Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
-
- Ionosphere (3)
- Equatorial (2)
- Equatorial disturbance dynamo (2)
- Extended Supersymmetry (2)
- Long term (2)
-
- Mesosphere (2)
- Radar (2)
- Sodium lidar (2)
- Spread F (2)
- Supergravity Models (2)
- Thermosphere (2)
- 28 duration (1)
- 6300 airglow (1)
- AdS-CFT Correspondence (1)
- Biconformal (1)
- Biotechnology (1)
- Classical black holes (1)
- Cosmology & Astrophysics (1)
- C‐type structure (1)
- Diamagnetic currents (1)
- Disturbed ionosphere (1)
- Disturbed thermosphere (1)
- Drifts (1)
- Electric fields (1)
- Electron (1)
- Emission (1)
- Emission yield (1)
- Energy deposition (1)
- Equatorial plasma depletions (1)
- Flux (1)
Articles 1 - 21 of 21
Full-Text Articles in Physics
Model‐Based Properties Of The Dayside Open/Closed Boundary: Is There A Ut‐Dependent Variation?, David A. Smith, Jan Josef Sojka
Model‐Based Properties Of The Dayside Open/Closed Boundary: Is There A Ut‐Dependent Variation?, David A. Smith, Jan Josef Sojka
All Physics Faculty Publications
The open‐closed boundary (OCB) defines a region of significant transformation in Earth's protective magnetic shield. Principle among these changes is the transition of magnetic field lines from having two foot points, one in each hemisphere, to one foot point at Earth, the other mapping to the solar wind. Charged particles in the solar wind are able to follow these open field lines into Earth's upper atmosphere. The OCB also defines the polar cap boundary. Being able to identify and track the OCB allows study of several components of the geomagnetic system. Among them are the electrodynamics of the geomagnetic field …
Halving Iso(7) Supergravity, Adolfo Guarino, Javier Tarrío, Oscar J. Varela
Halving Iso(7) Supergravity, Adolfo Guarino, Javier Tarrío, Oscar J. Varela
All Physics Faculty Publications
Half-maximal, N = 4, sectors of D = 4 N = 8 supergravity with a dyonic ISO(7) gauging are investigated. We focus on a half-maximal sector including three vector multiplets, that arises as a certain SO(3)R-invariant sector of the full theory. We discuss the embedding of this sector into the largest half-maximal sector of the N = 8 supergravity retaining six vector multiplets. We also provide its canonical N = 4 formulation and show that, from this perspective, our model leads in its own right to a new explicit gauging of N = 4 supergravity. Finally, expressions for …
Melissa: System Description And Spectral Features Of Pre- And Post-Midnight F-Region Echoes, Fabiano S. Rodrigues, Weijia Zhan, Marco A. Milla, B. G. Fejer, Eurico R. De Paula, Acacio C. Neto, Angela M. Santos, Inez S. Batista
Melissa: System Description And Spectral Features Of Pre- And Post-Midnight F-Region Echoes, Fabiano S. Rodrigues, Weijia Zhan, Marco A. Milla, B. G. Fejer, Eurico R. De Paula, Acacio C. Neto, Angela M. Santos, Inez S. Batista
All Physics Faculty Publications
Most of the low‐latitude ionospheric radar observations in South America come from the Jicamarca Radio Observatory, located in the western longitude sector (∼75°W). The deployment of the 30 MHz FAPESP‐Clemson‐INPE (FCI) coherent backscatter radar in the magnetic equatorial site of São Luis, Brazil, in 2001 allowed observations to be made in the eastern sector (∼45°W). However, despite being operational for several years (2001–2012), FCI only made observations during daytime and pre‐midnight hours, with a few exceptions. Here, we describe an upgraded system that replaced the FCI radar and present results of full‐night F‐region observations. This radar is referred to …
Embedding The Su(3) Sector Of So(8) Supergravity In D = 11, Gabriel Larios, Praxitelis Ntokos, Oscar J. Varela
Embedding The Su(3) Sector Of So(8) Supergravity In D = 11, Gabriel Larios, Praxitelis Ntokos, Oscar J. Varela
All Physics Faculty Publications
The SU(3)-invariant sector of maximal supergravity in four dimensions with an SO(8) gauging is uplifted to D = 11 supergravity. In order to do this, the SU(3)-neutral sector of the tensor and duality hierarchies of the D = 4 �� = 8 supergravity is first worked out. The consistent D = 11 embedding of the full, dynamical SU(3) sector is then expressed at the level of the D = 11 metric and three-form gauge field in terms of these D = 4 tensors. The redundancies introduced by this approach are eliminated at the level of the D = 11 four-form …
Minimal D = 4 �� = 2 Supergravity From D = 11: An M-Theory Free Lunch, Gabriel Larios, Oscar J. Varela
Minimal D = 4 �� = 2 Supergravity From D = 11: An M-Theory Free Lunch, Gabriel Larios, Oscar J. Varela
All Physics Faculty Publications
We present a new consistent truncation of D = 11 supergravity to D = 4 �� = 2 minimal gauged supergravity, on the seven-dimensional internal Riemannian space corresponding to the most general class of D = 11 solutions with an AdS4 factor and �� = 2 supersymmetry. A truncation ansatz is proposed and its consistency checked at the level of the D = 11 Bianchi identity, bosonic equations of motion, and supersymmetry variations of the gravitino. The general class includes an �� = 2 AdS4 solution dual to the conformal, low energy physics phase corresponding to a mass …
Dynamic Secondary Electron Emission In Rough Composite Materials, Leandro Olano, Maria E. Dávila, John R. Dennison, Petronilo Martín-Iglesias, Isabel Montero
Dynamic Secondary Electron Emission In Rough Composite Materials, Leandro Olano, Maria E. Dávila, John R. Dennison, Petronilo Martín-Iglesias, Isabel Montero
All Physics Faculty Publications
The interaction of ionizing radiation with matter is of critical importance in numerous areas of science and technology like space and vacuum technology and even medicine and biotechnology. Secondary electron emission is a consequence of electron irradiation on materials. We achieve extremely low secondary electron emission yield values smaller than 0.2, even up to incident electron energies ~1 keV, due to an undocumented synergy between neighbouring metal and dielectric domains in composite samples. To investigate this experimental discovery, we propose a simple 3D model where the dielectric and metallic domains are arranged in parallel and interleaved. The proposed surface profile …
Generalized Near Horizon Extreme Binary Black Hole Geometry, Jacob Ciafre, Shahar Hadar, Erin Rickenbach, Maria J. Rodriguez
Generalized Near Horizon Extreme Binary Black Hole Geometry, Jacob Ciafre, Shahar Hadar, Erin Rickenbach, Maria J. Rodriguez
All Physics Faculty Publications
We present a new vacuum solution of Einstein’s equations describing the near horizon region of two neutral, extreme (zero-temperature), corotating, nonidentical Kerr black holes. The metric is stationary, asymptotically near horizon extremal Kerr (NHEK), and contains a localized massless strut along the symmetry axis between the black holes. In the deep infrared, it flows to two separate throats which we call “pierced-NHEK” geometries: each throat is NHEK pierced by a conical singularity. We find that in spite of the presence of the strut for the pierced-NHEK geometries the isometry group SL(2,R)×U(1) is restored. We find the physical parameters and entropy.
Solar Response And Long‐Term Trend Of Midlatitude Mesopause Region Temperature Based On 28 Years (1990–2017) Of Na Lidar Observations, Chiao-Yao She, Uwe Berger, Zhao-Ai Yan, Tao Yuan, F.-J. Lübken, David A. Krueger, Xiong Hu
Solar Response And Long‐Term Trend Of Midlatitude Mesopause Region Temperature Based On 28 Years (1990–2017) Of Na Lidar Observations, Chiao-Yao She, Uwe Berger, Zhao-Ai Yan, Tao Yuan, F.-J. Lübken, David A. Krueger, Xiong Hu
All Physics Faculty Publications
We present midlatitude solar response and linear trend from Colorado State University/Utah State University Na lidar nocturnal temperature observations between 1990 and 2017. Along with the nightly mean temperatures (_Ngt), we also use the corresponding 2‐hr means centered at midnight (_2MN), resulting in vertical trend profiles similar in shapes as those previously published. The 28‐year trend from _Ngt (_2MN) data set starts from a small warming at 85 km, to cooling at 87 (88) km, reaching a maximum of 1.85 ± 0.53 (1.09 ± 0.74) at 92 (93) km and turns positive again at 102 (100) km. The 6‐month winter …
On The Balance Between Plasma And Magnetic Pressure Across Equatorial Plasma Depletions, J. Rodríguez-Zuluaga, C. Stolle, Y. Yamazaki, H. Lühr, J. Park, Ludger Scherliess, J. L. Chau
On The Balance Between Plasma And Magnetic Pressure Across Equatorial Plasma Depletions, J. Rodríguez-Zuluaga, C. Stolle, Y. Yamazaki, H. Lühr, J. Park, Ludger Scherliess, J. L. Chau
All Physics Faculty Publications
In magnetized plasmas such as the ionosphere, electric currents develop in regions of strong density gradients to balance the resulting plasma pressure gradients. These currents, usually known as diamagnetic currents decrease the magnetic pressure where the plasma pressure increases, and vice versa. In the low‐latitude ionosphere, equatorial plasma depletions (EPDs) are well known for their steep plasma density gradients and adverse effect on radio wave propagation. In this paper, we use continuous measurements of the magnetic field and electron density from the European Space Agency's Swarm constellation mission to assess the balance between plasma and magnetic pressure across large‐scale EPDs. …
Equatorial Disturbance Dynamo Vertical Plasma Drifts Over Jicamarca: Bi‐Monthly And Solar Cycle Dependence, Luis A. Navarro Dominguez, B. G. Fejer, Ludger Scherliess
Equatorial Disturbance Dynamo Vertical Plasma Drifts Over Jicamarca: Bi‐Monthly And Solar Cycle Dependence, Luis A. Navarro Dominguez, B. G. Fejer, Ludger Scherliess
All Physics Faculty Publications
We use extensive incoherent scatter radar observations from the Jicamarca Radio Observatory to study the local time and bi‐monthly dependence of the equatorial disturbance dynamo vertical plasma drifts on solar flux and geomagnetic activity. We show that the daytime disturbance drifts have generally small magnitudes with largest values before noon and an apparent annual variation. Near dusk, they are downward throughout the year with largest values during the equinoxes and smallest during June solstice. These downward drifts increase strongly with solar flux, and shift to later local times. They also increase with increasing geomagnetically active conditions with no apparent local …
The Long‐Term Trends Of Nocturnal Mesopause Temperature And Altitude Revealed By Na Lidar Observations Between 1990 And 2018 At Midlatitude, Tao Yuan, Stanley C. Solomon, Chiao -Y. She, D. A. Krueger, Han-Li Liu
The Long‐Term Trends Of Nocturnal Mesopause Temperature And Altitude Revealed By Na Lidar Observations Between 1990 And 2018 At Midlatitude, Tao Yuan, Stanley C. Solomon, Chiao -Y. She, D. A. Krueger, Han-Li Liu
All Physics Faculty Publications
The mesopause, a boundary between mesosphere and thermosphere with the coldest atmospheric temperature, is formed mainly by the combining effects of radiative cooling of CO2, and the vertical adiabatic flow in the upper atmosphere. A continuous multidecade (1990‐2018) nocturnal temperature data base of an advanced Na lidar, obtained at Fort Collins, CO (41°N, 105°W), and at Logan, UT (42°N, 112°W), provides an unprecedented opportunity to study the long‐term variations of this important atmospheric boundary. In this study, we categorize the lidar‐observed mesopause into two categories: the “high mesopause” (HM) above 97 km during nonsummer months, mainly formed through the radiative …
Pmc Turbo: Studying Gravity Wave And Instability Dynamics In The Summer Mesosphere Using Polar Mesospheric Cloud Imaging And Profiling From A Stratospheric Balloon, David C. Fritts, Amber D. Miller, C. Bjorn Kjellstrand, Christopher Geach, Bifford P. Williams, Bernd Kaifler, Natalie Kaifler, Glenn Jones, Markus Rapp, Michele Limon, Jason Reimuller, Ling Wang, Shaul Hanany, Sonja Gisinger, Yucheng Zhao, Gunter Stober, Cora E. Randall
Pmc Turbo: Studying Gravity Wave And Instability Dynamics In The Summer Mesosphere Using Polar Mesospheric Cloud Imaging And Profiling From A Stratospheric Balloon, David C. Fritts, Amber D. Miller, C. Bjorn Kjellstrand, Christopher Geach, Bifford P. Williams, Bernd Kaifler, Natalie Kaifler, Glenn Jones, Markus Rapp, Michele Limon, Jason Reimuller, Ling Wang, Shaul Hanany, Sonja Gisinger, Yucheng Zhao, Gunter Stober, Cora E. Randall
All Physics Faculty Publications
The Polar Mesospheric Cloud Turbulence (PMC Turbo) experiment was designed to observe and quantify the dynamics of small‐scale gravity waves (GWs) and instabilities leading to turbulence in the upper mesosphere during polar summer using instruments aboard a stratospheric balloon. The PMC Turbo scientific payload comprised seven high‐resolution cameras and a Rayleigh lidar. Overlapping wide and narrow camera field of views from the balloon altitude of ~38 km enabled resolution of features extending from ~20 m to ~100 km at the PMC layer altitude of ~82 km. The Rayleigh lidar provided profiles of temperature below the PMC altitudes and of the …
First Ground‐Based Conjugate Observations Of Stable Auroral Red (Sar) Arcs, C. Martinis, J. Baumgardner, M. Mendillo, Michael J. Taylor, T. Moffat-Griffin, J. Wroten, C. Sullivan, R. Macinnis, B. Alford, Y. Nishimura
First Ground‐Based Conjugate Observations Of Stable Auroral Red (Sar) Arcs, C. Martinis, J. Baumgardner, M. Mendillo, Michael J. Taylor, T. Moffat-Griffin, J. Wroten, C. Sullivan, R. Macinnis, B. Alford, Y. Nishimura
All Physics Faculty Publications
During the geomagnetic storm of 1 June 2013, all‐sky imagers located at geomagnetically conjugate locations at Millstone Hill, USA (42.6°N, 71.4°W, 50.9° mag lat) and at Rothera, Antarctica (67.5°S, 68.1°W, ‐53.2° mag lat), allowed us to measure a stable auroral red (SAR) arc simultaneously in both hemispheres for the first time. The arc measured in one hemisphere was observed very close to its conjugate location in the opposite hemisphere. While spatial characteristics, such as equatorward motion and latitudinal extent, were similar at both sites, morphological properties, for example, arc brightness and shape of the poleward edges, differed. The overall brightness …
The International Community Coordinated Modeling Center Space Weather Modeling Capabilities Assessment: Overview Of Ionosphere/Thermosphere Activities, Ludger Scherliess, I. Tsagouri, E. Yizengaw, S. Bruinsma, J. S. Shim, A. Coster, J. M. Retterer
The International Community Coordinated Modeling Center Space Weather Modeling Capabilities Assessment: Overview Of Ionosphere/Thermosphere Activities, Ludger Scherliess, I. Tsagouri, E. Yizengaw, S. Bruinsma, J. S. Shim, A. Coster, J. M. Retterer
All Physics Faculty Publications
The Earth's ionosphere/thermosphere (I/T) system exhibits complicated weather variability that can have adverse effects on human operations and systems, and consequently, there is a need for both accurate and reliable specifications and forecasts for this region. As part of the international effort to evaluate and assess the predictive capabilities of space weather models, four working groups for the I/T system have been created with the goal to devise a concerted model validation effort for the I/T environment. This paper presents an overview of the team efforts and reports on the progress made. As a first step, the working teams have …
General Relativity As A Biconformal Gauge Theory, James Thomas Wheeler
General Relativity As A Biconformal Gauge Theory, James Thomas Wheeler
All Physics Faculty Publications
We consider the conformal group of a space of dim n=p+q, with SO(p,q) metric. The quotient of this group by its homogeneous Weyl subgroup gives a principal fiber bundle with 2n-dim base manifold and Weyl fibers. The Cartan generalization to a curved 2n-dim geometry admits an action functional linear in the curvatures. Because symmetry is maintained between the translations and the special conformal transformations in the construction, these spaces are called biconformal; this same symmetry gives biconformal spaces overlapping structures with double field theories, including manifest T-duality. We establish that biconformal geometry is …
A Modeling Study Of The Responses Of Mesosphere And Lower Thermosphere Winds To Geomagnetic Storms At Middle Latitudes, Jingyuan Li, Wenbin Wang, Jianyong Lu, Jia Yue, Alan G. Burns, Tao Yuan, Xuetao Chen, Wenjun Dong
A Modeling Study Of The Responses Of Mesosphere And Lower Thermosphere Winds To Geomagnetic Storms At Middle Latitudes, Jingyuan Li, Wenbin Wang, Jianyong Lu, Jia Yue, Alan G. Burns, Tao Yuan, Xuetao Chen, Wenjun Dong
All Physics Faculty Publications
Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIMEGCM) simulations are diagnostically analyzed to investigate the causes of mesosphere and lower thermosphere (MLT) wind changes at middle latitudes during the 17 April 2002 storm. In the early phase of the storm, middle‐latitude upper thermospheric wind changes are greater and occur earlier than MLT wind changes. The horizontal wind changes cause downward vertical wind changes, which are transmitted to the MLT region. Adiabatic heating and heat advection associated with downward vertical winds cause MLT temperature increases. The pressure gradient produced by these temperature changes and the Coriolis force then drive strong equatorward …
On The Long Lasting “C‐Type” Structures In The Sodium Lidargram: The Lifetime Of Kelvin‐Helmholtz Billows In The Mesosphere And Lower Thermosphere Region, S. Mondal, S. Sarkhel, Jay Agarwal, D. Chakrabarty, R. Sekar, Tao Yuan, Xuguang Cai, Alan Z. Liu, Satonori Nozawa, Norihito Saito, Takuya D. Kawahara, Martin G. Mlynczak, James M. Russell Iii
On The Long Lasting “C‐Type” Structures In The Sodium Lidargram: The Lifetime Of Kelvin‐Helmholtz Billows In The Mesosphere And Lower Thermosphere Region, S. Mondal, S. Sarkhel, Jay Agarwal, D. Chakrabarty, R. Sekar, Tao Yuan, Xuguang Cai, Alan Z. Liu, Satonori Nozawa, Norihito Saito, Takuya D. Kawahara, Martin G. Mlynczak, James M. Russell Iii
All Physics Faculty Publications
In order to understand the characteristics of long‐lasting “C‐type” structure in the Sodium (Na) lidargram, six cases from different observational locations have been analyzed. The Na lidargram, collected from low‐, middle‐, and high‐latitude sites, show long lifetime of the C‐type structures which is believed to be the manifestation of Kelvin‐Helmholtz (KH) billows in the Mesosphere and Lower Thermosphere (MLT) region. In order to explore the characteristics of the long‐lasting C‐type structures, the altitude profile of square of Brunt‐Väisälä frequency in the MLT region has been derived using the temperature profile collected from the Na lidar instruments and the SABER instrument …
Photochemistry On The Bottom Side Of The Mesospheric Na Layer, Tao Yuan, Wuhu Feng, John M. C. Plane, Daniel R. Marsh
Photochemistry On The Bottom Side Of The Mesospheric Na Layer, Tao Yuan, Wuhu Feng, John M. C. Plane, Daniel R. Marsh
All Physics Faculty Publications
Lidar observations of the mesospheric Na layer have revealed considerable diurnal variations, particularly on the bottom side of the layer, where more than an order-of-magnitude increase in Na density has been observed below 80 km after sunrise. In this paper, multi-year Na lidar observations are utilized over a full diurnal cycle at Utah State University (USU) (41.8o N, 111.8o W) and a global atmospheric model of Na with 0.5 km vertical resolution in the mesosphere and lower thermosphere (WACCM-Na) to explore the dramatic changes of Na density on the bottom side of the layer. Photolysis of the principal reservoir NaHCO3 …
Radar Studies Of Height-Dependent Equatorial F Region Vertical And Zonal Plasma Drifts, S. A. Shidler, F. S. Rodrigues, B. G. Fejer, M. A. Milla
Radar Studies Of Height-Dependent Equatorial F Region Vertical And Zonal Plasma Drifts, S. A. Shidler, F. S. Rodrigues, B. G. Fejer, M. A. Milla
All Physics Faculty Publications
We present the results of an analysis of long-term measurements of ionospheric F region E × B plasma drifts in the American/Peruvian sector. The analysis used observations made between 1986 and 2017 by the incoherent scatter radar of the Jicamarca Radio Observatory. Unlike previous studies, we analyzed both vertical and zonal components of the plasma drifts to derive the geomagnetically quiet time climatological variation of the drifts as a function of height and local time. We determine the average behavior of the height profiles of the drifts for different seasons and distinct solar flux conditions. Our results show good agreement …
Storm-Time Thermospheric Winds Over Peru, Luis A. Navarro Dominguez, B. G. Fejer
Storm-Time Thermospheric Winds Over Peru, Luis A. Navarro Dominguez, B. G. Fejer
All Physics Faculty Publications
We used Fabry-Perot Interferometer (FPI) observations at Jicamarca, Nasca and Arequipa, Peru from 2011 to 2017 to study the nighttime zonal and meridional disturbance winds over the Peruvian equatorial region. We derived initially the seasonal-dependent average thermospheric winds corresponding to 12 hours of continuous geomagnetically quiet conditions. These quiet-time climatological winds, which are in general agreement with results from the Horizontal Wind Model (HWM14), were then used as baselines for the calculation of the disturbance winds. Our results indicate that the nighttime zonal disturbance winds are westward with peak values near midnight and with magnitudes much larger than predicted by …
A Multi-Ion, Flux-Corrected Transport Based Hydrodynamic Model For The Plasmasphere Refilling Problem, Kausik Chatterjee, Robert W. Schunk
A Multi-Ion, Flux-Corrected Transport Based Hydrodynamic Model For The Plasmasphere Refilling Problem, Kausik Chatterjee, Robert W. Schunk
All Physics Faculty Publications
The objective of this paper is the application of a newly-developed Flux-Corrected Transport (FCT) based hydrodynamic solution methodology to the plasmasphere refilling problem following a geomagnetic storm. The FCT method is extremely well-suited to the solution of nonlinear partial differential equations with shocks and discontinuities. In this solution methodology, every ion species is modeled as two separate fluids originating from the northern and southern hemispheres. We present refilling results that includes three ion (H+, He+ and O+) species and two neutrals (H and O). We believe that with additional modifications, the model …