is zonal elution affinity chromatography. This review discusses the theory and principles of zonal elution affinity chromatography, along with its general applications. Examples of applications that are examined include the use of this method to estimate the relative extent of solute-protein binding, to examine solute-solute competition and displacement from proteins, and to measure the strength of these interactions. It is also shown how zonal elution affinity chromatography can be used in solvent and temperature studies and to characterize the binding sites for solutes on proteins. In addition, several alternative applications of zonal elution affinity chromatography are discussed, which include the analysis of binding by a solute with a soluble binding agent and studies of allosteric effects. Other recent applications that are considered are the combined use of immunoextraction and zonal elution for drug-protein binding studies, and binding studies that are based on immobilized receptors or small targets. Copyright © 2018 Elsevier Inc. All rights reserved.

Effect of external plasma flows on the interaction between turbulence and convective cells

NASA Astrophysics Data System (ADS)

Uzawa, Ken; Li, Jiquan

2005-10-01

It is widely recognized that large scale structures, such as zonal flows, streamers and also long wavelength Kelvin-Helmholtz modes are nonlinearly generated from maternal turbulence through modulational instability process and play a crucial role in regulating the transport in tokamaks. In order to control the transport, it is desirable to control such structures and/or modulational process. One of control parameters may be mean flow which intrinsically exists in tokamak plasmas. Besides the direct influence on the transport through vortex decorrelation, the mean flow may indirectly change the zonal flow generation by acting on the modulational process itself. In this work, we theoretically investigate the characteristics of zonal flow generation due to the electron temperature gradient (ETG) turbulence in the presence of long wavelength ITG driven zonal flow. This was done by extending our previous modulational analyses[1]. We have numerically analyzed the influence of mean flow on zonal flow generation. The main result is that the zonal flow generation is suppressed by the presence of the mean flow. [1]J. Li, Y. Kishimoto, Physics of Plasmas, 9, 1241 (2002)

The Role of Monsoon-Like Zonally Asymmetric Heating in Interhemispheric Transport

NASA Technical Reports Server (NTRS)

Chen, Gang; Orbe, Clara; Waugh, Darryn

2017-01-01

While the importance of the seasonal migration of the zonally averaged Hadley circulation on interhemispheric transport of trace gases has been recognized, few studies have examined the role of the zonally asymmetric monsoonal circulation. This study investigates the role of monsoon-like zonally asymmetric heating on interhemispheric transport using a dry atmospheric model that is forced by idealized Newtonian relaxation to a prescribed radiative equilibrium temperature. When only the seasonal cycle of zonally symmetric heating is considered, the mean age of air in the Southern Hemisphere since last contact with the Northern Hemisphere midlatitude boundary layer, is much larger than the observations. The introduction of monsoon-like zonally asymmetric heating not only reduces the mean age of tropospheric air to more realistic values, but also produces an upper-tropospheric cross-equatorial transport pathway in boreal summer that resembles the transport pathway simulated in the NASA Global Modeling Initiative (GMI) Chemistry Transport Model driven with MERRA meteorological fields. These results highlight the monsoon-induced eddy circulation plays an important role in the interhemispheric transport of long-lived chemical constituents.

Diffractive hard photoproduction at HERA and evidence for the gluon content of the pomeron

NASA Astrophysics Data System (ADS)

Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Repond, J.; Stanek, R.; Talaga, R. L.; Zhang, H.; Ayad, R.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Polini, A.; Sartorelli, G.; Timellini, R.; Zamora Garcia, Y.; Zichichi, A.; Bargende, A.; Crittenden, J.; Desch, K.; Diekmann, B.; Doeker, T.; Eckert, M.; Feld, L.; Frey, A.; Geerts, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mari, S. M.; Mengel, S.; Mollen, J.; Paul, E.; Pfeiffer, M.; Rembser, Ch; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Dyce, N.; Foster, B.; George, S.; Gilmore, R.; Heath, G. P.; Heath, H. F.; Llewellyn, T. J.; Morgado, C. J. S.; Norman, D. J. P.; O'Mara, J. A.; Tapper, R. J.; Wilson, S. S.; Yoshida, R.; Rau, R. R.; Arneodo, M.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Bernstein, A.; Caldwell, A.; Cartiglia, N.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Kotański, A.; Przybycień, M.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Coldewey, C.; Deppe, O.; Desler, K.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Gutjahr, B.; Haas, T.; Hain, W.; Hasell, D.; Heßling, H.; Iga, Y.; Johnson, K.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Köpke, L.; Kötz, U.; Kowalski, H.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mainusch, J.; Mańczak, O.; Monteiro, T.; Ng, J. S. T.; Nickel, S.; Notz, D.; Ohrenberg, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Stiliaris, E.; Surrow, B.; Voß, T.; Westphal, D.; Wolf, G.; Youngman, C.; Zeuner, W.; Zhou, J. F.; Grabosch, H. J.; Kharchilava, A.; Leich, A.; Mattingly, M. C. K.; Meyer, A.; Schlenstedt, S.; Wulff, N.; Barbagli, G.; Pelfer, P.; Anzivino, G.; Maccarrone, G.; De Pasquale, S.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Freidhof, A.; Söldner-Rembold, S.; Schroeder, J.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Fleck, J. I.; Saxon, D. H.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Neumann, T.; Sinkus, R.; Wick, K.; Badura, E.; Burow, B. D.; Hagge, L.; Lohrmann, E.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Bruemmer, N.; Butterworth, I.; Gallo, E.; Harris, V. L.; Hung, B. Y. H.; Long, K. R.; Miller, D. B.; Morawitz, P. P. O.; Prinias, A.; Sedgbeer, J. K.; Whitfield, A. F.; Mallik, U.; McCliment, E.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; An, S. H.; Hong, S. M.; Nam, S. W.; Park, S. K.; Suh, M. H.; Yon, S. H.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Cases, G.; Fernandez, J. P.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martinez, M.; del Peso, J.; Puga, J.; Terron, J.; de Trocóniz, J. F.; Smith, G. R.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; St. Laurent, M.; Ullmann, R.; Zacek, G.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Yu. A.; Kobrin, V. D.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Botje, M.; Chlebana, F.; Dake, A.; Engelen, J.; de Kamps, M.; Kooijman, P.; Kruse, A.; Tiecke, H.; Verkerke, W.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Honscheid, K.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Park, I. H.; Romanowski, T. A.; Seidlein, R.; Bailey, D. S.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Lindemann, L.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Wilson, F. F.; Yip, T.; Abbiendi, G.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Butterworth, J. M.; Feild, R. G.; Oh, B. Y.; Whitmore, J. J.; D'Agostini, G.; Marini, G.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Prytz, K.; Shah, T. P.; Short, T. L.; Barberis, E.; Dubbs, T.; Heusch, C.; Van Hook, M.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Biltzinger, J.; Seifert, R. J.; Schwarzer, O.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Levy, A.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kuze, M.; Mine, S.; Nagasawa, Y.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Nakamitsu, Y.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Brkic, M.; Crombie, M. B.; Gingrich, D. M.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sampson, C. R.; Teuscher, R. J.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Blankenship, K.; Lu, B.; Mo, L. W.; Bogusz, W.; Charchuła, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprazak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Eisenberg, Y.; Karshon, U.; Revel, D.; Zer-Zion, D.; Ali, I.; Badgett, W. F.; Behrens, B.; Dasu, S.; Fordham, C.; Foudas, C.; Goussiou, A.; Loveless, R. J.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Tsurugai, T.; Bhadra, S.; Cardy, M. L.; Fagerstroem, C.-P.; Frisken, W. R.; Furutani, K. M.; Khakzad, M.; Schmidke, W. B.; ZEUS Collaboration

1995-02-01

Inclusive jet cross sections for events with a large rapidity gap with respect to the proton direction from the reaction ep → jet + X with quasi-real photons have been measured with the ZEUS detector. The cross sections refer to jets with transverse energies ETjet > 8 GeV. The data show the characteristics of a diffractive process mediated by pomeron exchange. Assuming that the events are due to the exchange of a pomeron with partonic structure, the quark and gluon content of the pomeron is probed at a scale ˜ ( ETjet) 2. A comparison of the measurements with model predictions based on QCD plus Regge phenomenology requires a contribution of partons with a hard momentum density in the pomeron. A combined analysis of the jet cross sections and recent ZEUS measurements of the diffractive structure function in deep inelastic scattering gives the first experimental evidence for the gluon content of the pomeron in diffractive hard scattering processes. The data indicate that between 30% and 80% of the momentum of the pomeron carried by partons is due to hard gluons.

Autonomous real-time detection of plumes and jets from moons and comets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagstaff, Kiri L.; Thompson, David R.; Bue, Brian D.

2014-10-10

Dynamic activity on the surface of distant moons, asteroids, and comets can manifest as jets or plumes. These phenomena provide information about the interior of the bodies and the forces (gravitation, radiation, thermal) they experience. Fast detection and follow-up study is imperative since the phenomena may be time-varying and because the observing window may be limited (e.g., during a flyby). We have developed an advanced method for real-time detection of plumes and jets using onboard analysis of the data as it is collected. In contrast to prior work, our technique is not restricted to plume detection from spherical bodies, makingmore » it relevant for irregularly shaped bodies such as comets. Further, our study analyzes raw data, the form in which it is available on board the spacecraft, rather than fully processed image products. In summary, we contribute a vital assessment of a technique that can be used on board tomorrow's deep space missions to detect, and respond quickly to, new occurrences of plumes and jets.« less

Influence of oxygen in atmospheric-pressure argon plasma jet on sterilization of Bacillus atrophaeous spores

NASA Astrophysics Data System (ADS)

Lim, Jin-Pyo; Uhm, Han S.; Li, Shou-Zhe

2007-09-01

A nonequilibrium Ar /O2 plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. The decimal reduction time (D values) of the Ar /O2 plasma jet at an exposure distance of 0.5-1.5cm ranges from 5 to 57s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

Antecedent Synoptic Environments Conducive to North American Polar/Subtropical Jet Superpositions

NASA Astrophysics Data System (ADS)

Winters, A. C.; Keyser, D.; Bosart, L. F.

2017-12-01

The atmosphere often exhibits a three-step pole-to-equator tropopause structure, with each break in the tropopause associated with a jet stream. The polar jet stream (PJ) typically resides in the break between the polar and subtropical tropopause and is positioned atop the strongly baroclinic, tropospheric-deep polar front around 50°N. The subtropical jet stream (STJ) resides in the break between the subtropical and the tropical tropopause and is situated on the poleward edge of the Hadley cell around 30°N. On occasion, the latitudinal separation between the PJ and the STJ can vanish, resulting in a vertical jet superposition. Prior case study work indicates that jet superpositions are often attended by a vigorous transverse vertical circulation that can directly impact the production of extreme weather over North America. Furthermore, this work suggests that there is considerable variability among antecedent environments conducive to the production of jet superpositions. These considerations motivate a comprehensive study to examine the synoptic-dynamic mechanisms that operate within the double-jet environment to produce North American jet superpositions. This study focuses on the identification of North American jet superposition events in the CFSR dataset during November-March 1979-2010. Superposition events will be classified into three characteristic types: "Polar Dominant" events will consist of events during which only the PJ is characterized by a substantial excursion from its climatological latitude band; "Subtropical Dominant" events will consist of events during which only the STJ is characterized by a substantial excursion from its climatological latitude band; and "Hybrid" events will consist of those events characterized by an excursion of both the PJ and STJ from their climatological latitude bands. Following their classification, frequency distributions of jet superpositions will be constructed to highlight the geographical locations most often associated with jet superpositions for each event type. PV inversion and composite analysis will also be performed on each event type in an effort to illustrate the antecedent environments and the dominant synoptic-dynamic mechanisms that favor the production of North American jet superpositions for each event type.

Fluid simulation of tokamak ion temperature gradient turbulence with zonal flow closure model

NASA Astrophysics Data System (ADS)

Yamagishi, Osamu; Sugama, Hideo

2016-03-01

Nonlinear fluid simulation of turbulence driven by ion temperature gradient modes in the tokamak fluxtube configuration is performed by combining two different closure models. One model is a gyrofluid model by Beer and Hammett [Phys. Plasmas 3, 4046 (1996)], and the other is a closure model to reproduce the kinetic zonal flow response [Sugama et al., Phys. Plasmas 14, 022502 (2007)]. By including the zonal flow closure, generation of zonal flows, significant reduction in energy transport, reproduction of the gyrokinetic transport level, and nonlinear upshift on the critical value of gradient scale length are observed.

Fluid simulation of tokamak ion temperature gradient turbulence with zonal flow closure model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamagishi, Osamu, E-mail: yamagisi@nifs.ac.jp; Sugama, Hideo

Nonlinear fluid simulation of turbulence driven by ion temperature gradient modes in the tokamak fluxtube configuration is performed by combining two different closure models. One model is a gyrofluid model by Beer and Hammett [Phys. Plasmas 3, 4046 (1996)], and the other is a closure model to reproduce the kinetic zonal flow response [Sugama et al., Phys. Plasmas 14, 022502 (2007)]. By including the zonal flow closure, generation of zonal flows, significant reduction in energy transport, reproduction of the gyrokinetic transport level, and nonlinear upshift on the critical value of gradient scale length are observed.

The Telecommunications and Data Acquisition Progress Report 42-123

NASA Technical Reports Server (NTRS)

Yuen, Joseph H. (Editor)

1995-01-01

The progress of research programs monitored by the Jet Propulsion Laboratory's Telecommunications and Mission Operations Directorate (TMOD) are presented in this quarterly document. Areas monitored include space communications, radio navigation, radio science, ground-based radio and radar astronomy, information systems, and all other communication and research technology activities for the Deep Space Network (DSN).

A comparison of the momentum budget in reanalysis datasets during sudden stratospheric warming events

NASA Astrophysics Data System (ADS)

Martineau, Patrick; Son, Seok-Woo; Taguchi, Masakazu; Butler, Amy H.

2018-05-01

The agreement between reanalysis datasets, in terms of the zonal-mean momentum budget, is evaluated during sudden stratospheric warming (SSW) events. It is revealed that there is a good agreement among datasets in the lower stratosphere and troposphere concerning zonal-mean zonal wind, but less so in the upper stratosphere. Forcing terms of the momentum equation are also relatively similar in the lower atmosphere, but their uncertainties are typically larger than uncertainties of the zonal-wind tendency. Similar to zonal-wind tendency, the agreement among forcing terms is degraded in the upper stratosphere. Discrepancies among reanalyses increase during the onset of SSW events, a period characterized by unusually large fluxes of planetary-scale waves from the troposphere to the stratosphere, and decrease substantially after the onset. While the largest uncertainties in the resolved terms of the momentum budget are found in the Coriolis torque, momentum flux convergence also presents a non-negligible spread among the reanalyses. Such a spread is reduced in the latest reanalysis products, decreasing the uncertainty of the momentum budget. It is also found that the uncertainties in the Coriolis torque depend on the strength of SSW events: the SSW events that exhibit the most intense deceleration of zonal-mean zonal wind are subject to larger discrepancies among reanalyses. These uncertainties in stratospheric circulation, however, are not communicated to the troposphere.

A study of the stability of Jovian winds from HST images: 1995 - 1998

NASA Astrophysics Data System (ADS)

Garcia-Melendo, E.; Sanchez-Lavega, A.

2000-10-01

The resolution of the best WFPC-2 HST Jupiter images was 200 kmpix-1, which is close to the maximum resolution obtained by the narrow angle cameras on board Voyager 1 and 2, 160 kmpix-1. This property of the best HST Jupiter imaging spanning a whole Jovian rotation, encouraged the use of correlation techniques to obtain a series of high resolution zonal wind profiles with a velocity data scatter similar to that obtained from Voyager images. This approach provided a unique opportunity to study the Jovian winds during a time span of 4 years, which is about 12 times longer than the 4 month lapse between the two Voyager flybys in 1979, 16 years later, and before the Cassini encounter at the end of 2000. A total of six series of wind profiles from October 5, 1995 to July 16, 1998, in the 410nm, 889nm, and 953nm bands were obtained with an average velocity scatter between 5 and 6 m/s. Jovian winds were also explored up to planetographic latitudes close to +80 degrees north and -70 degrees south. Results show the presence of two previously unknown jets over +60N and at least an additional one to the south of 60S degrees latitude. Wind profiles obtained at different wavelengths were also virtually indistinguishable, suggesting a negligible influence of a possible height effect. One of the most conspicuous results is the strong general stability displayed by the wind profile during the four year span, although the jet stream at 26S showed important alterations in shape. Comparing the HST wind profiles with the Voyager 2 wind profile obtained in violet light by S. Limaye (Icarus, Vol. 65, 335, 1986), slight latitude differences up to 1.5 degrees latitude are suggested for the location of some westerly and easterly jet streams, specially in the planet's northern hemisphere. Important changes also occurred in the eastward jets at 6S and 23N degrees of latitude. This work was supported by E. Duran Foundation and Gobierno Vasco PI 034/97.

KSC-98pc1177

NASA Image and Video Library

1998-09-29

KENNEDY SPACE CENTER, FLA. -- In the Payload Hazardous Servicing Facility, the media (below), dressed in "bunny" suits, learn about Deep Space 1 from Leslie Livesay (facing cameras), Deep Space 1 spacecraft manager from the Jet Propulsion Laboratory. In the background, KSC workers place insulating blankets on Deep Space 1. The first flight in NASA's New Millennium Program, Deep Space 1 is designed to validate 12 new technologies for scientific space missions of the next century. Onboard experiments include an ion propulsion engine and software that tracks celestial bodies so the spacecraft can make its own navigation decisions without the intervention of ground controllers. Deep Space 1 will complete most of its mission objectives within the first two months, but may also do a flyby of a near-Earth asteroid, 1992 KD, in July 1999. Deep Space 1 will be launched aboard a Boeing Delta 7326 rocket from Launch Pad 17A, Cape Canaveral Air Station, in October. Delta II rockets are medium capacity expendable launch vehicles derived from the Delta family of rockets built and launched since 1960. Since then there have been more than 245 Delta launches

HVAC modifications and computerized energy analysis for the Operations Support Building at the Mars Deep Space Station at Goldstone

NASA Technical Reports Server (NTRS)

Halperin, A.; Stelzmuller, P.

1986-01-01

The key heating, ventilation, and air-conditioning (HVAC) modifications implemented at the Mars Deep Space Station's Operation Support Building at Jet Propulsion Laboratories (JPL) in order to reduce energy consumption and decrease operating costs are described. An energy analysis comparison between the computer simulated model for the building and the actual meter data was presented. The measurement performance data showed that the cumulative energy savings was about 21% for the period 1979 to 1981. The deviation from simulated data to measurement performance data was only about 3%.

Composite and case study analyses of the large-scale environments associated with West Pacific Polar and subtropical vertical jet superposition events

NASA Astrophysics Data System (ADS)

Handlos, Zachary J.

Though considerable research attention has been devoted to examination of the Northern Hemispheric polar and subtropical jet streams, relatively little has been directed toward understanding the circumstances that conspire to produce the relatively rare vertical superposition of these usually separate features. This dissertation investigates the structure and evolution of large-scale environments associated with jet superposition events in the northwest Pacific. An objective identification scheme, using NCEP/NCAR Reanalysis 1 data, is employed to identify all jet superpositions in the west Pacific (30-40°N, 135-175°E) for boreal winters (DJF) between 1979/80 - 2009/10. The analysis reveals that environments conducive to west Pacific jet superposition share several large-scale features usually associated with East Asian Winter Monsoon (EAWM) northerly cold surges, including the presence of an enhanced Hadley Cell-like circulation within the jet entrance region. It is further demonstrated that several EAWM indices are statistically significantly correlated with jet superposition frequency in the west Pacific. The life cycle of EAWM cold surges promotes interaction between tropical convection and internal jet dynamics. Low potential vorticity (PV), high theta e tropical boundary layer air, exhausted by anomalous convection in the west Pacific lower latitudes, is advected poleward towards the equatorward side of the jet in upper tropospheric isentropic layers resulting in anomalous anticyclonic wind shear that accelerates the jet. This, along with geostrophic cold air advection in the left jet entrance region that drives the polar tropopause downward through the jet core, promotes the development of the deep, vertical PV wall characteristic of superposed jets. West Pacific jet superpositions preferentially form within an environment favoring the aforementioned characteristics regardless of EAWM seasonal strength. Post-superposition, it is shown that the west Pacific jet extends eastward and is associated with an upper tropospheric cyclonic (anticyclonic) anomaly in its left (right) exit region. A downstream ridge is present over northwest Canada, and within the strong EAWM environment, a wavier flow over North America is observed relative to the neutral EAWM environment. Preliminary investigation of the two weak EAWM season superpositions reveals a Kona Low type feature post-superposition. This is associated with anomalous convection reminiscent of an atmospheric river southwest of Mexico.

The cocoon emission - an electromagnetic counterpart to gravitational waves from neutron star mergers

NASA Astrophysics Data System (ADS)

Gottlieb, Ore; Nakar, Ehud; Piran, Tsvi

2018-01-01

Short gamma-ray bursts are believed to arise from compact binary mergers (either neutron star-neutron star or black hole-neutron star). If so, their jets must penetrate outflows that are ejected during the merger. As a jet crosses the ejecta, it dissipates its energy, producing a hot cocoon that surrounds it. We present here 3D numerical simulations of jet propagation in mergers' outflows, and we calculate the resulting emission. This emission consists of two components: the cooling emission, the leakage of the thermal energy of the hot cocoon, and the cocoon macronova that arises from the radioactive decay of the cocoon's material. This emission gives a brief (∼1 h) blue, wide angle signal. While the parameters of the outflow and jet are uncertain, for the configurations we have considered, the signal is bright (∼-14 to -15 absolute magnitude) and outshines all other predicted ultraviolet-optical signals. The signal is brighter when the jet breakout time is longer, and its peak brightness does not depend strongly on the highly uncertain opacity. A rapid search for such a signal is a promising strategy to detect an electromagnetic merger counterpart. A detected candidate could be then followed by deep infrared searches for the longer but weaker macronova arising from the rest of the ejecta.

Three-pattern decomposition of global atmospheric circulation: part II—dynamical equations of horizontal, meridional and zonal circulations

NASA Astrophysics Data System (ADS)

Hu, Shujuan; Cheng, Jianbo; Xu, Ming; Chou, Jifan

2018-04-01

The three-pattern decomposition of global atmospheric circulation (TPDGAC) partitions three-dimensional (3D) atmospheric circulation into horizontal, meridional and zonal components to study the 3D structures of global atmospheric circulation. This paper incorporates the three-pattern decomposition model (TPDM) into primitive equations of atmospheric dynamics and establishes a new set of dynamical equations of the horizontal, meridional and zonal circulations in which the operator properties are studied and energy conservation laws are preserved, as in the primitive equations. The physical significance of the newly established equations is demonstrated. Our findings reveal that the new equations are essentially the 3D vorticity equations of atmosphere and that the time evolution rules of the horizontal, meridional and zonal circulations can be described from the perspective of 3D vorticity evolution. The new set of dynamical equations includes decomposed expressions that can be used to explore the source terms of large-scale atmospheric circulation variations. A simplified model is presented to demonstrate the potential applications of the new equations for studying the dynamics of the Rossby, Hadley and Walker circulations. The model shows that the horizontal air temperature anomaly gradient (ATAG) induces changes in meridional and zonal circulations and promotes the baroclinic evolution of the horizontal circulation. The simplified model also indicates that the absolute vorticity of the horizontal circulation is not conserved, and its changes can be described by changes in the vertical vorticities of the meridional and zonal circulations. Moreover, the thermodynamic equation shows that the induced meridional and zonal circulations and advection transport by the horizontal circulation in turn cause a redistribution of the air temperature. The simplified model reveals the fundamental rules between the evolution of the air temperature and the horizontal, meridional and zonal components of global atmospheric circulation.

Climatology of mesopause region nocturnal temperature, zonal wind, and sodium density observed by sodium lidar over Hefei, China (32°N, 117°E)

NASA Astrophysics Data System (ADS)

Li, T.; Ban, C.; Fang, X.; Li, J.; Wu, Z.; Xiong, J.; Feng, W.; Plane, J. M. C.

2017-12-01

The University of Science and Technology of China narrowband sodium temperature/wind lidar, located in Hefei, China (32°N, 117°E), was installed in November 2011 and have made routine nighttime measurements since January 2012. We obtained 154 nights ( 1400 hours) of vertical profiles of temperature, sodium density, and zonal wind, and 83 nights ( 800 hours) of vertical flux of gravity wave (GW) zonal momentum in the mesopause region (80-105 km) during the period of 2012 to 2016. In temperature, it is likely that the diurnal tide dominates below 100 km in spring, while the semidiurnal tide dominates above 100 km throughout the year. A clear semiannual variation in temperature is revealed near 90 km, likely related to the tropical mesospheric semiannual oscillation (MSAO). The variability of sodium density is positively correlated with temperature, suggesting that in addition to dynamics, the chemistry may also play an important role in the formation of sodium atoms. The observed sodium peak density is 1000 cm-3 higher than that simulated by the model. In zonal wind, the diurnal tide dominates in both spring and fall, while semidiurnal tide dominates in winter. The observed semiannual variation in zonal wind near 90 km is out-of-phase with that in temperature, consistent with tropical MSAO. The GW zonal momentum flux is mostly westward in fall and winter, anti-correlated with eastward zonal wind. The annual mean flux averaged over 87-97 km is -0.3 m2/s2 (westward), anti-correlated with eastward zonal wind of 10 m/s. The comparisons of lidar results with those observed by satellite, nearby radar, and simulated by model show generally good agreements.

Observed variability in the upper layers at the Equator, 90°E in the Indian Ocean during 2001-2008, 1: zonal currents

NASA Astrophysics Data System (ADS)

Rao, R. R.; Horii, T.; Masumoto, Y.; Mizuno, K.

2017-08-01

The observed variability of zonal currents (ZC) at the Equator, 90°E shows a strong seasonal cycle in the near-surface 40-350 m water column with periodic east-west reversals most pronounced at semiannual frequency. Superposed on this, a strong intraseasonal variability of 30-90 day periodicity is also prominently seen in the near-surface layer (40-80 m) almost throughout the year with the only exception of February-March. An eastward flowing equatorial undercurrent (EUC) is present in the depth range of 80-160 m during March-April and October-November. The observed intraseasonal variability in the near-surface layer is primarily determined by the equatorial zonal westerly wind bursts (WWBs) through local frictional coupling between the zonal flow in the surface layer and surface zonal winds and shows large interannual variability. The eastward flowing EUC maintained by the ZPG set up by the east-west slope of the thermocline remotely controlled by the zonal wind (ZW) and zonally propagating wave fields also shows significant interannual variability. This observed variability on interannual time scales appears to be controlled by the corresponding variability in the alongshore winds off the Somalia coast during the preceding boreal winter, the ZW field along the equator, and the associated zonally propagating Kelvin and Rossby waves. The salinity induced vertical stratification observed in the near-surface layer through barrier layer thickness (BLT) effects also shows a significant influence on the ZC field on intraseasonal time scale. Interestingly, among all the 8 years (2001-2008), relatively weaker annual cycle is seen in both ZC in the 40-350 m water column and boreal spring sea surface temperature (SST) only during 2001 and 2008 along the equator caused through propagating wave dynamics.

Parameterization of eddy sensible heat transports in a zonally averaged dynamic model of the atmosphere

NASA Technical Reports Server (NTRS)

Genthon, Christophe; Le Treut, Herve; Sadourny, Robert; Jouzel, Jean

1990-01-01

A Charney-Branscome based parameterization has been tested as a way of representing the eddy sensible heat transports missing in a zonally averaged dynamic model (ZADM) of the atmosphere. The ZADM used is a zonally averaged version of a general circulation model (GCM). The parameterized transports in the ZADM are gaged against the corresponding fluxes explicitly simulated in the GCM, using the same zonally averaged boundary conditions in both models. The Charney-Branscome approach neglects stationary eddies and transient barotropic disturbances and relies on a set of simplifying assumptions, including the linear appoximation, to describe growing transient baroclinic eddies. Nevertheless, fairly satisfactory results are obtained when the parameterization is performed interactively with the model. Compared with noninteractive tests, a very efficient restoring feedback effect between the modeled zonal-mean climate and the parameterized meridional eddy transport is identified.

Regulation of electron temperature gradient turbulence by zonal flows driven by trapped electron modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asahi, Y., E-mail: y.asahi@nr.titech.ac.jp; Tsutsui, H.; Tsuji-Iio, S.

2014-05-15

Turbulent transport caused by electron temperature gradient (ETG) modes was investigated by means of gyrokinetic simulations. It was found that the ETG turbulence can be regulated by meso-scale zonal flows driven by trapped electron modes (TEMs), which are excited with much smaller growth rates than those of ETG modes. The zonal flows of which radial wavelengths are in between the ion and the electron banana widths are not shielded by trapped ions nor electrons, and hence they are effectively driven by the TEMs. It was also shown that an E × B shearing rate of the TEM-driven zonal flows is larger thanmore » or comparable to the growth rates of long-wavelength ETG modes and TEMs, which make a main contribution to the turbulent transport before excitation of the zonal flows.« less

A PRELIMINARY JUPITER MODEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hubbard, W. B.; Militzer, B.

In anticipation of new observational results for Jupiter's axial moment of inertia and gravitational zonal harmonic coefficients from the forthcoming Juno orbiter, we present a number of preliminary Jupiter interior models. We combine results from ab initio computer simulations of hydrogen–helium mixtures, including immiscibility calculations, with a new nonperturbative calculation of Jupiter's zonal harmonic coefficients, to derive a self-consistent model for the planet's external gravity and moment of inertia. We assume helium rain modified the interior temperature and composition profiles. Our calculation predicts zonal harmonic values to which measurements can be compared. Although some models fit the observed (pre-Juno) second-more » and fourth-order zonal harmonics to within their error bars, our preferred reference model predicts a fourth-order zonal harmonic whose absolute value lies above the pre-Juno error bars. This model has a dense core of about 12 Earth masses and a hydrogen–helium-rich envelope with approximately three times solar metallicity.« less

Subsurface Zonal and Meridional Flows from SDO/HMI

NASA Astrophysics Data System (ADS)

Komm, Rudolf; Howe, Rachel; Hill, Frank

2016-10-01

We study the solar-cycle variation of the zonal and meridional flows in the near-surface layers of the solar convection zone from the surface to a depth of about 16 Mm. The flows are determined from SDO/HMI Dopplergrams using the HMI ring-diagram pipeline. The zonal and meridional flows vary with the solar cycle. Bands of faster-than-average zonal flows together with more-poleward-than-average meridional flows move from mid-latitudes toward the equator during the solar cycle and are mainly located on the equatorward side of the mean latitude of solar magnetic activity. Similarly, bands of slower-than-average zonal flows together with less-poleward-than-average meridional flows are located on the poleward side of the mean latitude of activity. Here, we will focus on the variation of these flows at high latitudes (poleward of 50 degree) that are now accessible using HMI data. We will present the latest results.

Theory of Fine-scale Zonal Flow Generation From Trapped Electron Mode Turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu Wang and T.S. Hahm

Most existing zonal flow generation theory has been developed with a usual assumption of qrρθ¡ << 1 (qr is the radial wave number of zonal flow, and ρθ¡ is the ion poloidal gyrora- dius). However, recent nonlinear gyrokinetic simulations of trapped electron mode (TEM) turbulence exhibit a relatively short radial scale of the zonal flows with qrρθ¡ ~ 1 [Z. Lin et al., IAEA-CN/TH/P2-8 (2006); D. Ernst et al., Phys. Plasmas 16, 055906 (2009)]. This work reports an extension of zonal flow growth calculation to this short wavelength regime via the wave kinetics approach. A generalized expression for the polarizationmore » shielding for arbitrary radial wavelength [Lu Wang and T.S. Hahm, to appear in Phys. Plasmas (2009)] which extends the Rosenbluth-Hinton formula in the long wavelength limit is applied.« less

Baroclinic stationary waves in aquaplanet models

NASA Astrophysics Data System (ADS)

Lucarini, V.; Zappa, G.

2012-04-01

An aquaplanet model is used to study the nature of the highly persistent low frequency waves that have been observed in models forced by zonally symmetric boundary conditions. Using the Hayashi spectral analysis of the extratropical waves, we find that a quasi-stationary (QS) wave five belongs to a wave packet obeying a well defined dispersion relation with eastward group velocity. The components of the dispersion relation with k>5 baroclinically convert eddy available potential energy into eddy kinetic energy, while those with k<5 are baroclinically neutral. In agreement with the Green's model of baroclinic instability, the wave five is weakly unstable, and the inverse energy cascade, which had been previously proposed as a main forcing for this type of waves, only acts as a positive feedback on its predominantly baroclinic energetics. The QS wave is reinforced by a phase lock to an analogous pattern in the tropical convection, which provides further amplification to the wave. We also find that the Pedlosky bounds on the phase speed of unstable waves provide guidance in explaining the latitudinal structure of the energy conversion, which is shown to be more enhanced where the zonal westerly surface wind is weaker. The wave energy is then trapped in the wave guide created by the upper tropospheric jet stream. In agreement with Green's theory, as the equator to pole SST difference is reduced the stationary marginally stable component shifts toward higher wavenumbers, while the wave five becomes neutral and westward propagating. Some properties of the aquaplanet QS waves are found in interesting agreement with a low frequency wave observed by Salby (1982) in the southern hemisphere DJF, so that this perspective on low frequency variability might be, apart from its value in terms of basic geophysical fluid dynamics, of specific interest for studying the Earth's atmosphere.

Clusters of cyclones encircling Jupiter’s poles

NASA Astrophysics Data System (ADS)

Adriani, A.; Mura, A.; Orton, G.; Hansen, C.; Altieri, F.; Moriconi, M. L.; Rogers, J.; Eichstädt, G.; Momary, T.; Ingersoll, A. P.; Filacchione, G.; Sindoni, G.; Tabataba-Vakili, F.; Dinelli, B. M.; Fabiano, F.; Bolton, S. J.; Connerney, J. E. P.; Atreya, S. K.; Lunine, J. I.; Tosi, F.; Migliorini, A.; Grassi, D.; Piccioni, G.; Noschese, R.; Cicchetti, A.; Plainaki, C.; Olivieri, A.; O’Neill, M. E.; Turrini, D.; Stefani, S.; Sordini, R.; Amoroso, M.

2018-03-01

The familiar axisymmetric zones and belts that characterize Jupiter’s weather system at lower latitudes give way to pervasive cyclonic activity at higher latitudes. Two-dimensional turbulence in combination with the Coriolis β-effect (that is, the large meridionally varying Coriolis force on the giant planets of the Solar System) produces alternating zonal flows. The zonal flows weaken with rising latitude so that a transition between equatorial jets and polar turbulence on Jupiter can occur. Simulations with shallow-water models of giant planets support this transition by producing both alternating flows near the equator and circumpolar cyclones near the poles. Jovian polar regions are not visible from Earth owing to Jupiter’s low axial tilt, and were poorly characterized by previous missions because the trajectories of these missions did not venture far from Jupiter’s equatorial plane. Here we report that visible and infrared images obtained from above each pole by the Juno spacecraft during its first five orbits reveal persistent polygonal patterns of large cyclones. In the north, eight circumpolar cyclones are observed about a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. Cyclonic circulation is established via time-lapse imagery obtained over intervals ranging from 20 minutes to 4 hours. Although migration of cyclones towards the pole might be expected as a consequence of the Coriolis β-effect, by which cyclonic vortices naturally drift towards the rotational pole, the configuration of the cyclones is without precedent on other planets (including Saturn’s polar hexagonal features). The manner in which the cyclones persist without merging and the process by which they evolve to their current configuration are unknown.

Comparison of large-scale dynamical variability in the extratropical stratosphere among the JRA-55 family data sets: impacts of assimilation of observational data in JRA-55 reanalysis data

NASA Astrophysics Data System (ADS)

Taguchi, Masakazu

2017-09-01

This study compares large-scale dynamical variability in the extratropical stratosphere, such as major stratospheric sudden warmings (MSSWs), among the Japanese 55-year Reanalysis (JRA-55) family data sets. The JRA-55 family consists of three products: a standard product (STDD) of the JRA-55 reanalysis data and two sub-products of JRA-55C (CONV) and JRA-55AMIP (AMIP). CONV assimilates only conventional surface and upper-air observations without assimilation of satellite observations, whereas AMIP runs the same numerical weather prediction model without assimilation of observational data. A comparison of the occurrence of MSSWs in Northern Hemisphere (NH) winter shows that, compared to STDD, CONV delays several MSSWs by 1 to 4 days and also misses a few MSSWs. CONV also misses the Southern Hemisphere (SH) MSSW in September 2002. AMIP shows significantly fewer MSSWs in Northern Hemisphere winter and especially lacks MSSWs of the high aspect ratio of the polar vortex in which the vortex is highly stretched or split. A further examination of daily geopotential height differences between STDD and CONV reveals occasional peaks in both hemispheres that are separated from MSSWs. The delayed and missed MSSW cases have smaller height differences in magnitude than such peaks. The height differences for those MSSWs include large contributions from the zonal component, which reflects underestimations in the weakening of the zonal mean polar night jet in CONV. We also explore strong planetary wave forcings and associated polar vortex weakenings for STDD and AMIP. We find a lower frequency of strong wave forcings and weaker vortex responses to such wave forcings in AMIP, consistent with the lower MSSW frequency.

On the wave number 2 eastward propagating quasi 2 day wave at middle and high latitudes

NASA Astrophysics Data System (ADS)

Gu, Sheng-Yang; Liu, Han-Li; Pedatella, N. M.; Dou, Xiankang; Liu, Yu

2017-04-01

The temperature and wind data sets from the ensemble data assimilation version of the Whole Atmosphere Community Climate Model + Data Assimilation Research Testbed (WACCM + DART) developed at the National Center for Atmospheric Research (NCAR) are utilized to study the seasonal variability of the eastward quasi 2 day wave (QTDW) with zonal wave number 2 (E2) during 2007. The aliasing ratio of E2 from wave number 3 (W3) in the synoptic WACCM data set is a constant value of 4 × 10-6% due to its uniform sampling pattern, whereas the aliasing is latitudinally dependent if the WACCM fields are sampled asynoptically based on the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) sampling. The aliasing ratio based on SABER sampling is 75% at 40°S during late January, where and when W3 peaks. The analysis of the synoptic WACCM data set shows that the E2 is in fact a winter phenomenon, which peaks in the stratosphere and lower mesosphere at high latitudes. In the austral winter period, the amplitudes of E2 can reach 10 K, 20 m/s, and 30 m/s for temperature, zonal, and meridional winds, respectively. In the boreal winter period, the wave perturbations are only one third as strong as those in austral winter. Diagnostic analysis also shows that the mean flow instabilities in the winter upper mesosphere polar region provide sources for the amplification of E2. This is different from the westward QTDWs, whose amplifications are related to the summer easterly jet. In addition, the E2 also peaks at lower altitude than the westward modes.

The solsticial pause on Mars: 2 modelling and investigation of causes

NASA Astrophysics Data System (ADS)

Mulholland, David P.; Lewis, Stephen R.; Read, Peter L.; Madeleine, Jean-Baptiste; Forget, Francois

2016-01-01

The martian solsticial pause, presented in a companion paper (Lewis et al., 2016), was investigated further through a series of model runs using the UK version of the LMD/UK Mars Global Climate Model. It was found that the pause could not be adequately reproduced if radiatively active water ice clouds were omitted from the model. When clouds were used, along with a realistic time-dependent dust opacity distribution, a substantial minimum in near-surface transient eddy activity formed around solstice in both hemispheres. The net effect of the clouds in the model is, by altering the thermal structure of the atmosphere, to decrease the vertical shear of the westerly jet near the surface around solstice, and thus reduce baroclinic growth rates. A similar effect was seen under conditions of large dust loading, implying that northern midlatitude eddy activity will tend to become suppressed after a period of intense flushing storm formation around the northern cap edge. Suppression of baroclinic eddy generation by the barotropic component of the flow and via diabatic eddy dissipation were also investigated as possible mechanisms leading to the formation of the solsticial pause but were found not to make major contributions. Zonal variations in topography were found to be important, as their presence results in weakened transient eddies around winter solstice in both hemispheres, through modification of the near-surface flow. The zonal topographic asymmetry appears to be the primary reason for the weakness of eddy activity in the southern hemisphere relative to the northern hemisphere, and the ultimate cause of the solsticial pause in both hemispheres. The meridional topographic gradient was found to exert a much weaker influence on near-surface transient eddies.

Observed and modeled mesoscale variability near the Gulf Stream and Kuroshio Extension

NASA Astrophysics Data System (ADS)

Schmitz, William J.; Holland, William R.

1986-08-01

Our earliest intercomparisons between western North Atlantic data and eddy-resolving two-layer quasi-geostrophic symmetric-double-gyre steady wind-forced numerical model results focused on the amplitudes and largest horizontal scales in patterns of eddy kinetic energy, primarily abyssal. Here, intercomparisons are extended to recent eight-layer model runs and new data which allow expansion of the investigation to the Kuroshio Extension and throughout much of the water column. Two numerical experiments are shown to have realistic zonal, vertical, and temporal eddy scales in the vicinity of the Kuroshio Extension in one case and the Gulf Stream in the other. Model zonal mean speeds are larger than observed, but vertical shears are in general agreement with the data. A longitudinal displacement between the maximum intensity in surface and abyssal eddy fields as observed for the North Atlantic is not found in the model results. The numerical simulations examined are highly idealized, notably with respect to basin shape, topography, wind-forcing, and of course dissipation. Therefore the zero-order agreement between modeled and observed basic characteristics of mid-latitude jets and their associated eddy fields suggests that such properties are predominantly determined by the physical mechanisms which dominate the models, where the fluctuations are the result of instability processes. The comparatively high vertical resolution of the model is needed to compare with new higher-resolution data as well as for dynamical reasons, although the precise number of layers required either kinematically or dynamically (or numerically) has not been determined; we estimate four to six when no attempt is made to account for bottom- or near-surface-intensified phenomena.

Particle content, radio-galaxy morphology, and jet power: all radio-loud AGN are not equal

NASA Astrophysics Data System (ADS)

Croston, J. H.; Ineson, J.; Hardcastle, M. J.

2018-05-01

Ongoing and future radio surveys aim to trace the evolution of black hole growth and feedback from active galactic nuclei (AGNs) throughout cosmic time; however, there remain major uncertainties in translating radio luminosity functions into a reliable assessment of the energy input as a function of galaxy and/or dark matter halo mass. A crucial and long-standing problem is the composition of the radio-lobe plasma that traces AGN jet activity. In this paper, we carry out a systematic comparison of the plasma conditions in Fanaroff & Riley class I and II radio galaxies to demonstrate conclusively that their internal composition is systematically different. This difference is best explained by the presence of an energetically dominant proton population in the FRI, but not the FRII radio galaxies. We show that, as expected from this systematic difference in particle content, radio morphology also affects the jet-power/radio-luminosity relationship, with FRII radio galaxies having a significantly lower ratio of jet power to radio luminosity than the FRI cluster radio sources used to derive jet-power scaling relations via X-ray cavity measurements. Finally, we also demonstrate conclusively that lobe composition is unconnected to accretion mode (optical excitation class): the internal conditions of low- and high-excitation FRII radio lobes are indistinguishable. We conclude that inferences of population-wide AGN impact require careful assessment of the contribution of different jet subclasses, particularly given the increased diversity of jet evolutionary states expected to be present in deep, low-frequency radio surveys such as the LOFAR Two-Metre Sky Survey.

The Thermal Structure, Dust Loading, and Meridional Transport in the Martian Atmosphere during Late Southern Summer.

NASA Astrophysics Data System (ADS)

Santee, Michelle

The thermal structure, dust loading, and meridional transport in the Martian atmosphere are investigated using thermal emission spectra recorded by the Mariner 9 infrared interferometer spectrometer (IRIS). The analysis is restricted to a subset of the IRIS data consisting of approximately 2400 spectra spanning L_{S} = 343^circ-348^ circ, corresponding to late southern summer on Mars. Simultaneous retrieval of the vertical distribution of both atmospheric temperature and dust optical depth is accomplished through an iterative procedure which is performed on each spectrum. Although atmospheric temperatures decrease from equator to pole at lower altitudes, both dayside and nightside temperatures above about 0.1 mbar (~40 km) are warmer over the winter (north) polar region than over the equator or the summer (south) polar region. Zonal-mean zonal winds are derived from the atmospheric temperatures assuming gradient wind balance and zero surface zonal wind. Both hemispheres have intense mid-latitude westerly jets (with velocities of 80-90 m/s near 50 km); in the southern tropics the winds are strongly easterly (with velocities of 100 m/s near 50 km). A comprehensive radiative transfer model (Crisp, 1990) is used to compute solar heating and thermal cooling rates from the retrieved IRIS temperature and dust distributions. There are large net heating rates (up to 8 K/day) in the equatorial region and large net cooling rates (up to 20 K/day) in the polar regions. These net heating rates are used in a diagnostic stream function model which solves for the meridional and vertical components of the diabatic circulation simultaneously. The results show a vigorous two-cell circulation, with rising motion over the equatorial region ( ~1.5 cm/s), poleward flow in both hemispheres (~2 m/s), sinking motion over both polar regions (1-2 cm/s), and return flow in the lowest atmospheric levels. The meridional transport time scale is ~13 days. Water vapor desorbed from the low-latitude regolith during late northern winter/early northern spring may be transported upward by the ascending branch of this circulation, where it may be advected back to the polar regions by the high-altitude meridional winds. This process could provide a high-altitude source of water vapor for the formation and maintenance of the north polar hood.

Multiproxy Reduced-Dimension Reconstruction of Holocene Tropical Pacific SST Fields and Indian Monsoon Variability

NASA Astrophysics Data System (ADS)

Gill, E.; Rajagopalan, B.; Molnar, P. H.; Marchitto, T. M., Jr.; Kushnir, Y.

2016-12-01

We develop a multiproxy reduced-dimension methodology that blends magnesium calcium (Mg/Ca) and alkenone (UK'37) paleo sea surface temperature (SST) records from the eastern and western equatorial Pacific to recreate snapshots of full field SSTs and zonal wind anomalies from 10 to 2 ka BP in 2000-year increments. In the reconstruction, the zonal SST difference (average west Pacific SST minus average east Pacific SST) is largest at 10 ka (0.26°C), with coldest SST anomalies of -0.9°C in the eastern equatorial Pacific and concurrent easterly maximum zonal wind anomalies of 7 m s-1 throughout the central Pacific. From 10 to 2 ka, the entire equatorial Pacific warms, but at a faster rate in the east than in the west. These patterns are broadly consistent with previous inferences of reduced El Niño-Southern Oscillation variability associated with a cooler and/or "La Niña-like" state during the early to middle Holocene. At present there is a strong negative correlation between tropical pacific SSTs and Indian summer monsoon strength. Assuming ENSO-monsoon teleconnections were the same during early Holocene, we would expect a cooler tropical Pacific to enhance the summer Indian monsoon. To test this idea, we used the same tropical Pacific SST proxy records and a similar reduced-dimension technique to reconstruct fields of Arabian Sea wind-stress curl and Indian summer monsoon precipitation. Reconstructions for 10 ka reveal wind-stress curl anomalies of 30% greater than present day off the coastlines of Oman and Yemen, which suggest greater coastal upwelling and an enhanced monsoon jet during this time. Spatial rainfall reconstructions reveal the greatest difference in precipitation at 10 ka over the core monsoon region ( 20-60% greater than present day). Specifically, reconstructions from 10 ka reveal 40-60% greater rainfall over North West India, a region home to abundant paleo-lake records spanning the Holocene but is at present remarkably dry ( 200-450 mm of annual rainfall). These findings advance the hypothesis that teleconnections from the tropical Pacific contributed to, if not accounted for, greater early to middle Holocene wetness over India as recorded by various (e.g., cave, lacustrine, river discharge) paleoclimate proxies throughout the monsoon region.

The observed life cycle of a baroclinic instability

NASA Technical Reports Server (NTRS)

Randel, W. J.; Stanford, J. L.

1985-01-01

Medium-scale waves (zonal wavenumbers 4-7) frequently dominate Southern Hemisphere summer circulation patterns. Randel and Stanford have studied the dynamics of these features, demonstrating that the medium-scale waves result from baroclinic excitation and exhibit well-defined life cycles. This study details the evolution of the medium-scale waves during a particular life cycle. The specific case chosen exhibits a high degree of zonal symmetry, prompting study based upon zonally averaged diagnostics. An analysis of the medium-scale wave energetics reveals a well-defined life cycle of baroclinic growth, maturity, and barotropic decay. Eliassen-Palm flux diagrams detail the daily wave structure and its interaction with the zonally-averaged flow.

Cattaraugus Creek Harbor, New York General Design Memorandum. Phase II. (Detailed Design). Volume II. Appendix E. Littoral Processes and Sedimentation in the Cattaraugus Embayment, New York. Appendix F. Sediment Transport in Cattaraugus Creek.

DTIC Science & Technology

1976-03-01

beaches than any other part of the southeastern shoreline of Lake Erie . It is the only major sand accumulation zone with the exception of Presque Isle , in...52 20. Photographs of zonal site #10. 54 21. Photograph and map of zonal site #11, Presque Isle , Pa. 57 F22. Photographs and beach profiles at zonal...site #11. 59 23. Photograph of zonal site #12, the recurved spit area on Presque Isle , Pa. 62 24. Block diagram of recurved spit area of Presque Isle

Secular variations in zonal harmonics of Earth's geopotential and their implications for mantle viscosity and Antarctic melting history due to the last deglaciation

NASA Astrophysics Data System (ADS)

Nakada, Masao; Okuno, Jun'ichi

2017-06-01

Secular variations in zonal harmonics of Earth's geopotential based on the satellite laser ranging observations, {\\dot{J}_n}, contain important information about the Earth's deformation due to the glacial isostatic adjustment (GIA) and recent melting of glaciers and the Greenland and Antarctic ice sheets. Here, we examine the GIA-induced {\\dot{J}_n}, \\dot{J}_n^{GIA} (2 ≤ n ≤ 6), derived from the available geopotential zonal secular rate and recent melting taken from the IPCC 2013 Report (AR5) to explore the possibility of additional information on the depth-dependent lower-mantle viscosity and GIA ice model inferred from the analyses of the \\dot{J}_2^{GIA} and relative sea level changes. The sensitivities of the \\dot{J}_n^{GIA} to lower-mantle viscosity and GIA ice model with a global averaged eustatic sea level (ESL) of ∼130 m indicate that the secular rates for n = 3 and 4 are mainly caused by the viscous response of the lower mantle to the melting of the Antarctic ice sheet regardless of GIA ice models adopted in this study. Also, the analyses of the \\dot{J}_n^{GIA} based on the available geopotential zonal secular rates indicate that permissible lower-mantle viscosity structure satisfying even zonal secular rates of n = 2, 4 and 6 is obtained for the GIA ice model with an Antarctic ESL component of ∼20 or ∼30 m, but there is no viscosity solution satisfying \\dot{J}_3^{GIA} and \\dot{J}_5^{GIA} values. Moreover, the inference model for the lower-mantle viscosity and GIA ice model from each odd zonal secular rate is distinctly different from that satisfying GIA-induced even zonal secular rate. The discrepancy between the inference models for the even and odd zonal secular rates may partly be attributed to uncertainties of the geopotential zonal secular rates for n > 2 and particularly those for odd zonal secular rates due to weakness in the orbital geometry. If this problem is overcome at least for the secular rates of n < 5, then the analyses of the \\dot{J}_n^{GIA} would make it possible to put more convincing constraints on the lower-mantle viscosity structure and GIA ice model, particularly for the controversial Antarctic melting history in GIA community.

Hadley cell dynamics of a cold and virtually dry Snowball Earth atmosphere

NASA Astrophysics Data System (ADS)

Voigt, Aiko; Held, Isaac; Marotzke, Jochem

2010-05-01

We use the full-physics atmospheric general circulation model ECHAM5 to investigate a cold and virtually dry Snowball Earth atmosphere that results from specifying sea ice as the surface boundary condition everywhere, corresponding to a frozen aquaplanet, while keeping total solar irradiance at its present-day value of 1365 Wm-2. The aim of this study is the investigation of the zonal-mean circulation of a Snowball Earth atmosphere, which, due to missing moisture, might constitute an ideal though yet unexplored testbed for theories of atmospheric dynamics. To ease comparison with theories, incoming solar insolation follows permanent equinox conditions with disabled diurnal cycle. The meridional circulation consists of a thermally direct cell extending from the equator to 45 N/S with ascent in the equatorial region, and a weak thermally indirect cell with descent between 45 and 65 N/S and ascent in the polar region. The former cell corresponds to the present-day Earth's Hadley cell, while the latter can be viewed as an eddy-driven Ferrell cell; the present-day Earth's direct polar cell is missing. The Hadley cell itself is subdivided into a vigorous cell confined to the troposphere and a weak deep cell reaching well into the stratosphere. The dynamics of the vigorous Snowball Earth Hadley cell differ substantially from the dynamics of the present-day Hadley cell. The zonal momentum balance shows that in the poleward branch of the vigorous Hadley cell, mean flow meridional advection of absolute vorticity is not only balanced by eddy momentum flux convergence but also by vertical diffusion. Inside the poleward branch, eddies are more important in the upper part and vertical diffusion is more important in the lower part. Vertical diffusion also contributes to the meridional momentum balance as it decelerates the vigorous Hadley cell by downgradient momentum mixing between its poleward and equatorward branch. Zonal winds, therefore, are not in thermal wind balance in the vigorous Hadley cell. Suppressing vertical momentum diffusion above 870 hPa results in a doubling of the vigorous Hadley cell strength. Simulations where we only suppress either vertical diffusion of zonal or meridional momentum show that this doubling can be understood from the decelerating effect of vertical diffusion in the meridional momentum balance. Comparing our simulations with theories, we conclude that neither the axisymmetric Hadley cell model of Held & Hou (1980) nor the eddy-permitting model of T. Schneider et al. (2005, 2006, 2008) are applicable to a Snowball Earth atmosphere since both assume an inviscid upper Hadley cell branch.

Activities of the Jet Propulsion Laboratory, 1 January - 31 December 1983

NASA Technical Reports Server (NTRS)

1984-01-01

There are many facets to the Jet Propulsion Laboratory, for JPL is an organization of multiple responsibilities and broad scope, of diverse talents and great enterprise. The Laboratory's philosophy, mission, and goals have been shaped by its ties to the California Institute of Technology (JPL's parent organization) and the National Aeronautics and Space Administration (JPL's principal sponsor). JPL's activities for NASA in planetary, Earth, and space sciences currently account for almost 75 percent of the Laboratory's overall effort. JPL Research activities in the following areas are discussed: (1) deep space exploration; (2) telecommunications systems; (3) Earth observations; (4) advanced technology; (5) defense programs; and (6) energy and technology applications.

Publications of the Jet Propulsion Laboratory, 1980

NASA Technical Reports Server (NTRS)

1981-01-01

This bibliography cites by primary author the externally distributed technical reporting, released during calendar year 1980, that resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory. Three classes of publications are included: (1) JPL Publications (77-, 78-, 79-series, etc.), in which the information is complete for a specific accomplishment and can e tailored to wide or limited audiences and be presented in an established standard format or special format to meet unique requirements; (2) articles published in the open literature; and (3) articles from the bimonthly Deep Space Network (DSN) Progress Repot (42-series) and its successor, the Telecommunications and Data Acquisition (TDA) Progress Report (also 42-series).

Diagnostic budgets of analyzed and modelled tropical plumes

NASA Technical Reports Server (NTRS)

Mcguirk, James P.; Vest, Gerry W.

1993-01-01

Blackwell et al. successfully simulated tropical plumes in a global barotropic model valid at 200 mb. The plume evolved in response to strong equatorial convergence which simulated a surge in the Walker Circulation. The defining characteristics of simulated plumes are: a subtropical jet with southerlies emanating from the deep tropics; a tropical/mid-latitude trough to the west; a convergence/divergence dipole straddling the trough; and strong cross contour flow at the tropical base of the jet. Diagnostic budgets of vorticity, divergence, and kinetic energy are calculated to explain the evolution of the modelled plumes. Budgets describe the unforced (basic) state, forced plumes, forced cases with no plumes, and ECMWF analyzed plumes.

YANG-MILLS Theory in, Beyond, and Behind Observed Reality

NASA Astrophysics Data System (ADS)

Wilczek, Frank

The primary interactions of Yang-Mills theory [1] are visibly embodied in hard processes, most directly in jets. The character of jets also reflects the deep structure of effective charge, which is dominated by the influence of intrinsically non-Abelian gauge dynamics. These proven insights into fundamental physics ramify in many directions, and are far from being exhausted. I will discuss three rewarding explorations from my own experience, whose point of departure is the hard Yang-Mills interaction, and whose end is not yet in sight. Given an insight so profound and fruitful as Yang and Mills brought us, it is in order to try to consider its broadest implications, which I attempt at the end.

Publications of the Jet Propulsion Laboratory, 1980

NASA Astrophysics Data System (ADS)

1981-07-01

This bibliography cites by primary author the externally distributed technical reporting, released during calendar year 1980, that resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory. Three classes of publications are included: (1) JPL Publications (77-, 78-, 79-series, etc.), in which the information is complete for a specific accomplishment and can e tailored to wide or limited audiences and be presented in an established standard format or special format to meet unique requirements; (2) articles published in the open literature; and (3) articles from the bimonthly Deep Space Network (DSN) Progress Report (42-series) and its successor, the Telecommunications and Data Acquisition (TDA) Progress Report (also 42-series).

Tracking the origins of plastic debris across the Coral Sea: A case study from the Ouvéa Island, New Caledonia.

PubMed

Maes, Christophe; Blanke, Bruno

2015-08-15

Contamination of the marine environment by human-made plastic litter is a growing and global problem. Our study attempts to explain the presence of two plastic bottles beached on the Ouvéa Island, in the southwest Pacific Ocean, with trademarks from the Solomon Islands and Papua New Guinea (PNG). We simulate the oceanic drift tracks and associated transit times with a Lagrangian interpretation of the surface currents of a high-resolution ocean model. Our results show that it takes less than 2-3months for drifting objects to connect these archipelagos (New Caledonia, Solomon Islands and PNG) and highlight the role of the meridional component of the circulation rather than the dominant zonal jets. This study shows that the origin or traceability of trash represent valuable information that can be used to test and, ultimately, improve our understanding of ocean circulation. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

The role of zonally asymmetric heating in the vertical and temporal structure of the global scale flow fields during FGGE SOP-1. [First Global Atmospheric Research Program Global Experiment (FGGE); Special Observing Period (SOP)

NASA Technical Reports Server (NTRS)

Paegle, J.; Kalnay-Rivas, E.; Baker, W. E.

1981-01-01

By examining the vertical structure of the low order spherical harmonics of the divergence and vorticity fields, the relative contribution of tropical and monsoonal circulations upon the global wind fields was estimated. This indicates that the overall flow over North America and the Pacific between January and February is quite distinct both in the lower and upper troposphere. In these longitudes there is a stronger tropical overturning and subtropical jet stream in January than February. The divergent flow reversed between 850 and 200 mb. Poleward rotational flow at upper levels is associated with an equatorward rotational flow at low levels. This suggests that the monsoon and other tropical circulations project more amplitude upon low order (global scale) representations of the flow than do the typical midlatitude circulations and that their structures show conspicuous changes on a time scale of a week or less.

Impacts of Early Summer Eurasian Snow Cover Change on Atmospheric Circulation in Northern Mid-Latitudes

NASA Astrophysics Data System (ADS)

Nozawa, T.

2016-12-01

Recently, Japan Aerospace Exploration Agency (JAXA) has developed a new long-term snow cover extent (SCE) product using Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) data spanning from 1980's to date. This new product (JAXA/SCE) has higher spatial resolution and smaller commission error compared with traditional SCE dataset of National Oceanic and Atmospheric Administration (NOAA/SCE). Continuity of the algorithm is another strong point in JAXA/SCE. According to the new JAXA/SCE dataset, the Eurasian SCE has been significantly retreating since 1980's, especially in late spring and early summer. Here, we investigate impacts of early summer Eurasian snow cover change on atmospheric circulation in Northern mid-latitudes, especially over the East Asia, using the new JAXA/SCE dataset and a few reanalysis data. We will present analyzed results on relationships between early summer SCE anomaly over the Eurasia and changes in atmospheric circulations such as upper level zonal jets (changes in strength, positions, etc.) over the East Asia.

Thermal structure and heat balance of the outer planets

NASA Technical Reports Server (NTRS)

Conrath, B. J.; Hanel, R. A.; Samuelson, R. E.

1989-01-01

Current knowledge of the thermal structure and energy balance of the outer planets is summarized. The Voyager spacecraft experiments have provided extensive new information on the atmospheric temperatures and energetics of Jupiter, Saturn and Uranus. All three planets show remarkably small global-scale horizontal thermal contrast, indicating efficient redistribution of heat within the atmospheres or interiors. Horizontal temperature gradients on the scale of the zonal jets indicate that the winds decay with height in the upper troposphere. This suggests that the winds are driven at deeper levels and are subjected to frictional damping of unknown origin at higher levels. Both Jupiter and Saturn have internal power sources equal to about 70 percent of the absorbed solar power. This result is consistent with the view that significant helium differentiation has occurred on Saturn. Uranus has an internal power no greater than 13 percent of the absorbed solar power, while earth-based observations suggest Neptune has an internal power in excess of 100 percent of the absorbed solar power.

Influence of the North American monsoon on Southern California tropospheric ozone levels during summer in 2013 and 2014

NASA Astrophysics Data System (ADS)

Granados-Muñoz, Maria Jose; Johnson, Matthew S.; Leblanc, Thierry

2017-06-01

The impact of the North American (NA) monsoon on tropospheric ozone variability in Southern California is investigated using lidar measurements at Jet Propulsion Laboratory-Table Mountain Facility, California, and the chemical-transport model GEOS-Chem. Routine lidar observations obtained in July-August 2013-2014 reveal a consistent ozone enhancement of 23 ppbv in the free troposphere (6-9 km), when ozone-rich air is transported along the western edge of the upper level anticyclone associated with the NA monsoon from regions where maximum lightning-induced NOx production occurs. When the high-pressure system shifts to the southeast, a zonal westerly flow of the air parcels reaching the Table Mountain Facility (TMF) occurs, prohibiting the lightning-induced ozone enhanced air to reach TMF. This modulation of tropospheric ozone by the position of the NA monsoon anticyclone could have implications on long-term ozone trends associated with our changing climate, due to the expected widening of the tropical belt affecting the strength and position of the anticyclone.

Structure of the middle atmosphere of Venus and future observation with PFS on Venus Express.

NASA Astrophysics Data System (ADS)

Zasova, L. V.; Formisano, V.; Moroz, V. I.; Ignatiev, N. I.; Khatountsev, I. A.

Investigation of the middle atmosphere of Venus (55 -- 100 km) will allow to advance our knowledge about the most puzzling phenomena of the Venus dynamics -- its superrotation. More than 70% of all absorbed by Venus Solar energy is deposited there, results in the thermal tides generation and giving energy to support the superrotation. The importance of the tides in the middle atmosphere is manifested by the tidal character of the local time variation of the structure of the thermal field, zonal wind field (especially, behavior of the wind speed in the mid latitude jet), upper clouds, with amplitudes depending on the altitude and latitude. Investigation of the middle atmosphere is a scientific goal of the long wavelength channel of PFS on Venus Express, as well as of its short wavelength channel (the latter on the day side). The 3D temperature, aerosol, thermal wind and SO2 abundance fields, spatial distribution of abundance of H2O (possibly vertical profile), CO, HCl, HF will be obtained.

Pinatubo eruption winter climate effects: Model versus observations

NASA Technical Reports Server (NTRS)

Graf, HANS-F.; Kirchner, Ingo; Schult, Ingrid; Robock, Alan

1992-01-01

Large volcanic eruptions, in addition to the well-known effect of producing global cooling for a year or two, have been observed to produce shorter-term responses in the climate system involving non-linear dynamical processes. In this paper, we use the ECHAM2 general circulation model forced with stratospheric aerosols to test some of these ideas. Run in a perpetual-January mode, with tropical stratospheric heating from the volcanic aerosols typical of the 1982 El Chichon eruption or the 1991 Pinatubo eruption, we find a dynamical response with an increased polar night jet in the Northern Hemisphere (NH) and stronger zonal winds which extended down into the troposphere. The Azores High shifts northward with increased tropospheric westerlies at 60N and increased easterlies at 30N. Surface temperatures are higher both in northern Eurasia and North America, in agreement with observations for the NH winters or 1982-83 and 1991-92 as well as the winters following the other 10 largest volcanic eruptions since 1883.

Intensification of upwelling along Oman coast in a warming scenario

NASA Astrophysics Data System (ADS)

Praveen, V.; Ajayamohan, R. S.; Valsala, V.; Sandeep, S.

2016-07-01

The oceanic impact of poleward shift in monsoon low-level jet (MLLJ) is examined using a Regional Ocean Modeling System (ROMS). Two sets of downscaling experiments were conducted using ROMS with boundary and initial conditions from six CMIP5 models. While outputs from the historical run (1981-2000) acts as forcing for the first, the second uses RCP8.5 (2080-2099). By comparing the outputs, it is found that Oman coast will experience an increase in upwelling in tune with MLLJ shift. Consistent with the changes in upwelling and zonal Ekman transport, temperature, salinity, and productivity show significant changes near the Oman coast. The changes in MLLJ causes the coastal wind to angle against the Oman coast in such a fashion that the net upwelling increases in the next century and so does the marine productivity. This study contrasts the general view of weakening of upwelling along the Arabian coasts due to the weakening of monsoon winds.

Upwelling changes along the Arabian coast in a warming scenario

NASA Astrophysics Data System (ADS)

Praveen, V.; Ravindran, A. M.; Valsala, V.; Sandeep, S.

2016-12-01

The oceanic impact of poleward shift in Monsoon Low-Level Jet (MLLJ) is examined using a regional ocean model (ROMS). Two sets of downscaling experiments were conducted using ROMS with boundary and initial conditions from six CMIP5 models. While outputs from the historical run (1981-2000) acts as forcing for the first, the second uses RCP8.5 (2080-2099). By comparing the outputs, it is found that Oman coast will experience an increase in upwelling in tune with MLLJ shift. Consistent with the changes in upwelling and zonal Ekman transport, temperature, salinity and productivity show significant changes near the Oman coast. The changes in MLLJ causes the coastal wind to angle against the Oman coast in such a fashion that the net upwelling increases in the next century and so does the marine productivity. This study contrasts the general view of weakening of upwelling along the Arabian coasts due to the weakening of monsoon winds. Above findings has major implications on the livelihood and economy of the region

The Telecommunications and Data Acquisition Report

NASA Technical Reports Server (NTRS)

Yuen, Joseph H. (Editor)

1994-01-01

This quarterly publication provides archival reports on developments in programs in space communications, radio navigation, radio science, and ground-based radio and radar astronomy. It reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standardization activities at the Jet Propulsion Laboratory for space data and information systems.

Sensors Increase Productivity in Harsh Environments

NASA Technical Reports Server (NTRS)

2008-01-01

California's San Juan Capistrano-based Endevco Corporation licensed three patents covering high-temperature, harsh-environment silicon carbide (Si-C) pressure sensors from Glenn Research Center. The company is exploring their use in government markets, as well as in commercial markets, including commercial jet testing, deep well drilling applications where pressure and temperature increase with drilling depth, and in automobile combustion chambers.

Automated Consultation for the Diagnosis of Interplanetary Telecommunications

NASA Technical Reports Server (NTRS)

Quan, A. G.; Schwuttke, U. M.; Herstein, J. S.; Spagnuolo, J. S.; Burleigh, S.

1995-01-01

SHARP (Spacecraft Health Automated Reasoning Program) is a knowledge-based system for the diagnosis of problems in NASA's Deep Space Network (DSN) telecommunications system. This system provides the means of communication between a spacecraft and operations personnel at Jet Propulsion Laboratory. SHARP analyzes problems that occur in both the on-board spacecraft telecom subsystem, and the DSN.

Injection therapy with triamcinolone hexacetonide in the treatment of burn scars in infancy: results of 44 cases.

PubMed

Grisolia, G A; Danti, D A; Santoro, S; Panozzo, G; Bonini, G; Pampaloni, A

1983-11-01

In many cases deep second degree and third degree burns cause severe scarring. The authors have reported here their experience of the treatment of hypertrophic scarring from burns carried out on 44 children with intralesional injections of a long-acting cortico-steroid (Triamcinolone hexacetonide) using the jet spray technique.

Global Ocean Vertical Velocity From a Dynamically Consistent Ocean State Estimate

NASA Astrophysics Data System (ADS)

Liang, Xinfeng; Spall, Michael; Wunsch, Carl

2017-10-01

Estimates of the global ocean vertical velocities (Eulerian, eddy-induced, and residual) from a dynamically consistent and data-constrained ocean state estimate are presented and analyzed. Conventional patterns of vertical velocity, Ekman pumping, appear in the upper ocean, with topographic dominance at depth. Intense and vertically coherent upwelling and downwelling occur in the Southern Ocean, which are likely due to the interaction of the Antarctic Circumpolar Current and large-scale topographic features and are generally canceled out in the conventional zonally averaged results. These "elevators" at high latitudes connect the upper to the deep and abyssal oceans and working together with isopycnal mixing are likely a mechanism, in addition to the formation of deep and abyssal waters, for fast responses of the deep and abyssal oceans to the changing climate. Also, Eulerian and parameterized eddy-induced components are of opposite signs in numerous regions around the global ocean, particularly in the ocean interior away from surface and bottom. Nevertheless, residual vertical velocity is primarily determined by the Eulerian component, and related to winds and large-scale topographic features. The current estimates of vertical velocities can serve as a useful reference for investigating the vertical exchange of ocean properties and tracers, and its complex spatial structure ultimately permits regional tests of basic oceanographic concepts such as Sverdrup balance and coastal upwelling/downwelling.

Effects of the quasi-biennial oscillation on interannual variability of spring precipitation in the western North Pacific

NASA Astrophysics Data System (ADS)

Seo, J.; Choi, W.; Youn, D.; Park, D. R.; Kim, J.

2013-12-01

The effects of the equatorial quasi-biennial oscillation (QBO) on the springtime rainfall variability in the western North Pacific (WNP) region are examined using the monthly data of GPCP precipitation, NOAA OLR, and ERA-interim reanalysis for the period of 1979-2011. The QBO phases during the spring are based on the Singapore zonal wind at 70 hPa and strong ENSO years are excluded from the analyses to investigate the sole influence of the QBO. The composite analyses of the precipitation, OLR, and related meteorological fields show that the WNP subtropical high (WNPSH) moves equatorward during the westerly QBO (WQBO) compared to the easterly QBO (EQBO) and the convergence region of moisture flux along the northwestern boundary of the WNPSH is displaced southward. In addition, the subtropical jet associated with the midlatitude frontal zone also shifts slightly southward during the WQBO compared to the EQBO. These QBO-related changes in large-scale meteorological fields induce the southward displacement of the midlatitude spring rainband extending from southeastern China to the east of the Japanese Islands and thus significant rainfall decrease in the Northeast Asia during the WQBO compared to the EQBO. The possible role of the QBO in modulating the WNPSH and subtropical jet is also discussed with regard to the strength of the Hadley circulation and the activity of subtropical planetary waves. The results of this study may improve the seasonal predictability of the spring rainfall in the Northeast Asia and the WNP region.

Observed formation of easterly waves over northeast Africa

NASA Astrophysics Data System (ADS)

Jury, Mark R.

2018-06-01

This study explores the thermodynamic and kinematic features of easterly waves over northeast Africa in July-September season 2005-2015. A daily African easterly wave (AEW) index is formulated from transient satellite rainfall and reanalysis vorticity, and the ten most intense cases are studied by composite analysis. Surface moisture is advected from central Africa towards the Red Sea during AEW formation. The anomalous 600 hPa wind circulation is comprized of a cyclonic-south anticyclonic-north rotor pair and accentuated easterly jet along 17N. Composite convection is initiated over Ethiopia and subsequently intensifies following interaction with a zonal circulation located downstream. Composite AEW temperature anomalies reveal a cool lower-warm upper layer heating profile. 2-8 day variance of satellite OLR reaches a maximum over the southern Arabian Peninsula, suggesting an upstream role for surface heating and the Somali Jet. The large scale environment is analyzed by regression of the AEW index onto daily fields of rainfall, surface air pressure and temperature in July-September season ( N = 1004). The rainfall regression reflects a westward propagating AEW wave-train of higher values on 13N and lower values on 7N with a longitude spacing of 25°. The air pressure and temperature regression features a N-S dipole indicating an anomalous northward ITCZ. A low pressure signal west of the Maritime Continent coupled with a warm zone across the South Indian Ocean coincides with AEW formation over the eastern Sahel.

Response of eddy activities to localized diabatic heating in Held-Suarez simulations

NASA Astrophysics Data System (ADS)

Lin, Yanluan; Zhang, Jishi; Li, Xingrui; Deng, Yi

2018-01-01

Widespread air pollutions, such as black carbon over East Asia in recent years, could induce a localized diabatic heating, and thus lead to localized static stability and meridional temperature gradient (MTG) changes. Although effect of static stability and MTG on eddies has been addressed by the linear baroclinic instability theory, impacts of a localized heating on mid-latitude eddy activities have not been well explored and quantified. Via a series of idealized global Held-Suarez simulations with different magnitudes of localized heating at different altitudes and latitudes, responses of mid-latitude eddy activity and circulation to these temperature perturbations are systematically investigated. Climatologically, the localized heating in the lower atmosphere induces a wave-like response of eddy activity near the mid-latitude jet stream. Over the heating region, eddy activity tends to be weakening due to the increased static stability. However, there are cyclonic anomalies over the upstream and downstream of the heating region. The zonal mean eddy activity weakens along the baroclinic zone due to reduced MTG and increased static stability. Furthermore, the response of eddy activity increased as the heating magnitude is increased and moved to higher altitudes. The influence of the heating decreases as the heating is prescribed further away from the climatological mid-latitude jet. This implies that the localized heating is most effective over the region with the maximum baroclinicity. Besides, enhanced storm track downstream of the localized heating area found here suggests that increased aerosols over East Asia might strengthen the North Pacific storm track.

Parametric Analyses of Potential Effects on Stratospheric and Tropospheric Ozone Chemistry by a Fleet of Supersonic Business Jets Projected in a 2020 Atmosphere

NASA Technical Reports Server (NTRS)

Wey, Chowen (Technical Monitor); Dutta, M.; Patten, K.; Wuebbles, D.

2004-01-01

A class of new supersonic aircraft for business purposes is currently under consideration for use starting around 2015 to 2020. These aircraft, which can accommodate about 12 to 13 passengers, will fly at a speed of Mach 1.6 to 2 and are commonly termed as Supersonic Business Jets (SSBJs). A critical issue that needs to be addressed during the conception phase of such aircraft is the potential impact of emissions from such aircraft on the atmosphere especially on stratospheric ozone. Although these SSBJs will be much smaller in size and will have smaller engines than the hypothetical fleets of commercial passenger High Speed Civil Transport (HSCT) aircraft that we have studied previously, they will still emit nitrogen oxides (NOx = NO + NO2), carbon dioxide (CO2), water vapor (H2O) and sulfur, the latter if it is still in the fuel. Thus, it is important to design these SSBJs in a manner so that a projected fleet of these aircraft will not have a significant effect on ozone or on climate. This report analyzes the potential impact of a fleet of SSBJs in a set of parametric analyses that examine the envelope of potential effects on ozone over a range of total fuel burns, emission indices of nitrogen oxides (E.I.(NOx)), and cruise altitudes, using the current version of the UIUC zonally-averaged two-dimensional model of the global atmosphere.

Milankovitch forcing and role of Indonesian Gateway on middle Miocene climate and carbon cycle: New perspective from the South China Sea, equatorial West Pacific and East Indian Ocean

NASA Astrophysics Data System (ADS)

Holbourn, A.; Kuhnt, W.; Schulz, M.

2003-04-01

The enigmatic long-term positive carbon isotope excursion ("Monterey excursion") in the middle Miocene exhibits an apparent 400 ky cyclicity (long eccentricity cycle of the Milankovitch frequency band). Similar isotope excursion are known from the mid-Cretaceous and may be a characteristic feature of a greenhouse world with extreme warm climate, high sealevel, and a dominantly zonal circulation pattern in the world ocean. This period of extreme warmth (the mid-Miocene climate optimum) ended between 14.2 and 13.8 Ma, when a significant increase in deep-water oxygen isotopic values occurred that was related to the growth of the East Antarctic ice sheet. Plate tectonic movements between Australia and SE Asia, ultimately leading to the closure of the deep water gateway connecting the Indian and Pacific Oceans, started prior to this paleoceanographic change. We used benthic deep water oxygen and carbon isotope curves in combination with new age models at critical locations along the northern margin of the Indonesian Gateway (South China Sea, ODP Site 1146), at the western end of the gateway (NW Australian margin, ODP Site 761) and at the eastern end of the gateway (Ontong Java Plateau, ODP Site 806) to investigate the frequency and amplitude of deep water isotope fluctuations during the middle Miocene. High resolution sediment color reflectance data, benthic carbon isotopes and foraminiferal assemblages are used as proxies of deep-water ventilation and carbon flux. Our results indicate Milankovitch forcing on virtually all proxies and a change from eccentricity to precession driven cyclicity at approximately 15 Ma. Our data reveal increased carbon flux and a restricted deep water exchange between the Pacific Ocean and Indian Ocean through the Indonesian Gateway during the middle Miocene climate optimum. After 13.6 Ma, the decrease in d13C was strongest at Site 806, indicating a marked change in the deep-water circulation of the equatorial West Pacific and a switch to a more distant deep-water source.

A Madden-Julian oscillation event realistically simulated by a global cloud-resolving model.

PubMed

Miura, Hiroaki; Satoh, Masaki; Nasuno, Tomoe; Noda, Akira T; Oouchi, Kazuyoshi

2007-12-14

A Madden-Julian Oscillation (MJO) is a massive weather event consisting of deep convection coupled with atmospheric circulation, moving slowly eastward over the Indian and Pacific Oceans. Despite its enormous influence on many weather and climate systems worldwide, it has proven very difficult to simulate an MJO because of assumptions about cumulus clouds in global meteorological models. Using a model that allows direct coupling of the atmospheric circulation and clouds, we successfully simulated the slow eastward migration of an MJO event. Topography, the zonal sea surface temperature gradient, and interplay between eastward- and westward-propagating signals controlled the timing of the eastward transition of the convective center. Our results demonstrate the potential making of month-long MJO predictions when global cloud-resolving models with realistic initial conditions are used.

Alternative experiments using the geophysical fluid flow cell

NASA Technical Reports Server (NTRS)

Hart, J. E.

1984-01-01

This study addresses the possibility of doing large scale dynamics experiments using the Geophysical Fluid Flow Cell. In particular, cases where the forcing generates a statically stable stratification almost everywhere in the spherical shell are evaluated. This situation is typical of the Earth's atmosphere and oceans. By calculating the strongest meridional circulation expected in the spacelab experiments, and testing its stability using quasi-geostrophic stability theory, it is shown that strongly nonlinear baroclinic waves on a zonally symmetric modified thermal wind will not occur. The Geophysical Fluid Flow Cell does not have a deep enough fluid layer to permit useful studies of large scale planetary wave processes arising from instability. It is argued, however, that by introducing suitable meridional barriers, a significant contribution to the understanding of the oceanic thermocline problem could be made.

Time-varying zonal asymmetries in stratospheric nitrous oxide and methane

NASA Technical Reports Server (NTRS)

Gao, H.; Stanford, J. L.

1993-01-01

Previously analyses of Stratospheric And Mesospheric Sounder (SAMS) data of atmospheric constituent gases have dealt almost exclusively with zonal means (and mostly monthly means), owing perhaps to concern over data quality. The purpose of this note is to show that, with care, time-dependent zonally-asymmetric features may be recovered from the SAMS nitrous oxide and methane data. As an example, we demonstrate the existence of zonal wave-1 constituent perturbations with periods of a few weeks in the middle and upper stratosphere. When the perturbations are normalized by the constituent zonal-mean mixing ratio to compensate for the slowly varying (in both space and time) background concentration of constituents, wavepacket-like features are found over all latitudes and seasons in the three-year SAMS record. One specific low-latitude case discussed had features which appear to be consistent with constituent oscillations induced by episodic equatorial Kelvin waves. Further studies are needed to better identify the nature of the plethora of observed wave-like phenomena.

Effect of resonant magnetic perturbations on secondary structures in drift-wave turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leconte, M.; Diamond, P. H.; CMTFO and CASS, UCSD, California 92093

2011-08-15

Recent experiments showed a decrease of long range correlations during the application of resonant magnetic perturbations (RMPs) [Y. Xu et al., Nucl. Fusion 51, 063020 (2011)]. This finding suggests that RMPs damp zonal flows. To elucidate the effect of the RMPs on zonal structures in drift wave turbulence, we construct a generalized Hasegawa-Wakatani model including RMP fields. The effect of the RMPs is to induce a linear coupling between the zonal electric field and the zonal density gradient, which drives the system to a state of electron radial force balance for large RMP amplitude. A predator-prey model coupling the primarymore » drift wave dynamics to the zonal modes evolution is derived. This model has both turbulence drive and RMP amplitude as control parameters and predicts a novel type of transport bifurcation in the presence of RMPs. The novel regime has a power threshold which increases with RMP amplitude as {gamma}{sub c}{approx}[({delta}B{sub r}/B)]{sup 2}.« less

The modulational instability in the extended Hasegawa-Mima equation with a finite Larmor radius

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gallagher, S.; Hnat, B.; Rowlands, G.

2012-12-15

The effects of the finite Larmor radius on the generation of zonal flows by the four-wave modulational instability are investigated using an extended form of the Hasegawa-Mima equation. Growth rates of the zonal mode are quantified using analytical predictions from a four-mode truncated model, as well as from direct numerical simulation of the nonlinear extended Hasegawa-Mima equation. We not only consider purely zonal flows but also examine the generic oblique case and show that, for small Larmor radii, off-axis modes may become dominant. We find a key parameter M{sub {rho}} which characterises the behaviour of the system due to changesmore » in the Larmor radius. We find that, similarly to previous results obtained by changing the driving wave amplitude, two separate dynamical regimes can be accessed. These correspond to oscillatory energy transfer between zonal flows and a driving wave and the fully saturated zonal flow.« less

Gravitational Anomalies Caused by Zonal Winds in Jupiter

NASA Astrophysics Data System (ADS)

Schubert, G.; Kong, D.; Zhang, K.

2012-12-01

We present an accurate three-dimensional non-spherical numerical calculation of the gravitational anomalies caused by zonal winds in Jupiter. The calculation is based on a three-dimensional finite element method and accounts for the full effect of significant departure from spherical geometry caused by rapid rotation. Since the speeds of Jupiter's zonal winds are much smaller than that of its rigid-body rotation, our numerical calculation is carried out in two stages. First, we compute the non-spherical distributions of density and pressure at the equilibrium within Jupiter via a hybrid inverse approach by determining an a priori unknown coefficient in the polytropic equation of state that results in a match to the observed shape of Jupiter. Second, by assuming that Jupiter's zonal winds extend throughout the interior along cylinders parallel to the rotation axis, we compute gravitational anomalies produced by the wind-related density anomalies, providing an upper bound to the gravitational anomalies caused by the Jovian zonal winds.

Zonally Asymmetric Ozone and the Morphology of the Planetary Waveguide

DTIC Science & Technology

2011-07-15

sections for the 271 troposphere , J. Atmos. Sci., 37, 2600-2616. 272 Eyring, V., et al. (2007), Multimodel projections of stratospheric ozone ...GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/, JULY 15, 2011 Zonally asymmetric ozone and the morphology of the 1 planetary waveguide...that zonally asymmetric 6 ozone (ZAO) profoundly changes the morphology of the Northern Hemisphere planetary 7 waveguide (PWG). ZAO causes the PWG to

The role of zonal flows in the saturation of multi-scale gyrokinetic turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Staebler, G. M.; Candy, J.; Howard, N. T.

2016-06-15

The 2D spectrum of the saturated electric potential from gyrokinetic turbulence simulations that include both ion and electron scales (multi-scale) in axisymmetric tokamak geometry is analyzed. The paradigm that the turbulence is saturated when the zonal (axisymmetic) ExB flow shearing rate competes with linear growth is shown to not apply to the electron scale turbulence. Instead, it is the mixing rate by the zonal ExB velocity spectrum with the turbulent distribution function that competes with linear growth. A model of this mechanism is shown to be able to capture the suppression of electron-scale turbulence by ion-scale turbulence and the thresholdmore » for the increase in electron scale turbulence when the ion-scale turbulence is reduced. The model computes the strength of the zonal flow velocity and the saturated potential spectrum from the linear growth rate spectrum. The model for the saturated electric potential spectrum is applied to a quasilinear transport model and shown to accurately reproduce the electron and ion energy fluxes of the non-linear gyrokinetic multi-scale simulations. The zonal flow mixing saturation model is also shown to reproduce the non-linear upshift in the critical temperature gradient caused by zonal flows in ion-scale gyrokinetic simulations.« less

Future Effects of Southern Hemisphere Stratospheric Zonal Asymmetries on Climate

NASA Astrophysics Data System (ADS)

Stone, K.; Solomon, S.; Kinnison, D. E.; Fyfe, J. C.

2017-12-01

Stratospheric zonal asymmetries in the Southern Hemisphere have been shown to have significant influences on both stratospheric and tropospheric dynamics and climate. Accurate representation of stratospheric ozone in particular is important for realistic simulation of the polar vortex strength and temperature trends. This is therefore also important for stratospheric ozone change's effect on the troposphere, both through modulation of the Southern Annular Mode (SAM), and more localized climate. Here, we characterization the impact of future changes in Southern Hemisphere zonal asymmetry on tropospheric climate, including changes to future tropospheric temperature, and precipitation. The separate impacts of increasing GHGs and ozone recovery on the zonal asymmetric influence on the surface are also investigated. For this purpose, we use a variety of models, including Chemistry Climate Model Initiative simulations from the Community Earth System Model, version 1, with the Whole Atmosphere Community Climate Model (CESM1(WACCM)) and the Australian Community Climate and Earth System Simulator-Chemistry Climate Model (ACCESS-CCM). These models have interactive chemistry and can therefore more accurately represent the zonally asymmetric nature of the stratosphere. The CESM1(WACCM) and ACCESS-CCM models are also compared to simulations from the Canadian Can2ESM model and CESM-Large Ensemble Project (LENS) that have prescribed ozone to further investigate the importance of simulating stratospheric zonal asymmetry.

The role of zonal flows in the saturation of multi-scale gyrokinetic turbulence

DOE PAGES

Staebler, Gary M.; Candy, John; Howard, Nathan T.; ...

2016-06-29

The 2D spectrum of the saturated electric potential from gyrokinetic turbulence simulations that include both ion and electron scales (multi-scale) in axisymmetric tokamak geometry is analyzed. The paradigm that the turbulence is saturated when the zonal (axisymmetic) ExB flow shearing rate competes with linear growth is shown to not apply to the electron scale turbulence. Instead, it is the mixing rate by the zonal ExB velocity spectrum with the turbulent distribution function that competes with linear growth. A model of this mechanism is shown to be able to capture the suppression of electron-scale turbulence by ion-scale turbulence and the thresholdmore » for the increase in electron scale turbulence when the ion-scale turbulence is reduced. The model computes the strength of the zonal flow velocity and the saturated potential spectrum from the linear growth rate spectrum. The model for the saturated electric potential spectrum is applied to a quasilinear transport model and shown to accurately reproduce the electron and ion energy fluxes of the non-linear gyrokinetic multi-scale simulations. Finally, the zonal flow mixing saturation model is also shown to reproduce the non-linear upshift in the critical temperature gradient caused by zonal flows in ionscale gyrokinetic simulations.« less

The possible physical mechanism for the EAP-SR co-action

NASA Astrophysics Data System (ADS)

Gong, Zhiqiang; Feng, Guolin; Dogar, Muhammad Mubashar; Huang, Gang

2017-11-01

The anomalous characteristics of summer precipitation and atmospheric circulation in the East Asia-West Pacific Region (EA-WP) associated with the co-action of East Asia/Pacific teleconnection-Silk Road teleconnection (EAP-SR) are investigated in this study. The compositions of EAP-SR phase anomalies can be expressed as pattern I (+ +), pattern II (+ -), pattern III (- -), and pattern IV (- +) using EAP and SR indices. It is found that the spatial distribution of summer precipitation anomalies in EA-WP corresponding to pattern I (III) shows a tripole structure in the meridional direction and a zonal dipole structure in the subtropical region, while pattern II (IV) presents a tripole pattern in meridional direction with compressed and continuous anomalies in the zonal direction over the subtropical region. The similar meridional and zonal structures are also found in the geopotential height anomalies at 500-hPa, as well as wind anomalies and moisture convergence at 850-hPa. Finally, a schematic mechanism for the EAP-SR co-action upon the summer precipitation in EA-WP is built: (1) Pattern I (III) exhibits that the negative (positive) sea surface temperature (SST) anomalies over tropical East Pacific may cause the enhanced (weakened) convective activity dominating the West Pacific, trigger the positive (negative) EAP teleconnection and produce more (less) precipitation. Besides, the negative (positive) SST anomalies over the Indonesia Maritime Continent (IMC) may further weaken (strengthen) anomalous downward (upward) motion over the South China Sea (SCS), cause negative (positive) geopotential height anomalies at the middle troposphere and surrounding regions through the function of the tropical Hadley circulation. Then the negative (positive) geopotential height anomalies could motivate the positive (negative) EAP teleconnection through the northward propagation of wave-activity perturbation. Meanwhile, a positive (negative) geopotential height anomalous pattern over Eastern Europe motivates a Rossby wave train propagation from Western Europe to west-central Asia. This circumstance can cause suppressed (enhanced) convection and less (more) precipitation over northwestern India and Pakistan, which could strengthen the negative (positive) geopotential height and positive (negative) vorticity anomalies over central East Asia, resulting in a negative (positive) SR teleconnection along the Asian jet stream. A positive (negative) lobe over the Korean Peninsula and Japan corresponding to SR overlaps with a positive (negative) lobe of EAP, which strengthens the anomalous phase contrast on both sides of 120°E. Accordingly, summer precipitation anomalies in EA-WP exhibit the meridional tripole pattern and the zonal dipole pattern. (2) Pattern II (IV) indicates that the normal SST anomalies over the tropical East Pacific cause the weak tele-impact on the tropical West Pacific, while the positive (negative) SST anomalies over the IMC will lead to a negative (positive) lobe of EAP over the subtropical region. This circumstance can weaken the positive (negative) lobe of SR over subtropical region, causing compressed and continuous negative (positive) anomalies of 500-hPa geopotential height and positive (negative) surface precipitation anomalies from central East China to Japan.

First Production of C60 Nanoparticle Plasma Jet for Study of Disruption Mitigation for ITER

NASA Astrophysics Data System (ADS)

Bogatu, I. N.; Thompson, J. R.; Galkin, S. A.; Kim, J. S.; Brockington, S.; Case, A.; Messer, S. J.; Witherspoon, F. D.

2012-10-01

Unique fast response and large mass-velocity delivery of nanoparticle plasma jets (NPPJs) provide a novel application for ITER disruption mitigation, runaway electrons diagnostics and deep fueling. NPPJs carry a much larger mass than usual gases. An electromagnetic plasma gun provides a very high injection velocity (many km/s). NPPJ has much higher ram pressure than any standard gas injection method and penetrates the tokamak confining magnetic field. Assimilation is enhanced due to the NP large surface-to-volume ratio. Radially expanding NPPJs help achieving toroidal uniformity of radiation power. FAR-TECH's NPPJ system was successfully tested: a coaxial plasma gun prototype (˜35 cm length, 96 kJ energy) using a solid state TiH2/C60 pulsed power cartridge injector produced a hyper-velocity (>4 km/s), high-density (>10^23 m-3), C60 plasma jet in ˜0.5 ms, with ˜1-2 ms overall response-delivery time. We present the TiH2/C60 cartridge injector output characterization (˜180 mg of sublimated C60 gas) and first production results of a high momentum C60 plasma jet (˜0.6 g.km/s).

Influence of oxygen in atmospheric-pressure argon plasma jet on sterilization of Bacillus atrophaeous spores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Jin-Pyo; Uhm, Han S.; Li, Shou-Zhe

2007-09-15

A nonequilibrium Ar/O{sub 2} plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56 MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as freemore » from toxic biological warfare agents. The decimal reduction time (D values) of the Ar/O{sub 2} plasma jet at an exposure distance of 0.5-1.5 cm ranges from 5 to 57 s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.« less

A nonlinear self-similar solution to barotropic flow over rapidly varying topography

NASA Astrophysics Data System (ADS)

Ibanez, Ruy; Kuehl, Joseph

2016-11-01

Beginning from the Shallow Water Equations (SWE), a nonlinear self-similar analytic solution is derived for barotropic flow over rapidly varying topography. We study conditions relevant to the ocean slope where the flow is dominated by Earth's rotation and topography. Attention is paid to the northern Gulf of Mexico slope with application to pollutant dispersion and the Norwegian Coastal Current which sheds eddies into the Lofoten Basin that are believe to influence deep water formation. The solution is found to extend the topographic β-plume solution (Kuehl 2014, GRL) in two ways: 1) The solution is valid for intensifying jets. 2) The influence of nonlinear advection is included. The SWE are scaled to the case of a topographically controlled jet, then solved by introducing a similarity variable η = Cxy . The nonlinear solution, valid for topographies h =h0 - αxy3 , takes the form of the Lambert W Function for velocity. The linear solution, valid for topographies h =h0 - αxyγ , takes the form of the Error Function for transport. Kuehl's results considered the case - 1 <= γ < 1 which admits expanding jets, while the new result consider the case γ < - 1 which admits intensifying jets.

Rethinking wave-kinetic theory applied to zonal flows

NASA Astrophysics Data System (ADS)

Parker, Jeffrey

2017-10-01

Over the past two decades, a number of studies have employed a wave-kinetic theory to describe fluctuations interacting with zonal flows. Recent work has uncovered a defect in this wave-kinetic formulation: the system is dominated by the growth of (arbitrarily) small-scale zonal structures. Theoretical calculations of linear growth rates suggest, and nonlinear simulations confirm, that this system leads to the concentration of zonal flow energy in the smallest resolved scales, irrespective of the numerical resolution. This behavior results from the assumption that zonal flows are extremely long wavelength, leading to the neglect of key terms responsible for conservation of enstrophy. A corrected theory, CE2-GO, is presented; it is free of these errors yet preserves the intuitive phase-space mathematical structure. CE2-GO properly conserves enstrophy as well as energy, and yields accurate growth rates of zonal flow. Numerical simulations are shown to be well-behaved and not dependent on box size. The steady-state limit simplifies into an exact wave-kinetic form which offers the promise of deeper insight into the behavior of wavepackets. The CE2-GO theory takes its place in a hierarchy of models as the geometrical-optics reduction of the more complete cumulant-expansion statistical theory CE2. The new theory represents the minimal statistical description, enabling an intuitive phase-space formulation and an accurate description of turbulence-zonal flow dynamics. This work was supported by an NSF Graduate Research Fellowship, a US DOE Fusion Energy Sciences Fellowship, and US DOE Contract Nos. DE-AC52-07NA27344 and DE-AC02-09CH11466.

Layered virus protection for the operations and administrative messaging system

NASA Technical Reports Server (NTRS)

Cortez, R. H.

2002-01-01

NASA's Deep Space Network (DSN) is critical in supporting the wide variety of operating and plannedunmanned flight projects. For day-to-day operations it relies on email communication between the three Deep Space Communication Complexes (Canberra, Goldstone, Madrid) and NASA's Jet Propulsion Laboratory. The Operations & Administrative Messaging system, based on the Microsoft Windows NTand Exchange platform, provides the infrastructure that is required for reliable, mission-critical messaging. The reliability of this system, however, is threatened by the proliferation of email viruses that continue to spread at alarming rates. A layered approach to email security has been implemented across the DSN to protect against this threat.

The JPL Resource Allocation Planning and Scheduling Office (RAPSO) process

NASA Technical Reports Server (NTRS)

Morris, D. G.; Burke, E. S.

2002-01-01

The Jet Propulsion Laboratory's Resource Allocation Planning and Scheduling Office is chartered to divide the limited amount of tracking hours of the Deep Space Network amongst the various missions in as equitable allotment as can be achieved. To best deal with this division of assets and time, an interactive process has evolved that promotes discussion with agreement by consensus between all of the customers that use the Deep Space Network (DSN). Aided by a suite of tools, the task of division of asset time is then performed in three stages of granularity. Using this approach, DSN loads are either forecasted or scheduled throughout a moving 10-year window.

DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2013-01-01

The meteorology of hot Jupiters has been characterized primarily with thermal measurements, but recent observations suggest the possibility of directly detecting the winds by observing the Doppler shift of spectral lines seen during transit. Motivated by these observations, we show how Doppler measurements can place powerful constraints on the meteorology. We show that the atmospheric circulation-and Doppler signature-of hot Jupiters splits into two regimes. Under weak stellar insolation, the day-night thermal forcing generates fast zonal jet streams from the interaction of atmospheric waves with the mean flow. In this regime, air along the terminator (as seen during transit) flows towardmore » Earth in some regions and away from Earth in others, leading to a Doppler signature exhibiting superposed blueshifted and redshifted components. Under intense stellar insolation, however, the strong thermal forcing damps these planetary-scale waves, inhibiting their ability to generate jets. Strong frictional drag likewise damps these waves and inhibits jet formation. As a result, this second regime exhibits a circulation dominated by high-altitude, day-to-night airflow, leading to a predominantly blueshifted Doppler signature during transit. We present state-of-the-art circulation models including non-gray radiative transfer to quantify this regime shift and the resulting Doppler signatures; these models suggest that cool planets like GJ 436b lie in the first regime, HD 189733b is transitional, while planets hotter than HD 209458b lie in the second regime. Moreover, we show how the amplitude of the Doppler shifts constrains the strength of frictional drag in the upper atmospheres of hot Jupiters. If due to winds, the {approx}2 km s{sup -1} blueshift inferred on HD 209458b may require drag time constants as short as 10{sup 4}-10{sup 6} s, possibly the result of Lorentz-force braking on this planet's hot dayside.« less

A western boundary current east of New Caledonia: Observed characteristics

NASA Astrophysics Data System (ADS)

Gasparin, Florent; Ganachaud, Alexandre; Maes, Christophe

2011-09-01

Waters from the South Equatorial Current (SEC), the northern branch of the South Pacific subtropical gyre, are a major supply of heat to the equatorial warm pool, and have an important contribution to climate variability and ENSO which motivated the Southwest Pacific Ocean and Climate Experiment (SPICE, CLIVAR/WCRP). Initially a broad westward current extending from the equator to 30°S, the SEC splits upon arriving at the major islands and archipelagoes of Fiji (18°S, 180°E), Vanuatu (16°S, 168°E), and New Caledonia (22°S, 165°E), resulting in a complex system of western boundary currents and zonal jets that feed the Coral and Solomon Seas. We focus here on the formation of one specific jet feeding the Coral Sea, the North Caledonian Jet (NCJ). Using a combination of recent oceanographic cruises, we describe the ocean circulation to the northeast of New Caledonia, where the SEC forms a western boundary current that ultimately becomes the NCJ. This current, which we document for the first time and propose to refer to as the East Caledonian Current (ECC), has its core located 10-100 km off the east coast of New Caledonia, and extends vertically to at least 1000 m depth. Water mass properties show continuous westward transports through the ECC, from the SEC to the NCJ in both the South Pacific Tropical Waters in the thermocline and Antarctic Intermediate Waters near 700 m depth. The ECC extends about 100 km horizontally; its average 0-1000 m transport was estimated at 14.5±3 Sv off the north tip of the New Caledonian reef, with a maximum of 20 Sv in May 2010. South of that the upstream branch of the ECC east of the Loyalty is close to 8 Sv suggesting an important additional contribution from central Pacific waters carried by the SEC at 16°S and diverted to our region through the western boundary current system east of Vanuatu.

KSC-04PD-2404

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. On Launch Pad 17-B, Cape Canaveral Air Force Station, Fla., a second Solid Rocket Booster (SRB) is raised off a transporter to be lifted up the mobile service tower. It will be attached to the Boeing Delta II launch vehicle for launch of the Deep Impact spacecraft. A NASA Discovery mission, Deep Impact will probe beneath the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth, and reveal the secrets of its interior. After releasing a 3- by 3-foot projectile to crash onto the surface, Deep Impacts flyby spacecraft will collect pictures and data of how the crater forms, measuring the craters depth and diameter, as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. It will send the data back to Earth through the antennas of the Deep Space Network. Deep Impact project management is handled by the Jet Propulsion Laboratory in Pasadena, Calif. The spacecraft is scheduled to launch Dec. 30, 2004.

Deep Impact Spacecraft Collides With Comet Tempel 1 (Video)

NASA Technical Reports Server (NTRS)

2005-01-01

After 172 days and 268 million miles of deep space travel, the NASA Deep Impact spacecraft successfully reached out and touched comet Tempel 1. The collision between the coffee table-sized space probe and city-sized comet occurred July 4, 2005 at 12:52 a.m. CDT. Comprised of images taken by the targeting sensor aboard the impactor probe, this movie shows the spacecraft approaching the comet up to just seconds before impact. Mission scientists expect Deep Impact to provide answers to basic questions about the formation of the solar system. Principal investigator for Deep Impact, Dr. Michael A'Hearn of the University of Maryland in College Park, is responsible for the mission, and project management is handled by the Jet Propulsion Laboratory in Pasadena, California. The program office at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama assisted the Science Mission Directorate at NASA Headquarters in Washington with program management, technology planning, systems assessment, flight assurance and public outreach. The spacecraft was built for NASA by Ball Aerospace & Technologies Corporation of Boulder, Colorado. (NASA/JPL-Caltech/UMD)

Role of Atmospheric Circulation and Westerly Jet Changes in the mid-Holocene East Asian Summer Monsoon

NASA Astrophysics Data System (ADS)

Kong, W.; Chiang, J. C. H.

2014-12-01

The East Asian Summer Monsoon (EASM) varies on inter-decadal to interglacial-glacial timescales. The EASM is stronger in the mid-Holocene than today, and these changes can be readily explained by orbitally-driven insolation increase during the boreal summer. However, a detailed understanding of the altered seasonal evolution of the EASM during this time is still lacking. In particular, previous work has suggested a close link between seasonal migration of the EASM and that of the mid-latitude westerlies impinging on the Tibetan Plateau. In this study, we explore, this problem in PMIP3 climate model simulations of the mid-Holocene, focusing on the role of atmospheric circulation and in particular how the westerly jet modulates the East Asia summer climate on paleoclimate timescales. Analysis of the model simulations suggests that, compared to the preindustrial simulations, the transition from Mei-Yu to deep summer rainfall occurs earlier in the mid-Holocene. This is accompanied by an earlier weakening and northward shift of westerly jet away from the Tibetan Plateau. The variation in the strength and the 3-D structure of the westerly jet in the mid-Holocene is summarized. We find that changes to the monsoonal rainfall, westerly jet and meridional circulation covary on paleoclimate timescales. Meridional wind changes in particular are tied to an altered stationary wave pattern, resembling today's the so-called 'Silk Road' teleconnection pattern, riding along the westerly jet. Diagnostic analysis also reveals changes in moist static energy and eddy energy fluxes associated with the earlier seasonal transition of the EASM. Our analyses suggest that the westerly jet is critical to the altered dynamics of the East Asian summer monsoon during the mid-Holocene.

The Jet/Disk Connection in AGN: Chandra and XMM-Newton Observations of Three Powerful Radio-Loud Quasars

NASA Technical Reports Server (NTRS)

Sambruna, Rita; Gliozzi, Mario; Tavecchio, F.; Maraschi, L.; Foschini, Luigi

2007-01-01

The connection between the accretion process that powers AGN and the formation of jets is still poorly understood. Here we tackle this issue using new, deep Chandra and XMM-Newton observations of tlie cores of three powerful radio loud quasars: 1136-135, 1150+497 (Chandra), and 0723+679 (XMM-Newton), in the redshift range z=0.3-0.8. These sources are known from our previous Chandra siiapsliot survey to liave kpc-scale X-ray jets. In 1136-135 and 1150-1+497; evidence is found for the presence of diffuse thermal X-ray emission around the cores; on scales of 40-50 kpc and with luminosity L(sub 0.3-2 kev approx. 10(sup 43) erg per second, suggesting thermal emission from the host galaxy or a galaxy group. The X-ray continua of the cores in the three sources are described by an upward-curved (concave) broken power law, with photon indices GAMMA (sub soft) approx. 1.8 - 2.1 and GAMMA (sub hard) approx. 1.7 below and above approx. equal to 2 keV, respectively. There is evidence for an uiiresolved Fe K alpha line with EW approx. 70 eV in the three quasars. The Spectral Energy Distributions of the sources can be well described by a mix of jet and disk emission, with the jet dominating the radio and hard X-rays (via synchrotron and external Compton) and the disk dominating the optical/UV through soft X-rays. The ratio of the jet-to-disk powers is approx. 1, consistent with those derived for a number of gamma ray emitting blazars. This indicates that near equality of accretion and jet power may be common in powerful radio-loud AGN.

KSC-05PD-0113

NASA Technical Reports Server (NTRS)

2005-01-01

JET PROPULSION LABORATORY, CALIF. At Ball Aerospace in Boulder, Colo., the infrared (IR) spectrometer for the Deep Impact flyby spacecraft is inspected in the instrument assembly area in the Fisher Assembly building clean room. Deep Impact will probe beneath the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth, and reveal the secrets of its interior. After releasing a 3- by 3-foot projectile to crash onto the surface, Deep Impacts flyby spacecraft will collect pictures and data of how the crater forms, measuring the craters depth and diameter, as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. The spectrometer is part of the High Resolution Instrument in the spacecraft. This imager will be aimed at the ejected matter as the crater forms, and an infrared 'fingerprint' of the material from inside of the comet's nucleus will be taken. It will send the data back to Earth through the antennas of the Deep Space Network. Deep Impact is a NASA Discovery mission. Launch of Deep Impact is scheduled for Jan. 12 from Launch Pad 17-B, Cape Canaveral Air Force Station, Fla.

A flexible climate model for use in integrated assessments

NASA Astrophysics Data System (ADS)

Sokolov, A. P.; Stone, P. H.

Because of significant uncertainty in the behavior of the climate system, evaluations of the possible impact of an increase in greenhouse gas concentrations in the atmosphere require a large number of long-term climate simulations. Studies of this kind are impossible to carry out with coupled atmosphere ocean general circulation models (AOGCMs) because of their tremendous computer resource requirements. Here we describe a two dimensional (zonally averaged) atmospheric model coupled with a diffusive ocean model developed for use in the integrated framework of the Massachusetts Institute of Technology (MIT) Joint Program on the Science and Policy of Global Change. The 2-D model has been developed from the Goddard Institute for Space Studies (GISS) GCM and includes parametrizations of all the main physical processes. This allows it to reproduce many of the nonlinear interactions occurring in simulations with GCMs. Comparisons of the results of present-day climate simulations with observations show that the model reasonably reproduces the main features of the zonally averaged atmospheric structure and circulation. The model's sensitivity can be varied by changing the magnitude of an inserted additional cloud feedback. Equilibrium responses of different versions of the 2-D model to an instantaneous doubling of atmospheric CO2 are compared with results of similar simulations with different AGCMs. It is shown that the additional cloud feedback does not lead to any physically inconsistent results. On the contrary, changes in climate variables such as precipitation and evaporation, and their dependencies on surface warming produced by different versions of the MIT 2-D model are similar to those shown by GCMs. By choosing appropriate values of the deep ocean diffusion coefficients, the transient behavior of different AOGCMs can be matched in simulations with the 2-D model, with a unique choice of diffusion coefficients allowing one to match the performance of a given AOGCM for a variety of transient forcing scenarios. Both surface warming and sea level rise due to thermal expansion of the deep ocean in response to a gradually increasing forcing are reasonably reproduced on time scales of 100-150 y. However a wide range of diffusion coefficients is needed to match the behavior of different AOGCMs. We use results of simulations with the 2-D model to show that the impact on climate change of the implied uncertainty in the rate of heat penetration into the deep ocean is comparable with that of other significant uncertainties.

Inventory of File sref.t03z.pgrb212_SPC.prob_1hrly.grib2

Science.gov Websites

analysis Total Precipitation [prob] prob >0.25 002 cloud base U-GWD 1 hour fcst Zonal Flux of Gravity Precipitation [prob] prob >0.25 007 cloud base U-GWD 2 hour fcst Zonal Flux of Gravity Wave Stress [prob ;0.25 012 cloud base U-GWD 4 hour fcst Zonal Flux of Gravity Wave Stress [prob] prob =1 013 entire

Involving Scientists in the NASA / JPL Solar System Educators Program

NASA Astrophysics Data System (ADS)

Brunsell, E.; Hill, J.

2001-11-01

The NASA / JPL Solar System Educators Program (SSEP) is a professional development program with the goal of inspiring America's students, creating learning opportunities, and enlightening inquisitive minds by engaging them in the Solar System exploration efforts conducted by the Jet Propulsion Laboratory (JPL). SSEP is a Jet Propulsion Laboratory program managed by Space Explorers, Inc. (Green Bay, WI) and the Virginia Space Grant Consortium (Hampton, VA). The heart of the program is a large nationwide network of highly motivated educators. These Solar System Educators, representing more than 40 states, lead workshops around the country that show teachers how to successfully incorporate NASA materials into their teaching. During FY2001, more than 9500 educators were impacted through nearly 300 workshops conducted in 43 states. Solar System Educators attend annual training institutes at the Jet Propulsion Laboratory during their first two years in the program. All Solar System Educators receive additional online training, materials and support. The JPL missions and programs involved in SSEP include: Cassini Mission to Saturn, Galileo Mission to Jupiter, STARDUST Comet Sample Return Mission, Deep Impact Mission to a Comet, Mars Exploration Program, Outer Planets Program, Deep Space Network, JPL Space and Earth Science Directorate, and the NASA Office of Space Science Solar System Exploration Education and Public Outreach Forum. Scientists can get involved with this program by cooperatively presenting at workshops conducted in their area, acting as a content resource or by actively mentoring Solar System Educators. Additionally, SSEP will expand this year to include other missions and programs related to the Solar System and the Sun.

Goldstone Tracking the Echo Satelloon.

NASA Image and Video Library

2016-10-27

This archival image was released as part of a gallery comparing JPL’s past and present, commemorating the 80th anniversary of NASA’s Jet Propulsion Laboratory on Oct. 31, 2016. This photograph shows the first pass of Echo 1, NASA's first communications satellite, over the Goldstone Tracking Station managed by NASA's Jet Propulsion Laboratory, in Pasadena, California, in the early morning of Aug. 12, 1960. The movement of the antenna, star trails (shorter streaks), and Echo 1 (the long streak in the middle) are visible in this image. Project Echo bounced radio signals off a 10-story-high, aluminum-coated balloon orbiting the Earth. This form of "passive" satellite communication -- which mission managers dubbed a "satelloon" -- was an idea conceived by an engineer from NASA's Langley Research Center in Hampton, Virginia, and was a project managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland. JPL's role involved sending and receiving signals through two of its 85-foot-diameter (26-meter-diameter) antennas at the Goldstone Tracking Station in California's Mojave Desert. The Goldstone station later became part of NASA's Deep Space Network. JPL, a division of Caltech in Pasadena, California, manages the Deep Space Network for NASA. http://photojournal.jpl.nasa.gov/catalog/PIA21114

TGLF Recalibration for ITER Standard Case Parameters FY2015: Theory and Simulation Performance Target Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Candy, J.

2015-12-01

This work was motivated by the observation, as early as 2008, that GYRO simulations of some ITER operating scenarios exhibited nonlinear zonal-flow generation large enough to effectively quench turbulence inside r /a ~ 0.5. This observation of flow-dominated, low-transport states persisted even as more accurate and comprehensive predictions of ITER profiles were made using the state-of-the-art TGLF transport model. This core stabilization is in stark contrast to GYRO-TGLF comparisons for modern-day tokamaks, for which GYRO and TGLF are typically in very close agreement. So, we began to suspect that TGLF needed to be generalized to include the effect of zonal-flowmore » stabilization in order to be more accurate for the conditions of reactor simulations. While the precise cause of the GYRO-TGLF discrepancy for ITER parameters was not known, it was speculated that closeness to threshold in the absence of driven rotation, as well as electromagnetic stabilization, created conditions more sensitive the self-generated zonal-flow stabilization than in modern tokamaks. Need for nonlinear zonal-flow stabilization: To explore the inclusion of a zonal-flow stabilization mechanism in TGLF, we started with a nominal ITER profile predicted by TGLF, and then performed linear and nonlinear GYRO simulations to characterize the behavior at and slightly above the nominal temperature gradients for finite levels of energy transport. Then, we ran TGLF on these cases to see where the discrepancies were largest. The predicted ITER profiles were indeed near to the TGLF threshold over most of the plasma core in the hybrid discharge studied (weak magnetic shear, q > 1). Scanning temperature gradients above the TGLF power balance values also showed that TGLF overpredicted the electron energy transport in the low-collisionality ITER plasma. At first (in Q3), a model of only the zonal-flow stabilization (Dimits shift) was attempted. Although we were able to construct an ad hoc model of the zonal flows that fit the GYRO simulations, the parameters of the model had to be tuned to each case. A physics basis for the zonal flow model was lacking. Electron energy transport at short wavelength: A secondary issue – the high-k electron energy flux – was initially assumed to be independent of the zonal flow effect. However, detailed studies of the fluctuation spectra from recent multiscale (electron and ion scale) GYRO simulations provided a critical new insight into the role of zonal flows. The multiscale simulations suggested that advection by the zonal flows strongly suppressed electron-scale turbulence. Radial shear of the zonal E×B fluctuation could not compete with the large electron-scale linear growth rate, but the k x-mixing rate of the E×B advection could. This insight led to a preliminary new model for the way zonal flows saturate both electron- and ion-scale turbulence. It was also discovered that the strength of the zonal E×B velocity could be computed from the linear growth rate spectrum. The new saturation model (SAT1), which replaces the original model (SAT0), was fit to the multiscale GYRO simulations as well as the ion-scale GYRO simulations used to calibrate the original SAT0 model. Thus, SAT1 captures the physics of both multiscale electron transport and zonal-flow stabilization. In future work, the SAT1 model will require significant further testing and (expensive) calibration with nonlinear multiscale gyrokinetic simulations over a wider variety of plasma conditions – certainly more than the small set of scans about a single C-Mod L-mode discharge. We believe the SAT1 model holds great promise as a physics-based model of the multiscale turbulent transport in fusion devices. Correction to ITER performance predictions: Finally, the impact of the SAT1model on the ITER hybrid case is mixed. Without the electron-scale contribution to the fluxes, the Dimits shift makes a significant improvement in the predicted fusion power as originally posited. Alas, including the high-k electron transport reduces the improvement, yielding a modest net increase in predicted fusion power compared to the TGLF prediction with the original SAT0 model.« less

Zonal disintegration of rocks around underground workings. Part II. Rock fracture simulated in equivalent materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shemyakin, E.I.; Fisenko, G.L.; Kurlenya, M.V.

1987-05-01

For a detailed testing of the effects discovered in situ, analysis of the patterns and origination conditions of fractured rock zones inside the bed around workings, and ways explosions affect the surrounding rocks, a program and a method of study on models of equivalent materials have been developed. The method of simulation on two- and three-dimensional models involved building in a solid or fissured medium a tunnel of a circular or arched cross section. The tests were done for elongate adit-type workings. At the first stage, three models were tested with different working support systems: anchor supports, concrete-spray supports andmore » no supports. Zone formation is shown and described. Tests were continued on two groups of three-dimensional models to bring the model closer to in situ conditions. The presence of gaping cracks and heavily fractured zones deep in the interior of the bed with a quasicylindrical symmetry indicates that the common views concerning the stressed-strained state of rocks around underground workings are at variance with the actual patterns of deformation and destruction of rocks near the workings in deep horizons.« less

Long term variabilities and tendencies of mesospheric lunar semidiurnal tide over Tirunelveli (8.7°N, 77.8°E)

NASA Astrophysics Data System (ADS)

Sathishkumar, S.; Sridharan, S.; Muhammed Kutty, P. V.; Gurubaran, S.

2017-10-01

The medium frequency radar deployed at Tirunelveli (8.7°N, 77.8°E), which is located near the southmost tip of peninsular India, have been providing continuous data from the year 1993 to the year 2012 that helped to study the long term tendencies in the lunar tidal variabilities over this geographic location. In the present paper we present the results of seasonal, interannual and long-term variabilities of lunar semi-diurnal tides in the upper mesosphere over Tirunelveli. The present study also includes comparison with model values. The study shows that the tidal amplitudes are larger in the meridional components of the mesospheric winds than the zonal winds. The seasonal variations of the tides are similar in both the components. The tides show maximum amplitudes of about ∼5 m/s in February/March, secondary maximum amplitudes of about ∼3 m/s in September and minimum amplitudes during summer months (May-August). The observed seasonal variation of the lunar tides do not compare well with Vial and Forbes (1994) model values, though it is consistent with earlier observations. The lunar tidal phase in meridional winds leads that in zonal winds from January to June and from September to November, while the latter leads the former during July/August. The lunar tides show large interannual variability. There are unusual amplitude enhancements in the lunar tide in meridional winds during the winters of 2006 and 2009, when major sudden stratospheric warmings (SSW) occurred at high latitude northern hemisphere, whereas zonal lunar tide does not show any clear association with the SSW. Vertical wavelengths of lunar tides in zonal and meridional wind are in the range of 20-90 km. The vertical wavelengths of lunar tides in both zonal and meridional component are smaller in June and larger in November and December. The monthly mean zonal and meridional winds are subjected to regression analysis to study the tidal response to long-period oscillations, namely, quasi-biennial oscillation (QBO), solar cycle variation and El-nino southern oscillation (ENSO). It is found the lunar tide in both zonal and meridional winds show significant QBO response, whereas zonal tide only shows significant negative response to solar cycle and positive response to ENSO. Besides, zonal tide only shows significant long-term increasing trend.

Seasonal Variability of Saturn's Tropospheric Temperatures, Winds and Para-H2 from Cassini Far-IR Spectroscopy

NASA Technical Reports Server (NTRS)

Fletcher, Leigh N.; Irwin, P. G. J; Achterberg, R. K.; Orton, G. S.; Flasar, F. M.

2015-01-01

Far-IR 16-1000 micrometer spectra of Saturn's hydrogen-helium continuum measured by Cassini's Composite Infrared Spectrometer (CIRS) are inverted to construct a near-continuous record of upper tropospheric (70-700 mbar) temperatures and para-H2 fraction as a function of latitude, pressure and time for a third of a saturnian year (2004-2014, from northern winter to northern spring). The thermal field reveals evidence of reversing summertime asymmetries superimposed onto the belt/zone structure. The temperature structure is almost symmetric about the equator by 2014, with seasonal lag times that increase with depth and are qualitatively consistent with radiative climate models. Localised heating of the tropospheric hazes (100-250 mbar) create a distinct perturbation to the temperature profile that shifts in magnitude and location, declining in the autumn hemisphere and growing in the spring. Changes in the para-H2 (f(sub p)) distribution are subtle, with a 0.02-0.03 rise over the spring hemisphere (200-500 mbar) perturbed by (i) low-f(sub p) air advected by both the springtime storm of 2010 and equatorial upwelling; and (ii) subsidence of high-f(sub p) air at northern high latitudes, responsible for a developing north-south asymmetry in f(sub p). Conversely, the shifting asymmetry in the para-H2 disequilibrium primarily reflects the changing temperature structure (and hence the equilibrium distribution of f(sub p)), rather than actual changes in f(sub p) induced by chemical conversion or transport. CIRS results interpolated to the same point in the seasonal cycle as re-analysed Voyager-1 observations (early northern spring) show qualitative consistency from year to year (i.e., the same tropospheric asymmetries in temperature and f(sub p)), with the exception of the tropical tropopause near the equatorial zones and belts, where downward propagation of a cool temperature anomaly associated with Saturn's stratospheric oscillation could potentially perturb tropopause temperatures, para-H2 and winds. Quantitative differences between the Cassini and Voyager epochs suggest that the oscillation is not in phase with the seasonal cycle at these tropospheric depths (i.e., it should be described as quasi-periodic rather than 'semi annual'). Variability in the zonal wind field derived from latitudinal thermal gradients is small (less than 10 m/s per scale height near the tropopause) and mostly affects the broad retrograde jets, with the notable exception of large variability on the northern flank of the equatorial jet. The meridional potential vorticity (PV) gradient, and hence the 'staircase of PV' associated with spatial variations in the vigour of vertical mixing, has varied over the course of the mission but maintained its overall shape. PV gradients in latitude and altitude are used to estimate the atmospheric refractive index for the propagation of stationary planetary (Rossby) waves, predicting that such wave activity would be confined to regions of real refractivity (tropical regions plus bands at 35-45 in both hemispheres). The penetration depth of these regions into the upper troposphere is temporally variable (potentially associated with stratification changes), whereas the latitudinal structure is largely unchanged over time (associated with the zonal jet system).

The Relationship Between the Zonal Mean ITCZ and Regional Precipitation during the mid-Holocene

NASA Astrophysics Data System (ADS)

Niezgoda, K.; Noone, D.; Konecky, B.

2017-12-01

Characteristics of the zonal mean Tropical Rain Belt (TRB, i.e. the ITCZ + the land-based monsoons) are often inferred from individual proxy records of precipitation or other hydroclimatic variables. However, these inferences can be misleading. Here, an isotope-enabled climate model simulation is used to evaluate metrics of the zonal mean ITCZ vs. regional hydrological characteristics during the mid-Holocene (MH, 6 kya). The MH provides a unique perspective on the relationship between the ITCZ and regional hydrology because of large, orbitally-driven shifts in tropical precipitation as well as a critical mass of proxy records. By using a climate model with simulated water isotopes, characteristics of atmospheric circulation and water transport processes can be inferred, and comparison with isotope proxies can be made more directly. We find that estimations of the zonal-mean ITCZ are insufficient for evaluating regional responses of hydrological cycles to forcing changes. For example, one approximation of a 1.5-degree northward shift in the zonal-mean ITCZ position during the MH corresponded well with northward shifts in maximum rainfall in tropical Africa, but did not match southward shifts in the tropical Pacific or longitudinal shifts in the Indian monsoon region. In many regions, the spatial distribution of water vapor isotopes suggests that changes in moisture source and atmospheric circulation were a greater influence on precipitation distribution, intensity, and isotope ratio than the average northward shift in ITCZ latitude. These findings reinforce the idea that using tropical hydrological proxy records to infer zonal-mean characteristics of the ITCZ may be misleading. Rather, tropical proxy records of precipitation, particularly those that record precipitation isotopes, serve as a guideline for regional hydrological changes while model simulations can put them in the context of zonal mean tropical convergence.

Detecting Global Hydrological Cycle Intensification in Sea Surface Salinity

NASA Astrophysics Data System (ADS)

Poague, J.; Stine, A.

2016-12-01

Global warming is expected to intensify the global hydrological cycle, but significant regional differences exist in the predicted response. The proposed zonal mean thermodynamic response is enhanced horizontal moisture transport associated with increased saturation vapor pressure, which in turn drives additional net precipitation in the tropics and at high latitudes and additional net evaporation in the subtropics. Sea surface salinity (SSS) anomalies are forced from above by changes in evaporation minus precipitation (E-P) and thus will respond to changes in the global hydrological cycle, opening the possibility of using historical SSS anomalies to diagnose the response of the hydrological cycle to warming. We estimate zonal mean SSS trends in the Atlantic and Pacific ocean basins from 1955-2015 to test whether historical changes in the global hydrological cycle are consistent with a primarily thermodynamic response. Motivated by this observation, we calculate the sensitivity of basin zonal-mean SSS anomalies to sea surface temperature (SST) forcing as a function of timescale to diagnose and estimate the signal-to-noise ratio of the purely thermodynamic signal as a function of timescale. High-frequency variability in SSS anomalies is likely to be influenced by variability in atmospheric circulation, complicating the attribution of the link between basin zonal-mean SSS anomalies and global SST anomalies. We therefore estimate the basin zonal mean SSS anomaly response to the major modes of large-scale dynamic variability. We find a strong correlation between detrended zonal-mean SSS anomalies and the Pacific-North American index (R=0.71,P<0.01) in the Pacific Ocean. We interpret the relationship between zonal mean SSS anomalies and temperature in terms of the relative contribution of thermodynamic and dynamic processes.

The Detection of Diffuse Extended Structure in 3C 273: Implications for Jet Power

NASA Astrophysics Data System (ADS)

Punsly, Brian; Kharb, Preeti

2016-12-01

We present deep Very Large Array imaging of 3C 273 in order to determine the diffuse, large scale radio structure of this famous radio-loud quasar. Diffuse extended structure (radio lobes) is detected for the first time in these observations as a consequence of high dynamic range in the 327.5 and 1365 MHz images. This emission is used to estimate a time averaged jet power, 7.2 × 1043 erg s-1 < \\overline{Q} < 3.7 × 1044 erg s-1. Brightness temperature arguments indicate consistent values of the time variability Doppler factor and the compactness Doppler factor for the inner jet, δ ≳ 10. Thus, the large apparent broadband bolometric luminosity of the jet, ˜3 × 1046 erg s-1, corresponds to a modest intrinsic luminosity ≳1042 erg s-1, or ˜1% of \\overline{Q}. In summary, we find that 3C 273 is actually a “typical” radio-loud quasar contrary to suggestions in the literature. The modest \\overline{Q} is near the peak of the luminosity distribution for radio-loud quasars and it is consistent with the current rate of dissipation emitted from millimeter wavelengths to gamma rays. The extreme core-jet morphology is an illusion from a near pole-on line of sight to a highly relativistic jet that produces a Doppler enhanced glow that previously swamped the lobe emission. 3C 273 apparently has the intrinsic kpc scale morphology of a classical double radio source, but it is distorted by an extreme Doppler aberration.

A Convective Vorticity Vector Associated With Tropical Convection: A 2D Cloud-Resolving Modeling Study

NASA Technical Reports Server (NTRS)

Gao, Shou-Ting; Ping, Fan; Li, Xiao-Fan; Tao, Wei-Kuo

2004-01-01

Although dry/moist potential vorticity is a useful physical quantity for meteorological analysis, it cannot be applied to the analysis of 2D simulations. A convective vorticity vector (CVV) is introduced in this study to analyze 2D cloud-resolving simulation data associated with 2D tropical convection. The cloud model is forced by the vertical velocity, zonal wind, horizontal advection, and sea surface temperature obtained from the TOGA COARE, and is integrated for a selected 10-day period. The CVV has zonal and vertical components in the 2D x-z frame. Analysis of zonally-averaged and mass-integrated quantities shows that the correlation coefficient between the vertical component of the CVV and the sum of the cloud hydrometeor mixing ratios is 0.81, whereas the correlation coefficient between the zonal component and the sum of the mixing ratios is only 0.18. This indicates that the vertical component of the CVV is closely associated with tropical convection. The tendency equation for the vertical component of the CVV is derived and the zonally-averaged and mass-integrated tendency budgets are analyzed. The tendency of the vertical component of the CVV is determined by the interaction between the vorticity and the zonal gradient of cloud heating. The results demonstrate that the vertical component of the CVV is a cloud-linked parameter and can be used to study tropical convection.

Amplification of warming due to intensification of zonal circulation in the mid-latitudes

NASA Astrophysics Data System (ADS)

Alekseev, Genrikh; Ivanov, Nikolai; Kharlanenkova, Natalia; Kuzmina, Svetlana

2015-04-01

We propose a new index to evaluate the impact of atmospheric zonal transport oscillations on inter-annual variability and trends of average air temperature in mid-latitudes, Northern Hemisphere and globe. A simple model of mid-latitude channel "ocean-land-atmosphere" was used to produce the analytic relationship between the zonal circulation and the land-ocean temperature contrast which was used as a basis for index. An inverse relationship was found between indexes and average mid-latitude, hemisphere and global temperatures during the cold half of year and opposite one in summer. These relationships keep under 400 mb height. In winter relationship describes up to 70, 50 and 40 % of surface air temperature inter-annual variability of these averages, respectively. The contribution of zonal circulation to the increase in the average surface air temperature during warming period 1969-2008 reaches 75% in the mid-latitudes and 40% in the Northern Hemisphere. Proposed mid-latitude index correlates negatively with surface air temperature in the Arctic except summer. ECHAM4 projections with the A1B scenario show that increase of zonal circulation defines more than 74% of the warming in the Northern Hemisphere for 2001-2100. Our analysis confirms that the proposed index is an effective indicator of the climate change caused by variations of the zonal circulation that arise due to anthropogenic and/or natural global forcing mechanisms.

Eastern Tropical Pacific Precipitation Response to Zonal SPCZ events

NASA Astrophysics Data System (ADS)

Durán-Quesada, A. M.; Lintner, B. R.

2014-12-01

Extreme El Niño events and warming conditions in the eastern tropical Pacific have been linked to pronounced spatial displacements of the South Pacific Convergence Zone known as "zonal SPCZ" events.. Using a global dataset of Lagrangian back trajectories computed with the FLEXPART model for the period 1980-2013, comprehensive analysis of the 3D circulation characteristics associated with the SPCZ is undertaken. Ten days history of along-trajectory specific humidity, potential vorticity and temperature are reconstructed for zonal SPCZ events as well as other states,, with differences related to El Niño intensity and development stage as well as the state of the Western Hemisphere Warm Pool. How zonal events influence precipitation over the Eastern Tropical Pacific is examined using back trajectories, reanalysis, TRMM precipitation, and additional satellite derived cloud information. It is found that SPCZ displacements are associated with enhanced convection over the Eastern Tropical Pacific in good agreement with prior work. The connection between intensification of precipitation over the eastern Tropical Pacific during zonal events and suppression of rainfall over the Maritime continent is also described.

A model of the saturation of coupled electron and ion scale gyrokinetic turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Staebler, Gary M.; Howard, Nathan T.; Candy, Jeffrey M.

A new paradigm of zonal flow mixing as the mechanism by which zonal E × B fluctuations impact the saturation of gyrokinetic turbulence has recently been deduced from the nonlinear 2D spectrum of electric potential fluctuations in gyrokinetic simulations. These state of the art simulations span the physical scales of both ion and electron turbulence. It was found that the zonal flow mixing rate, rather than zonal flow shearing rate, competes with linear growth at both electron and ion scales. A model for saturation of the turbulence by the zonal flow mixing was developed and applied to the quasilinear trappedmore » gyro-Landau fluid transport model (TGLF). The first validation tests of the new saturation model are reported in this paper with data from L-mode and high-β p regime discharges from the DIII-D tokamak. Lastly, the shortfall in the predicted L-mode edge electron energy transport is improved with the new saturation model for these discharges but additional multiscale simulations are required in order to verify the safety factor and collisionality dependencies found in the modeling.« less

A model of the saturation of coupled electron and ion scale gyrokinetic turbulence

DOE PAGES

Staebler, Gary M.; Howard, Nathan T.; Candy, Jeffrey M.; ...

2017-05-09

A new paradigm of zonal flow mixing as the mechanism by which zonal E × B fluctuations impact the saturation of gyrokinetic turbulence has recently been deduced from the nonlinear 2D spectrum of electric potential fluctuations in gyrokinetic simulations. These state of the art simulations span the physical scales of both ion and electron turbulence. It was found that the zonal flow mixing rate, rather than zonal flow shearing rate, competes with linear growth at both electron and ion scales. A model for saturation of the turbulence by the zonal flow mixing was developed and applied to the quasilinear trappedmore » gyro-Landau fluid transport model (TGLF). The first validation tests of the new saturation model are reported in this paper with data from L-mode and high-β p regime discharges from the DIII-D tokamak. Lastly, the shortfall in the predicted L-mode edge electron energy transport is improved with the new saturation model for these discharges but additional multiscale simulations are required in order to verify the safety factor and collisionality dependencies found in the modeling.« less