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Articles 31 - 60 of 994

Full-Text Articles in Physical Sciences and Mathematics

One-Parameter Darboux-Deformed Fibonacci Numbers, Stefani C. Mancas, H. C. Rosu Dec 2022

One-Parameter Darboux-Deformed Fibonacci Numbers, Stefani C. Mancas, H. C. Rosu

Publications

One-parameter Darboux deformations are effected for the simple ODE satisfied by the continuous generalizations of the Fibonacci sequence recently discussed by Faraoni and Atieh [Symmetry 13, 200 (2021)], who promoted a formal analogy with the Friedmann equation in the FLRW homogeneous cosmology. The method allows the introduction of deformations of the continuous Fibonacci sequences, hence of Darboux-deformed Fibonacci (non integer) numbers. Considering the same ODE as a parametric oscillator equation, the Ermakov-Lewis invariants for these sequences are also discussed.

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On A Guiding Of Whistler-Mode Waves By Density Gradients, Anatoly V. Streltsov Dec 2022

On A Guiding Of Whistler-Mode Waves By Density Gradients, Anatoly V. Streltsov

Publications

Observations from satellites demonstrate that in the magnetosphere, VLF whistler-mode waves are frequently detected in the narrow transition regions, where the plasma density changes its magnitude over a short distance across the ambient magnetic field. These observations suggest that the small-scale, isolated density gradients can guide the VLF whistler-mode waves along the field. We investigate the guiding of the whistler-mode waves by the transverse density gradients with a size much less than the characteristic perpendicular size of the wave. We found analytical solutions describing these waves in the plasma with a sharp density discontinuity between two homogeneous regions, and confirm …

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Coupling Evidence From Lower Atmosphere To Mesosphere And Ionosphere Through Quasi 27-Day Oscillation, Alan Z. Liu, Kaiming Huang, Hao Cheng, Shaodong Zhang, Chunming Huang, Yun Gong, Gang Chen Nov 2022

Coupling Evidence From Lower Atmosphere To Mesosphere And Ionosphere Through Quasi 27-Day Oscillation, Alan Z. Liu, Kaiming Huang, Hao Cheng, Shaodong Zhang, Chunming Huang, Yun Gong, Gang Chen

Publications

Using meteor radar, radiosonde and digisonde observations and MERRA-2 reanalysis data from 12 August to 31 October 2006, we report a dynamical coupling from the tropical lower atmosphere to the mesosphere and ionospheric F2 region through a quasi 27-day intraseasonal oscillation (ISO). It is interesting that the quasi 27-day ISO is active in the troposphere and stratopause and mesopause regions, exhibiting a three-layer structure. In the mesosphere and lower thermosphere (MLT), the amplitude in the zonal wind increases from about 4 ms at 90 km to 15 ms at 100 km, which is different from previous observations that ISOs generally …

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The Dynamics Of Tsunamigenic Acoustic-Gravity Waves And Bathymetry Effect, Pavel Alexandrovich Inchin, Christopher James Heale, Jonathan Brian Snively, Matthew David Zettergren Nov 2022

The Dynamics Of Tsunamigenic Acoustic-Gravity Waves And Bathymetry Effect, Pavel Alexandrovich Inchin, Christopher James Heale, Jonathan Brian Snively, Matthew David Zettergren

Publications

The investigation of atmospheric tsunamigenic acoustic and gravity wave (TAGW) dynamics, from the ocean surface to the thermosphere, is performed through the numerical computations of the 3D compressible nonlinear Navier-Stokes equations. Tsunami propagation is first simulated using a nonlinear shallow water model, which incorporates instantaneous or temporal evolutions of initial tsunami distributions (ITD). Surface dynamics are then imposed as a boundary condition to excite TAGWs into the atmosphere from the ground level. We perform a case study of a large tsunami associated with the 2011 M9.1 Tohuku-Oki earthquake, and parametric studies with simplified and demonstrative bathymetry and ITD. Our results …

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Climatology Of High-Frequency Gravity Waves Observed By An Airglow Imager At Andes Lidar Observatory, Alan Z. Liu, Bing Cao Nov 2022

Climatology Of High-Frequency Gravity Waves Observed By An Airglow Imager At Andes Lidar Observatory, Alan Z. Liu, Bing Cao

Publications

The long-term climatology of high-frequency quasi-monochromatic gravity waves is presented using multi-year airglow images observed at Andes Lidar Observatory (ALO, 30.3ºS, 70.7ºW) in northern Chile. A large number of high-frequency gravity waves were retrieved from OH airglow images. The distribution of primary wave parameters including horizontal wavelength, vertical wavelength, intrinsic wave speed, and intrinsic wave period are obtained and are in the ranges of 20–30 km, 15–25 km, 50–100 ms-1, and 5–10 min, respectively. The waves tend to propagate against the local background winds and show clear seasonal variations. In austral winter (Ma–Aug), the observed wave occurrence frequency is higher …

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Characteristics Of Kelvin-Helmholtz Waves As Observed By The Mms From September 2015 To June 2017, Katariina Nykyri, Xuanye Ma, Rachel C. Rice Nov 2022

Characteristics Of Kelvin-Helmholtz Waves As Observed By The Mms From September 2015 To June 2017, Katariina Nykyri, Xuanye Ma, Rachel C. Rice

Publications

The Magnetospheric Multiscale (MMS) mission has presented a new opportunity to study the fine scale structures and phenomena of Earth’s magnetosphere, including cross scale processes associated with the Kelvin-Helmholtz Instability (KHI). We present an overview of 19 MMS observations of the KHI from September 2015 to June 2017. Unitless growth rates and unstable solid angles for each of the 19 events were calculated using 5 techniques to automatically detect plasma regions on either side of the magnetopause boundary. There was no apparent correlation between solar wind conditions during the KHI and its growth rate and unstable solid angle, though we …

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Response Of Planetary Waves And Tides To The 2019 Southern Hemisphere Ssw And Q2dw Enhancement In Jan-Feb 2020 Observed By Condor Meteor Radar In Chile And Adelaide Meteor Radar In Australia, Alan Liu, Zishun Qiao, Iain Reid, Javier Fuentes, Chris Adami Nov 2022

Response Of Planetary Waves And Tides To The 2019 Southern Hemisphere Ssw And Q2dw Enhancement In Jan-Feb 2020 Observed By Condor Meteor Radar In Chile And Adelaide Meteor Radar In Australia, Alan Liu, Zishun Qiao, Iain Reid, Javier Fuentes, Chris Adami

Publications

A new multi-static meteor radar (CONDOR) has recently been installed in northern Chile. This CONDOR meteor radar (30.3°S, 70.7°W) and the Adelaide meteor radar (35°S, 138°E) have provided longitudinally spaced observations of the mean winds, tides and planetary waves of the PW-tides interaction cases we present here. We have observed a Quasi-6-Day Wave (Q6DW) enhancement in MLT winds at the middle latitudes (30.3°S, 35°S) during the unusual minor South Hemisphere SSW 2019 by the ground-based meteor radars. Tidal analysis also indicates modulation of the Q6DW w/ amplitude ~15 [m/s] and diurnal tides w/ amplitude ~60 [m/s]. Another case we present …

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Hydrodynamics, Andrei Ludu Nov 2022

Hydrodynamics, Andrei Ludu

Publications

The mathematical description of the states of a fluid is based on the study of three fields defined on the domain occupied by the fluid: the velocity field V, the density ρ, and the pressure field P. These three “unknowns” are determined by integrating other five scalar equations, namely the mass conservation (continuity equation), the three components of the equation of momentum balance (Euler or Navier–Stokes), and the energy balance. This last equation needs in addition information about the thermodynamics of the fluid, so it may need to be supplied with some equation of state. In addition to these five …

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Kinematics Of Fluids, Andrei Ludu Nov 2022

Kinematics Of Fluids, Andrei Ludu

Publications

The goal of this chapter is to discuss the general frame of hydrodynamics, like particle trajectories (path lines), streamlines, streak lines, free surfaces, and fluid surfaces, and to compare their behavior in the Eulerian and Lagrangian frames. The following sections and chapters proceed on the assumption that the fluid is practically continuous and homogeneous in structure. Of course, the concept of continuum is an abstraction that does not take into account the molecular and nuclear structure of matter. In that, we assume that the properties of the fluid do not change if we consider smaller and smaller amounts of matter …

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Meteor Radar Vertical Wind Observation Biases And Mathematical Debiasing Strategies Including The 3dvar+Div Algorithm, Alan Z. Liu, Zishun Qiao, Gunter Stober, Alexander Kozlovsky, Ales Kuchar, Christoph Jacobi, Chris Meek, Diego Janches, Guiping Liu, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Nicholas Mitchell Oct 2022

Meteor Radar Vertical Wind Observation Biases And Mathematical Debiasing Strategies Including The 3dvar+Div Algorithm, Alan Z. Liu, Zishun Qiao, Gunter Stober, Alexander Kozlovsky, Ales Kuchar, Christoph Jacobi, Chris Meek, Diego Janches, Guiping Liu, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Nicholas Mitchell

Publications

Meteor radars have become widely used instruments to study atmospheric dynamics, particularly in the 70 to 110 km altitude region. These systems have been proven to provide reliable and continuous measurements of horizontal winds in the mesosphere and lower thermosphere. Recently, there have been many attempts to utilize specular and/or transverse scatter meteor measurements to estimate vertical winds and vertical wind variability. In this study we investigate potential biases in vertical wind estimation that are intrinsic to the meteor radar observation geometry and scattering mechanism, and we introduce a mathematical debiasing process to mitigate them. This process makes use of …

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How Education On Climate Change Affects Consumers' Willingness To Participate In Carbon Offsetting Programs?, Leila Halawi, Deanna Demattio Sep 2022

How Education On Climate Change Affects Consumers' Willingness To Participate In Carbon Offsetting Programs?, Leila Halawi, Deanna Demattio

Publications

If airlines could have a better understanding of how to induce sustainable behavior in their customers, they can use these methods when building sustainable initiatives such as voluntary carbon offsetting programs. The purpose of the study was to determine if education on the consequences of climate change affects how consumers behave related to their interaction with carbon offsetting programs. Regional Scenarios were introduced with a natural disaster comparable to the region under review. A multistage sampling technique was utilized in this study. Firstly, using a cluster sample, groups were used rather than individual units of the target population. The results …

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Ionospheric Feedback And Ulf Quarter-Waves, Anatoly Streltsov, Evgeny V. Mishin Sep 2022

Ionospheric Feedback And Ulf Quarter-Waves, Anatoly Streltsov, Evgeny V. Mishin

Publications

This paper presents results from the numerical investigation of nonlinear feedback interactions between ULF field-aligned currents (FACs) and the ionospheric plasma in the global magnetospheric resonator with a non-symmetrical distribution of the plasma density in the conjugate hemispheres. The density asymmetry is enhanced by the introduction of the ionospheric valley in the hemisphere where the plasma density is already lower. The main result from this study is that in the non-symmetrical resonator, the ionospheric feedback mechanism, driven by the electric field with the maximum amplitude of 50 mV/m, develops nonlinear, intense, small-scale upward currents with a characteristic quarter-wavelength structure along …

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Rocket Measurements Of Electron Energy Spectra From Earth’S Photoelectron Production Layer, Glyn A. Collinson, Alex Glocer, Dennis Chornay, Robert Mitchell, Rob Pfaff, Tim Cameron, Et. Al. Aug 2022

Rocket Measurements Of Electron Energy Spectra From Earth’S Photoelectron Production Layer, Glyn A. Collinson, Alex Glocer, Dennis Chornay, Robert Mitchell, Rob Pfaff, Tim Cameron, Et. Al.

Publications

Photoelectrons are crucial to atmospheric physics. They heat the atmosphere, strengthen 28 planetary ambipolar electric fields, and enhance the outflow of ions to space. However, 29 there exist only a handful of measurements of their energy spectrum near the peak of 30 photoproduction. We present calibrated energy spectra of pristine photoelectrons at their 31 source by a prototype Dual Electrostatic Analyzer (DESA) instrument flown on July 11 32 2021 aboard the Dynamo-2 sounding rocket (NASA № 36.357). Photopeaks arising from 33 30.4nm He-II spectral line were observed throughout the flight above 120km. DESA also 34 successfully resolved the rarely observed …

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Validated Question Bank For Assessing Pilot Knowledge Of Aviation Weather Appendix: Weather Product Interpretation Questions, Robert Thomas, Cassandra Dommingo, John Kleber, Jackie Mcsorely, Amber Cole, Thomas Guinn, Elizabeth Blickensderfer Aug 2022

Validated Question Bank For Assessing Pilot Knowledge Of Aviation Weather Appendix: Weather Product Interpretation Questions, Robert Thomas, Cassandra Dommingo, John Kleber, Jackie Mcsorely, Amber Cole, Thomas Guinn, Elizabeth Blickensderfer

General Aviation Weather Display Interpretation

This appendix supplements the Thomas et al. (2022) paper titled “Validated Question Bank for Assessing Pilot Knowledge of Aviation Weather ” which validates a set of weather product interpretation questions that can be used to measure a pilot’s understanding of weather. The assessment consists of 15 weather product interpretation topics which can be administered as a single 65-question survey or, as in the Thomas et al. (2022) study, two assessments of 33 and 32 questions each separated by topic. The set of 65 questions can be found in this appendix along with a table which demonstrates how to separate the …

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Revisit Of Open Clusters Upk 39, Upk 41 And Phoc 39 : A New Binary Open Cluster Found, Xianhao Ye, Terry D. Oswalt, Jingkun Zhao, Yong Yang, Gang Zhao Jul 2022

Revisit Of Open Clusters Upk 39, Upk 41 And Phoc 39 : A New Binary Open Cluster Found, Xianhao Ye, Terry D. Oswalt, Jingkun Zhao, Yong Yang, Gang Zhao

Publications

We investigate the three open clusters near Aquila Rift cloud, named as UPK 39 (c1 hereafter), UPK 41 (c2 hereafter) in Sim et al. (2019) and PHOC 39 (c3 hereafter) in Hunt & Reffert (2021), respectively. Using photometric passpands, reddening, and extinction from Gaia DR3, we construct the color-absolute-magnitude diagram (CAMD). Using isochrone fits their ages are estimated as 6.3 ± 0.9, 8.1 ± 1.4 and 21.8 ± 2.2 Myr, respectively. Their proper motions and radial velocities, estimated using data from Gaia and LAMOST are very similar. From their orbits, relative distances among them at different times, kinematics, ages, and …

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Climatology Of Deep O+ Dropouts In The Night-Time F-Region In Solar Minimum Measured By A Langmuir Probe Onboard The International Space Station, Shantanab Debchoudhury, Aroh Barjatya, Joseh I. Minow, Victoria N. Coffey, Linda N. Parker Jul 2022

Climatology Of Deep O+ Dropouts In The Night-Time F-Region In Solar Minimum Measured By A Langmuir Probe Onboard The International Space Station, Shantanab Debchoudhury, Aroh Barjatya, Joseh I. Minow, Victoria N. Coffey, Linda N. Parker

Publications

The Floating Potential Measurement Unit (FPMU) onboard the International Space Station includes a Wide sweeping Langmuir Probe (WLP) that has been operating in the F-region of the ionosphere at ∼400 km since 2006. While traditional Langmuir probe estimates include critical plasma parameters like electron density and temperature, we have also extracted the O+ percentage from the total ion constituents. This O+ composition dataset from the recent minimum in the Solar Cycle 24 reveals orbits with dropouts in O+ to below 80% of the total background ion density at ISS orbital altitudes. The observed O+ percentages during these dropouts are much …

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Modeling Studies Of Gravity Wave Dynamics In Highly Structured Environments: Reflection, Trapping, Instability, Momentum Transport, Secondary Gravity Waves, And Induced Flow Responses, Wenjun Dong, David C. Fritts, Michael P. Hickey, Alan Z. Liu, Thomas S. Lund, Shaodong Zhang, Yanying Yan, Fan Yang Jun 2022

Modeling Studies Of Gravity Wave Dynamics In Highly Structured Environments: Reflection, Trapping, Instability, Momentum Transport, Secondary Gravity Waves, And Induced Flow Responses, Wenjun Dong, David C. Fritts, Michael P. Hickey, Alan Z. Liu, Thomas S. Lund, Shaodong Zhang, Yanying Yan, Fan Yang

Publications

A compressible numerical model is applied for three-dimensional (3-D) gravity wave (GW) packets undergoing momentum deposition, self-acceleration (SA), breaking, and secondary GW (SGW) generation in the presence of highly-structured environments enabling thermal and/or Doppler ducts, such as a mesospheric inversion layer (MIL), tidal wind (TW), or combination of MIL and TW. Simulations reveal that ducts can strongly modulate GW dynamics. Responses modeled here include reflection, trapping, suppressed transmission, strong local instabilities, reduced SGW generations, higher altitude SGW responses, and induced large-scale flows. Instabilities that arise in ducts experience strong dissipation after they emerge, while trapped smaller-amplitude and smaller-scale GWs can …

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Statistical Characteristics Of High-Frequency Gravity Waves Observed By An Airglow Imager At Andes Lidar Observatory, Alan Z. Liu, Bing Cao May 2022

Statistical Characteristics Of High-Frequency Gravity Waves Observed By An Airglow Imager At Andes Lidar Observatory, Alan Z. Liu, Bing Cao

Publications

The long-term statistical characteristics of high-frequency quasi-monochromatic gravity waves are presented using multi-year airglow images observed at Andes Lidar Observatory (ALO, 30.3° S, 70.7° W) in northern Chile. The distribution of primary gravity wave parameters including horizontal wavelength, vertical wavelength, intrinsic wave speed, and intrinsic wave period are obtained and are in the ranges of 20–30 km, 15–25 km, 50–100 m s−1, and 5–10 min, respectively. The duration of persistent gravity wave events captured by the imager approximately follows an exponential distribution with an average duration of 7–9 min. The waves tend to propagate against the local background winds and …

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Mesosphere And Lower Thermosphere Changes Associated With The 2 July 2019 Total Eclipse In South America Over The Andes Lidar Observatory, Cerro Pachon, Chile, A. Liu, F. Vargas, G. Swenson, C. Segura, P. Vega, J. Fuentes, D. Pautet, M. Taylor, Y. Zhao, Y. Morton, H. Bourne May 2022

Mesosphere And Lower Thermosphere Changes Associated With The 2 July 2019 Total Eclipse In South America Over The Andes Lidar Observatory, Cerro Pachon, Chile, A. Liu, F. Vargas, G. Swenson, C. Segura, P. Vega, J. Fuentes, D. Pautet, M. Taylor, Y. Zhao, Y. Morton, H. Bourne

Publications

This article presents the results of a week of observations around the 2 July 2019, total Chilean eclipse. The eclipse occurred between 19:22 and 21:46 UTC, with complete sun disc obscuration at 20:38–20:40 UTC (16:38–16:40 LT) over the Andes Lidar Observatory (ALO) at (30.3°S, 70.7°W). Observations were carried out using ALO instrumentation with the goal to observe possible eclipse-induced effects on the mesosphere and lower thermosphere region (MLT; 75–105 km altitude). To complement our data set, we have also utilized TIMED/SABER temperatures and ionosonde electron density measurements taken at the University of La Serena's Juan Soldado Observatory. Observed events include …

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A Monte Carlo Method For Evaluating Empirical Gyrochronology Models And Its Application To Wide Binary Benchmarks, Tomomi Otani, Ted Von Hippel, Derek Buzasi, Terry Oswalt, Alexander Stone-Martinez, Patrice Majewski May 2022

A Monte Carlo Method For Evaluating Empirical Gyrochronology Models And Its Application To Wide Binary Benchmarks, Tomomi Otani, Ted Von Hippel, Derek Buzasi, Terry Oswalt, Alexander Stone-Martinez, Patrice Majewski

Publications

No abstract provided.

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The Replacement Rule For Nonlinear Shallow Water Waves, A. Ludu, Z. Zong Apr 2022

The Replacement Rule For Nonlinear Shallow Water Waves, A. Ludu, Z. Zong

Publications

When a (1 + 1)-dimensional nonlinear PDE in real function η(x, t) admits localized traveling solutions we can consider L to be the average width of the envelope, A the average value of the amplitude of the envelope, and V the group velocity of such a solution. The replacement rule (RR or nonlinear dispersion relation) procedure is able to provide a simple qualitative relation between these three parameters, without actually solve the equation. Examples are provided from KdV, C-H and BBM equations, but the procedure appears to be almost universally valid for such (1 + 1)-dimensional nonlinear PDE and their …

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Improving White Dwarfs As Chronometers With Gaia Parallaxes And Spectroscopic Metallicities, Adam Moss, Ted Von Hippel, Elliot Robinson, Kareem El-Badry, David C. Stenning, David Van Dyk, Morgan Fouesneau, Coryn A.L. Bailer-Jones, Elizabeth Jeffery, Jimmy Sargent, Isabelle Kloc, Natalie Moticska Apr 2022

Improving White Dwarfs As Chronometers With Gaia Parallaxes And Spectroscopic Metallicities, Adam Moss, Ted Von Hippel, Elliot Robinson, Kareem El-Badry, David C. Stenning, David Van Dyk, Morgan Fouesneau, Coryn A.L. Bailer-Jones, Elizabeth Jeffery, Jimmy Sargent, Isabelle Kloc, Natalie Moticska

Publications

White dwarfs (WDs) offer unrealized potential in solving two problems in astrophysics: stellar age accuracy and precision. WD cooling ages can be inferred from surface temperatures and radii, which can be constrained with precision by high-quality photometry and parallaxes. Accurate and precise Gaia parallaxes along with photometric surveys provide information to derive cooling and total ages for vast numbers of WDs. Here we analyze 1372 WDs found in wide binaries with main-sequence (MS) companions and report on the cooling and total age precision attainable in these WD+MS systems. The total age of a WD can be further constrained if its …

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Oxygen Ion Escape At Venus Associated With Three-Dimensional Kelvin-Helmholtz Instability, Tong Dang, Xuanye Ma, Jiuhou Le, Binzheng Zhang, Tielong Zhang, Zhonghua Yao, John Lyon, Sudong Xiao, Maodong Yan, Oliver Brambles, Kareem Sorathia Mar 2022

Oxygen Ion Escape At Venus Associated With Three-Dimensional Kelvin-Helmholtz Instability, Tong Dang, Xuanye Ma, Jiuhou Le, Binzheng Zhang, Tielong Zhang, Zhonghua Yao, John Lyon, Sudong Xiao, Maodong Yan, Oliver Brambles, Kareem Sorathia

Publications

How oxygens escape from Venus has long been a fundamental but controversial topic in the planetary research. Among various key mechanisms, the Kelvin-Helmholtz instability (KHI) has been suggested to play an important role in the oxygen ion escape from Venus. Limited by either scarce in-situ observations or simplified theoretical estimations, the mystery of oxygen ion escape process associated with KHI is still unsettled. Here we present the first three-dimensional configuration of KHI at Venus with a global multifluid magnetohydrodynamics model, showing a significantly fine structure and evolution of the KHI. KHI mainly occurred at the low latitude boundary layer if …

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Simulation Of Infrasonic Acoustic Wave Imprints On Airglow Layers During The 2016 M7.8 Kaikoura Earthquake, P. A. Inchin, J. Aguilar Guerrero, J. B. Snively, Y. Kaneko Mar 2022

Simulation Of Infrasonic Acoustic Wave Imprints On Airglow Layers During The 2016 M7.8 Kaikoura Earthquake, P. A. Inchin, J. Aguilar Guerrero, J. B. Snively, Y. Kaneko

Publications

Simulations of hypothesized but unobserved mesopause airglow (MA) disturbances generated by infrasonic acoustic waves (IAWs) during the 2016 M7.8 Kaikoura earthquake are performed. Realistic surface displacements are calculated in a forward seismic wave propagation model and incorporated into a 3-D nonlinear compressible neutral atmosphere model as a source of IAWs at the surface-air interface. Inchin et al. (2021), https://doi.org/10.1029/2020av000260 previously showed that Global Positioning System-based total electron content (TEC) observations can be used to constrain the finite-fault kinematics of the Kaikoura earthquake. However, due to limitations of Global Navigation Satellite System network coverage and coalescence of nonlinear IAW fronts, they …

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3d Numerical Simulation Of Secondary Wave Generation From Mountain Wave Breaking Over Europe, Christopher J. Heale, Katrina Bossert, Sharon L. Vadas Feb 2022

3d Numerical Simulation Of Secondary Wave Generation From Mountain Wave Breaking Over Europe, Christopher J. Heale, Katrina Bossert, Sharon L. Vadas

Publications

In this paper, we simulate an observed mountain wave event over central Europe and investigate the subsequent generation, propagation, phase speeds and spatial scales, and momentum deposition of secondary waves under three different tidal wind conditions. We find the mountain wave breaks just below the lowest critical level in the mesosphere. As the mountain wave breaks, it extends outwards along the phases and fluid associated with the breaking flows downstream of its original location by 500–1,000 km. The breaking generates a broad range of secondary waves with horizontal scales ranging from the mountain wave instability scales (20–300 km), to multiples …

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Feedback Interactions Between The Ionosphere And Magnetosphere At Middle Latitude, Mergen Alimaganbetov, Anatoly Streltsov Feb 2022

Feedback Interactions Between The Ionosphere And Magnetosphere At Middle Latitude, Mergen Alimaganbetov, Anatoly Streltsov

Publications

Observations show that magnetic pulsations with frequencies around 1 mHz are frequently detected simultaneously at different latitudes on the ground, in the inner magnetosphere, and in the solar wind. The coupling between oscillations in the dynamic pressure or magnetic field carried by the solar wind and the ULF waves detected on the ground at high latitudes has been suggested in several studies. We present results from a numerical study of ultra-low-frequency waves detected by the ground magnetometers at middle latitudes during substorm. We investigate the hypothesis that these waves are generated by the ionospheric feedback instability driven by the large-scale …

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Venus Mountain Waves In The Upper Atmosphere Simulated By A Time-Invariant Linear Full-Wave Spectral Model, Michael P. Hickey, Richard L. Walterscheid, Thomas Navarro, Gerald Schubert Feb 2022

Venus Mountain Waves In The Upper Atmosphere Simulated By A Time-Invariant Linear Full-Wave Spectral Model, Michael P. Hickey, Richard L. Walterscheid, Thomas Navarro, Gerald Schubert

Publications

A 2-D spectral full-wave model is described that simulates the generation and propagation of mountain waves over idealized topography in Venus' atmosphere. Modeled temperature perturbations are compared with the Akatsuki observations. Lower atmosphere eddy diffusivity and stability play a major role in the upward propagation of gravity waves from their mountain sources. Two local times (LT) are considered. For LT = 11 h the waves are blocked by a critical level near 100 km altitude, while for LT = 16 h the waves propagate into the thermosphere. As a result of the small scale height in the Venus thermosphere, for …

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Comparison Of Mlt Momentum Fluxes Over The Andes At Four Different Latitudinal Sectors Using Multistatic Radar Configurations, J. Federico Conte, Alan Liu, Zishun Qiao, Jorge L. Chau, David C. Fritts, José L. Hormaechea, Jacobo O. Salvador, Marco A. Milla Feb 2022

Comparison Of Mlt Momentum Fluxes Over The Andes At Four Different Latitudinal Sectors Using Multistatic Radar Configurations, J. Federico Conte, Alan Liu, Zishun Qiao, Jorge L. Chau, David C. Fritts, José L. Hormaechea, Jacobo O. Salvador, Marco A. Milla

Publications

The middle atmosphere over South America, particularly above the Andes mountain range, is known as one of the most dynamically active regions in the world. Previous studies have investigated wave dynamics at mesosphere and lower thermosphere (MLT) altitudes within this region, but only a handful of them have made use of continuous measurements provided by specular meteor radars (SMRs). Furthermore, it was only until recently that MLT horizontal wind gradients were estimated for the first time using Spread Spectrum Interferometric Multistatic meteor radar Observing Network (SIMONe) Argentina, a multistatic SMR network located in southern Patagonia. By observing larger amounts of …

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The Data Analytics And The Science Revolution, Leila Halawi, Amal Clarke, Kelly George Feb 2022

The Data Analytics And The Science Revolution, Leila Halawi, Amal Clarke, Kelly George

Publications

This text highlights the difference between analytics and data science, using predictive analytic techniques to analyze different historical data, including aviation data and concrete data, interpreting the predictive models, and highlighting the steps to deploy the models and the steps ahead. The book combines the conceptual perspective and a hands-on approach to predictive analytics using SAS VIYA, an analytic and data management platform. The authors use SAS VIYA to focus on analytics to solve problems, highlight how analytics is applied in the airline and business environment, and compare several different modeling techniques. They decipher complex algorithms to demonstrate how they …

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Resonant Alfvén Waves In The Lower Auroral Ionosphere: Evidence For The Nonlinear Evolution Of The Ionospheric Feedback Instability, Hassanali Akbari, Anatoly Streltsov, Robert Pfaff, James Clemmons, Henry Freudenreich, Douglas Rowland Jan 2022

Resonant Alfvén Waves In The Lower Auroral Ionosphere: Evidence For The Nonlinear Evolution Of The Ionospheric Feedback Instability, Hassanali Akbari, Anatoly Streltsov, Robert Pfaff, James Clemmons, Henry Freudenreich, Douglas Rowland

Publications

During the “Auroral Jets” experiment from Poker Flat, Alaska on 2 March 2017, two NASA sounding rockets were simultaneously launched into the active auroral ionosphere. The rockets were equipped with instrumentation to measure DC and AC electric fields, magnetic fields, energetic electrons, plasma density, and neutral winds and achieved apogees of 190 and 330 km. A prominent feature of the electric and magnetic field observations is the presence of localized large-amplitude (±40 mV/m and ±100 nT) small-scale (λ⊥∼ 1 km) Alfvén wave structures at altitudes as low as 150 km in the vicinity of up- and down-ward current regions. We …

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