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Utah State University

2015

All Physics Faculty Publications

Articles 1 - 16 of 16

Full-Text Articles in Physical Sciences and Mathematics

Comparison Of Coincident Rayleigh-Scatter And Sodium Resonance Lidar Temperature Measurements From The Mesosphere-Lower-Thermosphere Region, Leda Sox, Vincent B. Wickwar, Neal R. Criddle, Tao Yuan Dec 2015

Comparison Of Coincident Rayleigh-Scatter And Sodium Resonance Lidar Temperature Measurements From The Mesosphere-Lower-Thermosphere Region, Leda Sox, Vincent B. Wickwar, Neal R. Criddle, Tao Yuan

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There are relatively few instruments that have the capabilities to make near continuous measurements of the mesosphere-lower-thermosphere (MLT) region. Rayleigh scatter and resonance lidars, particularly sodium resonance lidar, have been the two dominant ground-based techniques for acquiring mesosphere and MLT vertical temperature profiles, respectively, for more than two decades. With these measurements, the dynamics (gravity waves, tides) and long-term temperature trends (upper atmosphere cooling) of the MLT region can be studied. The Utah State University (USU; 41.7º N, 111.8º W) campus hosts a unique upper atmospheric observatory which houses both a high-power, large-aperture Rayleigh lidar and a sodium resonance Doppler …

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Estimation Of Cold Plasma Outflow During Geomagnetic Storms, S. Haaland, A. Eriksson, M. Andre, L. Maes, L. Baddeley, A. Barakat, R. Chappell, V. Eccles, C. Johnsen, B. Lybekk, K. Li, A. Pedersen, Robert W. Schunk, D. Welling Dec 2015

Estimation Of Cold Plasma Outflow During Geomagnetic Storms, S. Haaland, A. Eriksson, M. Andre, L. Maes, L. Baddeley, A. Barakat, R. Chappell, V. Eccles, C. Johnsen, B. Lybekk, K. Li, A. Pedersen, Robert W. Schunk, D. Welling

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Low-energy ions of ionospheric origin constitute a significant contributor to the magnetospheric plasma population. Measuring cold ions is difficult though. Observations have to be done at sufficiently high altitudes and typically in regions of space where spacecraft attain a positive charge due to solar illumination. Cold ions are therefore shielded from the satellite particle detectors. Furthermore, spacecraft can only cover key regions of ion outflow during segments of their orbit, so additional complications arise if continuous longtime observations, such as during a geomagnetic storm, are needed. In this paper we suggest a new approach, based on a combination of synoptic …

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Daytime Plasma Drifts In The Equatorial Lower Ionosphere, D. Hui, B. G. Fejer Nov 2015

Daytime Plasma Drifts In The Equatorial Lower Ionosphere, D. Hui, B. G. Fejer

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We have used extensive radar measurements from the Jicamarca Observatory during low solar flux periods to study the quiet time variability and altitudinal dependence of equatorial daytime vertical and zonal plasma drifts. The daytime vertical drifts are upward and have largest values during September-October. The day-to-day variability of these drifts does not change with height between 150 and 600 km, but the bimonthly variability is much larger in the F region than below about 200 km. These drifts vary linearly with height generally increasing in the morning and decreasing in the afternoon. The zonal drifts are westward during the day …

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A Coordinated Study Of 1 H Mesoscale Gravity Waves Propagating From Logan To Boulder With Crrl Na Doppler Lidars And Temperature Mapper, Xian Lu, Cao Chen, Wentao Huang, John A. Smith, Xinzhao Chu, Tao Yuan, Pierre-Dominique Pautet, Michael J. Taylor, Jie Gong, Chihoko Y. Cullens Oct 2015

A Coordinated Study Of 1 H Mesoscale Gravity Waves Propagating From Logan To Boulder With Crrl Na Doppler Lidars And Temperature Mapper, Xian Lu, Cao Chen, Wentao Huang, John A. Smith, Xinzhao Chu, Tao Yuan, Pierre-Dominique Pautet, Michael J. Taylor, Jie Gong, Chihoko Y. Cullens

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We present the first coordinated study using two lidars at two separate locations to characterize a 1 h mesoscale gravity wave event in the mesopause region. The simultaneous observations were made with the Student Training and Atmospheric Research (STAR) Na Doppler lidar at Boulder, CO, and the Utah State University Na Doppler lidar and temperature mapper at Logan, UT, on 27 November 2013. The high precision possessed by the STAR lidar enabled these waves to be detected in vertical wind. The mean wave amplitudes are ~0.44 m/s in vertical wind and ~1% in relative temperature at altitudes of 82–107 km. …

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Momentum Flux Estimates Accompanying Multiscale Gravity Waves Over Mount Cook, New Zealand, On 13 July 2014 During The Deepwave Campaign, K. Bossert, D. C. Fritts, B. P. Williams, Michael J. Taylor, B. Kaifler, A. Dornbrack, I. M. Reid, D. J. Murphy, A. J. Spargo, A. D. Mackinnon, Pierre-Dominique Pautet Sep 2015

Momentum Flux Estimates Accompanying Multiscale Gravity Waves Over Mount Cook, New Zealand, On 13 July 2014 During The Deepwave Campaign, K. Bossert, D. C. Fritts, B. P. Williams, Michael J. Taylor, B. Kaifler, A. Dornbrack, I. M. Reid, D. J. Murphy, A. J. Spargo, A. D. Mackinnon, Pierre-Dominique Pautet

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Observations performed with a Rayleigh lidar and an Advanced Mesosphere Temperature Mapper aboard the National Science Foundation/National Center for Atmospheric Research Gulfstream V research aircraft on 13 July 2014 during the Deep Propagating Gravity Wave Experiment (DEEPWAVE) measurement program revealed a large-amplitude, multiscale gravity wave (GW) environment extending from ~20 to 90 km on flight tracks over Mount Cook, New Zealand. Data from four successive flight tracks are employed here to assess the characteristics and variability of the larger- and smaller-scale GWs, including their spatial scales, amplitudes, phase speeds, and momentum fluxes. On each flight, a large-scale mountain wave (MW) …

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Magnetic Meridional Winds In The Thermosphere Obtained From Global Assimilation Of Ionospheric Measurements (Gaim) Model, Levan Lomidze, Ludger Scherliess, Robert W. Schunk Sep 2015

Magnetic Meridional Winds In The Thermosphere Obtained From Global Assimilation Of Ionospheric Measurements (Gaim) Model, Levan Lomidze, Ludger Scherliess, Robert W. Schunk

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Thermospheric neutral winds play an important part in the dynamics of ionospheric plasma and represent one of the key inputs for ionospheric physics-based models. Yet wind measurements are scarce and generally lack global coverage and continuity. To help mitigate this shortcoming, a data assimilation model was used to estimate neutral winds in the low- and middle-latitude thermosphere. Seasonal global maps of NmF2 andhmF2 were generated from Constellation Observing System for Meteorology, Ionosphere, and Climate radio occultation measurements for geomagnetically quiet and low solar flux conditions. The maps were assimilated into the Utah State University Global Assimilation of …

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Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos Jul 2015

Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos

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Rainich-type conditions giving a spacetime “geometrization” of matter fields in general relativity are reviewed and extended. Three types of matter are considered: perfect fluids, scalar fields, and elec- tromagnetic fields. Necessary and sufficient conditions on a spacetime metric for it to be part of a perfect fluid solution of the Einstein equa- tions are given. Formulas for constructing the fluid from the metric are obtained. All fluid results hold for any spacetime dimension. Ge- ometric conditions on a metric which are necessary and sufficient for it to define a solution of the Einstein-scalar field equations and for- mulas for constructing …

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Global Features Of The Disturbance Winds During Storm Time Deduced From Champ Observations, C. Xiong, H. Luhr, B. G. Fejer Jun 2015

Global Features Of The Disturbance Winds During Storm Time Deduced From Champ Observations, C. Xiong, H. Luhr, B. G. Fejer

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A wind-driven disturbance dynamo has been postulated many decades ago. But due to the sparseness of thermospheric wind measurements, details of the phenomena could not be investigated. In this study we use the CHAMP zonal wind observations from 2001 to 2005 to investigate the global features of the disturbance winds during magnetically disturbed periods. The disturbance zonal wind is mainly westward, which increases with magnetic activity and latitude. At subauroral region, the westward zonal wind is strongly enhanced in the magnetic local time (MLT) sector from afternoon to midnight, which we relate to the plasma drift within the subauroral polarization …

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Mechanisms Underlying The Prereversal Enhancement Of The Vertical Plasma Drift In The Low-Latitude Ionosphere, J. V. Eccles, J. P. St. Maurice, Robert W. Schunk Jun 2015

Mechanisms Underlying The Prereversal Enhancement Of The Vertical Plasma Drift In The Low-Latitude Ionosphere, J. V. Eccles, J. P. St. Maurice, Robert W. Schunk

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The evening prereversal enhancement (PRE) of the vertical plasma drift has important consequences for the Appleton density anomaly and the stability of the nighttime ionosphere. Simplified simulations were used to review the three competing theories of the PRE origin, to explore their relative importance, and to indentify their interdependence. The mechanisms involved in the generation and climatology of the PRE are, first, a curl-free electric field response to rapid changes in the vertical electric field associated with the nighttime F region dynamo; second, a divergence of Hall currents in the E region away from the magnetic equator; and, third, the …

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Long-Term Midlatitude Mesopause Region Temperature Trend Deduced From Quarter Century (1990-2014) Na Lidar Observations, Chiao Y. She, D. A. Krueger, Tao Yuan Mar 2015

Long-Term Midlatitude Mesopause Region Temperature Trend Deduced From Quarter Century (1990-2014) Na Lidar Observations, Chiao Y. She, D. A. Krueger, Tao Yuan

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The long-term midlatitude temperature trend between 85 and 105 km is deduced from 25 years (March 1990-December 2014) of Na Lidar observations. With a strong warming episode in the 1990s, the time series was least-square fitted to an 11-parameter nonlinear function. This yields a cooling trend starting from an insignificant value of 0.64 ± 0.99 K decade-1 at 85 km, increasing to a maximum of 2.8 ± 0.58K decade-1 between 91 and 93 km, and then decreasing to a warming trend above 103 km. The geographic altitude dependence of the trend is in general agreement with model predictions. …

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Low-Latitude Scintillation Weakening During Sudden Stratospheric Warming Events, E. R. De Paula, O. F. Jonah, A. O. Moraes, E. A. Kherani, B. G. Fejer, M. A. Abdu, M.T. A.H. Muella, I. S. Batista, S. L.G. Dutra, R. R. Paes Mar 2015

Low-Latitude Scintillation Weakening During Sudden Stratospheric Warming Events, E. R. De Paula, O. F. Jonah, A. O. Moraes, E. A. Kherani, B. G. Fejer, M. A. Abdu, M.T. A.H. Muella, I. S. Batista, S. L.G. Dutra, R. R. Paes

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Global Positioning System (GPS) L1-frequency (1.575 GHz) amplitude scintillations at São José dos Campos (23.1°S, 45.8°W, dip latitude 17.3°S), located under the southern crest of the equatorial ionization anomaly, are analyzed during the Northern Hemisphere winter sudden stratospheric warming (SSW) events of 2001/2002, 2002/2003, and 2012/2013. The events occurred during a period when moderate to strong scintillations are normally observed in the Brazilian longitude sector. The selected SSW events were of moderate and major categories and under low Kp conditions. The most important result of the current study is the long-lasting (many weeks) weakening of scintillation amplitudes at this low-latitude …

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Simultaneous Observations Of The Phase-Locked 2 Day Wave At Adelaide, Cerro Pachon, And Darwin, R. L. Walterscheid, J. H. Hecht, L. J. Gelinas, A. Mackinnon, R. A. Vincent, I. M. Reid, S. J. Franke, Yucheng Zhao, Michael J. Taylor, Pierre-Dominique Pautet Mar 2015

Simultaneous Observations Of The Phase-Locked 2 Day Wave At Adelaide, Cerro Pachon, And Darwin, R. L. Walterscheid, J. H. Hecht, L. J. Gelinas, A. Mackinnon, R. A. Vincent, I. M. Reid, S. J. Franke, Yucheng Zhao, Michael J. Taylor, Pierre-Dominique Pautet

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The Southern Hemisphere summer 2 day wave (TDW) is the most dramatic large-scale event of the upper mesosphere. The winds accelerate over _1 week, may attain > 70 m/s, and are often accompanied by a near disappearance of the diurnal tide and stabilization of the period close to 48 h. We denote this as the phase-locked 2 day wave (PL/TDW). We have examined airglow and meteor radar (MR) wind data from the Andes Lidar Observatory (Cerro Pachon, Chile:30¡S, 289.3¡E), MR data from Darwin (12.5¡S, 131¡E) and airglow and medium frequency radar data from the University of Adelaide (34.7¡S, 138.6¡E) for the …

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Synthesis And Characterization Of Polymer (Sulfonated Poly-Ether-Ether-Ketone) Based Nanocomposite (H-Boron Nitride) Membrane For Hydrogen Storage, R. Muthu Nareth, S. Rajashabla, Ramaiyan Navaneetha Kannan Jan 2015

Synthesis And Characterization Of Polymer (Sulfonated Poly-Ether-Ether-Ketone) Based Nanocomposite (H-Boron Nitride) Membrane For Hydrogen Storage, R. Muthu Nareth, S. Rajashabla, Ramaiyan Navaneetha Kannan

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The development of light weight and compact hydrogen storage materials is still prerequisite to fuel-cell technology to be fully competitive. The present experimental study reports the hydrogen storage capability of sulfonated poly-ether-ether-ketone (SPEEK)-hexagonal boron nitride (h-BN) (SPEEK-h-BN) nanocomposite membranes. The nanocomposite membranes are prepared by considering various amount of h-BN (0, 1, 3 and 5 wt. %) by phase inversion technique. The degree of sulfonation of the PEEK (SPEEK) is found to be 65% by Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy. Hydrogen adsorption studies have been carried out using a Seiverts-like hydrogenation setup. The membranes are characterized …

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Variation Of The Linear Biconformal Action, James Thomas Wheeler Jan 2015

Variation Of The Linear Biconformal Action, James Thomas Wheeler

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We find the field equations of biconformal space in a basis adapted to Lagrangian submanifolds on which the restriction of the Killing metric is non-degenerate.

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Studies In Torsion Free Biconformal Spaces. Case 2: \Gamma_{-} = 0, James Thomas Wheeler Jan 2015

Studies In Torsion Free Biconformal Spaces. Case 2: \Gamma_{-} = 0, James Thomas Wheeler

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We show that the solutions for the symmetric part of the connection in homogeneous biconformal space also satisfy the more general field equations of curved biconformal spaces in the case when \gamma_{-} = 0.

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Studies In Torsion Free Biconformal Spaces, James Thomas Wheeler Jan 2015

Studies In Torsion Free Biconformal Spaces, James Thomas Wheeler

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We study whether the solutions for the symmetric part of the connection in homogeneous biconformal space also satisfy the more general field equation of curved biconformal spaces. We show that the six field equations for the torsion and co-torsion are satisfied by vanishing torsion together with the Lorentzian form of the metric when γ+ = 0.

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