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- Gravity waves (28)
- Waves and tides (21)
- Acoustic-gravity waves (19)
- Airglow and aurora (19)
- Ionosphere (13)
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- Middle atmosphere dynamics (13)
- Gravity wave (9)
- Mesospheric dynamics (8)
- Airglow (7)
- Atmospheric gravity waves (7)
- Acoustic waves (6)
- Middle atmosphere: composition and chemistry (6)
- Kelvin-Helmholtz instability (5)
- Mountain waves (5)
- Thermosphere: energy deposition (5)
- Tsunami (5)
- Turbulence (5)
- Alfvén waves (4)
- Ducting (4)
- Ionospheric feedback instability (4)
- Mesosphere (4)
- Middle atmosphere (4)
- Thermosphere (4)
- Thermosphere: composition and chemistry (4)
- Tsunamis and storm surges (4)
- Atmosphere (3)
- Auroral ionosphere (3)
- Field-aligned currents (3)
- Instability (3)
- Mesopause (3)
Articles 31 - 60 of 185
Full-Text Articles in Physical Sciences and Mathematics
Atmospheric Tomography Using The Nordic Meteor Radar Cluster And Chilean Observation Network De Meteor Radars: Network Details And 3d-Var Retrieval, Gunter Stober, Alan Z. Liu, Zishun Qiao, Alexander Kozlovsky, Masaki Tsutsumi, Chris Hall, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Patrick J. Espy, Robert E. Hibbins, Nicholas Mitchell
Atmospheric Tomography Using The Nordic Meteor Radar Cluster And Chilean Observation Network De Meteor Radars: Network Details And 3d-Var Retrieval, Gunter Stober, Alan Z. Liu, Zishun Qiao, Alexander Kozlovsky, Masaki Tsutsumi, Chris Hall, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Patrick J. Espy, Robert E. Hibbins, Nicholas Mitchell
Publications
Ground-based remote sensing of atmospheric parameters is often limited to single station observations by vertical profiles at a certain geographic location. This is a limiting factor for investigating gravity wave dynamics as the spatial information is often missing, e.g., horizontal wavelength, propagation direction or intrinsic frequency. In this study, we present a new retrieval algorithm for multistatic meteor radar networks to obtain tomographic 3-D wind fields within a pre-defined domain area. The algorithm is part of the Agile Software for Gravity wAve Regional Dynamics (ASGARD) and called 3D-Var, and based on the optimal estimation technique and Bayesian statistics. The performance …
Observations And Validation Of Plasma Density, Temperature, And O+ Abundance From A Langmuir Probe Onboard The International Space Station, Shantanab Debchoudhury, Aroh Barjatya, Joseph I. Minow, Victoria N. Coffey, Michael O. Chandler
Observations And Validation Of Plasma Density, Temperature, And O+ Abundance From A Langmuir Probe Onboard The International Space Station, Shantanab Debchoudhury, Aroh Barjatya, Joseph I. Minow, Victoria N. Coffey, Michael O. Chandler
Publications
The Floating Potential Measurement Unit (FPMU) has been operational on board the International Space Station (ISS) since 2006. One of the instruments in the FPMU suite is a spherical wide-sweeping Langmuir probe, referred to as the WLP, which is sampled at a temporal cadence of 1 s giving in-situ measurements of the plasma density and electron temperature. In this study we present our refinements to the Langmuir probe analysis algorithm that address the uncertainties associated with photoelectron emission current from the metal probe. We also derive the fraction of O+ ions as a secondary data product, which shows decrease …
Venus Mountain Waves In The Upper Atmosphere Simulated By A Time-Invariant Linear Full-Wave Spectral Model, Michael P. Hickey, Thomas Navarro, Gerald Schubert, Richard L. Walterscheid
Venus Mountain Waves In The Upper Atmosphere Simulated By A Time-Invariant Linear Full-Wave Spectral Model, Michael P. Hickey, Thomas Navarro, Gerald Schubert, Richard L. Walterscheid
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 = 11h 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 LT …
Auroral Heating Of Plasma Patches Due To High-Latitude Reconnection, Joaquin Diaz Pena, Joshua Semeter, Yukitoshi Nishimura, Roger Varney, Ashton Reimer, Marc Hairston, Matthew Zettergren, Michael Hirsch, Olga Verkhoglyadova, Keisuke Hosokawa, Kazuo Shiokawa
Auroral Heating Of Plasma Patches Due To High-Latitude Reconnection, Joaquin Diaz Pena, Joshua Semeter, Yukitoshi Nishimura, Roger Varney, Ashton Reimer, Marc Hairston, Matthew Zettergren, Michael Hirsch, Olga Verkhoglyadova, Keisuke Hosokawa, Kazuo Shiokawa
Publications
This study exploits the volumetric sampling capabilities of the Resolute Bay Incoherent Scatter Radar (RISR-N) in collaboration with all-sky imagery and in-situ measurements (DMSP) to examine the interplay between cold plasma transport and auroral precipitation during a high-latitude lobe reconnection event on the dawn side. The IMF had an impulsive negative excursion in B$_z$ embedded within a prolonged period of B$_z>0$ and B$_y
Inferring The Evolution Of A Large Earthquake From Its Acoustic Impacts On The Ionosphere, P. A. Inchin, J. B. Snively, M. D. Zettergren, Y. Kaneko, A. Komjathy
Inferring The Evolution Of A Large Earthquake From Its Acoustic Impacts On The Ionosphere, P. A. Inchin, J. B. Snively, M. D. Zettergren, Y. Kaneko, A. Komjathy
Publications
We investigate the possibility to constrain the evolution of the 2016 M7.8 Kaikoura earthquake evolution based on Global Positioning System signal-derived ionospheric total electron content (TEC) perturbations, that represent plasma responses to infrasonic acoustic waves (IAWs) generated by surface motion. This earthquake exhibited unusual complexity and some first-order aspects of its evolution remain unclear; for example, how and when the Papatea fault (PF) and the corresponding large surface deformation occurred. For various earthquake models, a seismic wave propagation code is used to simulate time-dependent surface deformations, which then excite IAWs in a 3D compressible nonlinear atmospheric model, coupled with a …
Atmospheric Tomography Using The Nordic Meteor Radar Cluster And Chilean Observation Network De Meteor Radars: Network Details And 3dvar Retrieval, Gunter Stober, Alan Liu, Zishun Qiao, Alexander Kozlovsky, Masaki Tsutsumi, Chris Hall, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Patrick J. Espy, Robert E. Hibbins, Nicholas Mitchell
Atmospheric Tomography Using The Nordic Meteor Radar Cluster And Chilean Observation Network De Meteor Radars: Network Details And 3dvar Retrieval, Gunter Stober, Alan Liu, Zishun Qiao, Alexander Kozlovsky, Masaki Tsutsumi, Chris Hall, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Patrick J. Espy, Robert E. Hibbins, Nicholas Mitchell
Publications
Ground-based remote sensing of atmospheric parameters is often limited to single station observations of vertical profiles at a certain geographic location. This can be a limiting factor to investigating gravity wave dynamics. In this study we present a new retrieval algorithm for multi-static meteor radar networks to obtain tomographic 3D wind fields within a pre-defined domain area. The algorithm is part of the Agile Software for Gravity wAve Regional Dynamics (ASGARD) called 5 3DVAR, and based on the optimal estimation technique and Bayesian statistics. The performance of the 3DVAR retrieval is demonstrated using two meteor radar networks, the Nordic Meteor …
Gravity Waves, Na Lidar, Yafang Guo, Alan Z. Liu
Gravity Waves, Na Lidar, Yafang Guo, Alan Z. Liu
Publications
Vertical energy transports due to dissipating gravity waves in the mesopause region (85–100 km) are analyzed using over 400 h of observational data obtained from a narrow-band sodium wind-temperature lidar located at Andes Lidar Observatory (ALO), Cerro Pachón (30.25°S, 70.73°W), Chile. Sensible heat flux is directly estimated using measured temperature and vertical wind; energy flux is estimated from the vertical wavenumber and frequency spectra of temperature perturbations; and enthalpy flux is derived based on its relationship with sensible heat and energy fluxes. Sensible heat flux is mostly downward throughout the region. Enthalpy flux exhibits an annual oscillation with maximum downward …
Kelvin-Helmholtz Billow Interactions And Instabilities In The Mesosphere Over The Andes Lidar Observatory: 1. Observations, J. H. Hecht, R. L. Walterscheid, A. Z. Liu, D. C. Fritts, L. J. Gelinas, R. J. Rudy
Kelvin-Helmholtz Billow Interactions And Instabilities In The Mesosphere Over The Andes Lidar Observatory: 1. Observations, J. H. Hecht, R. L. Walterscheid, A. Z. Liu, D. C. Fritts, L. J. Gelinas, R. J. Rudy
Publications
A very high spatial resolution (∼25 m pixel at 90 km altitude) OH airglow imager was installed at the Andes Lidar Observatory on Cerro Pachón, Chile, in February 2016. This instrument was collocated with a Na wind-temperature lidar. On 1 March 2016, the lidar data showed that the atmosphere was dynamically unstable before 0100 UT and thus conducive to the formation of Kelvin-Helmholtz instabilities (KHIs). The imager revealed the presence of a KHI and an apparent atmospheric gravity wave (AGW) propagating approximately perpendicular to the plane of primary KHI motions. The AGW appears to have induced modulations of the shear …
Large Scale Upper-Level Precursors For Dust Storm Formation Over North Africa And Poleward Transport To The Iberian Peninsula. Part I: An Observational Analysis, J.A. G. Orza, Michael L. Kaplan, S. Dhital, S. Fiedler
Large Scale Upper-Level Precursors For Dust Storm Formation Over North Africa And Poleward Transport To The Iberian Peninsula. Part I: An Observational Analysis, J.A. G. Orza, Michael L. Kaplan, S. Dhital, S. Fiedler
Publications
The analysis of three extreme African dust outbreaks over the Iberian Peninsula (IP) shows that a double Rossby wave breaking (RWB) process in the polar jet (PJ) creates the conditions for dust storm formation over subtropical deserts in North Africa and the restructuring of upper-level air flows critical for the dust transport poleward after ablation. Two consecutive anticyclonic RWBs initiate over the IP and the adjacent Atlantic, the first commencing 10 days before dust reaches the IP and the second three to five days later. The first RWB becomes quasi-stationary over the eastern Mediterranean when the second RWB develops. In …
Observations Of An Extreme Atmospheric River Storm With A Diverse Sensor Network, B. J. Hatchett, Michael L. Kaplan, Q. Cao, P. B. Dawson, C. J. Ellis, Et Al.
Observations Of An Extreme Atmospheric River Storm With A Diverse Sensor Network, B. J. Hatchett, Michael L. Kaplan, Q. Cao, P. B. Dawson, C. J. Ellis, Et Al.
Publications
Observational networks enhance real‐time situational awareness for emergency and water resource management during extreme weather events. We present examples of how a diverse, multitiered observational network in California provided insights into hydrometeorological processes and impacts during a 3‐day atmospheric river storm centered on 14 February 2019. This network, which has been developed over the past two decades, aims to improve understanding and mitigation of effects from extreme storms influencing water resources and natural hazards. We combine atmospheric reanalysis output and additional observations to show how the network allows: (1) the validation of record cool season precipitable water observations over southern …
Evidence For Horizontal Blocking And Reflection Of A Small-Scale Gravity Wave In The Mesosphere, N. R. Criddle, C. Heale, J. Snively, P. -D. Pautet, T. Yuan, Y. Zhao, M. J. Taylor
Evidence For Horizontal Blocking And Reflection Of A Small-Scale Gravity Wave In The Mesosphere, N. R. Criddle, C. Heale, J. Snively, P. -D. Pautet, T. Yuan, Y. Zhao, M. J. Taylor
Publications
The variations of the horizontal phase velocity of an internal gravity wave, generated by wave “blocking” or “reflection” due to an inhomogeneous wind field, have been predicted theoretically and numerically investigated but had yet to be captured experimentally. In this paper, through a collaborative observation campaign using a sodium (Na) Temperature/Wind lidar and a collocated Advanced Mesospheric Temperature Mapper (AMTM) at Utah State University (USU), we report the first potential evidence of such a unique gravity wave process. The study shows that a small-scale wave, captured by the AMTM, with initial observed horizontal phase velocity of 37 ± 5 m/s …
Modeling Of Ionospheric Responses To Atmospheric Acoustic And Gravity Waves Driven By The 2015 Nepal M W 7.8 Gorkha Earthquake, P. A. Inchin, J. B. Snively, M. D. Zettergren, A. Komjathy, O. P. Verkhoglyadova, S. Tulasi Ram
Modeling Of Ionospheric Responses To Atmospheric Acoustic And Gravity Waves Driven By The 2015 Nepal M W 7.8 Gorkha Earthquake, P. A. Inchin, J. B. Snively, M. D. Zettergren, A. Komjathy, O. P. Verkhoglyadova, S. Tulasi Ram
Publications
Near- and far-field ionospheric responses to atmospheric acoustic and gravity waves (AGWs) generated by surface displacements during the 2015 Nepal 7.8 Gorkha earthquake are simulated. Realistic surface displacements driven by the earthquake are calculated in three-dimensional forward seismic waves propagation simulation, based on kinematic slip model. They are used to excite AGWs at ground level in the direct numerical simulation of three-dimensional nonlinear compressible Navier-Stokes equations with neutral atmosphere model, which is coupled with a two-dimensional nonlinear multifluid electrodynamic ionospheric model. The importance of incorporating earthquake rupture kinematics for the simulation of realistic coseismic ionospheric disturbances (CIDs) is demonstrated and …
An Analysis Of The Atmospheric Propagation Of Underground-Explosion-Generated Infrasonic Waves Based On The Equations Of Fluid Dynamics: Ground Recordings, Roberto Sabatini, Jonathan B. Snively, Michael P. Hickey, J. L. Garrison
An Analysis Of The Atmospheric Propagation Of Underground-Explosion-Generated Infrasonic Waves Based On The Equations Of Fluid Dynamics: Ground Recordings, Roberto Sabatini, Jonathan B. Snively, Michael P. Hickey, J. L. Garrison
Publications
An investigation on the propagation of underground-explosion-generated infrasonic waves is carried out via numerical simulations of the equations of fluid dynamics. More specifically, the continuity, momentum, and energy conservation equations are solved along with the Herzfeld-Rice equations in order to take into account the effects of vibrational relaxation phenomena. The radiation of acoustic energy by the ground motion caused by underground explosions is initiated by enforcing the equality, at ground level, between the component of the air velocity normal to the Earth's surface and the normal velocity of the ground layer. The velocity of the ground layer is defined semi-empirically …
Steve And The Picket Fence: Evidence Of Feedback-Unstable Magnetosphere-Ionosphere Interaction, Evgeny Mishin, Anatoly Streltsov
Steve And The Picket Fence: Evidence Of Feedback-Unstable Magnetosphere-Ionosphere Interaction, Evgeny Mishin, Anatoly Streltsov
Publications
This paper aims to extend the understanding of Strong Thermal Emission VelocityEnhancement (STEVE) and the Picket Fence related to strong subauroral ion drifts (SAID). Wenumerically demonstrated that precipitating energetic electrons are critical for the structuring of the PicketFence. It is created by feedback-unstable magnetosphere-ionosphere interactions driven by the SAIDelectric field when the Hall conductance created by energetic (≥1 keV) electrons exceeds the Pedersenconductance. We show that thermal excitation of the red-line emission in STEVE is inhibited by inelasticcollisions with molecular nitrogen. Suprathermal (≤500 eV) electrons coming from the turbulentplasmasphere appear to be the major source. We also show that the …
Multilayer Observations And Modeling Of Thunderstorm-Generated Gravity Waves Over The Midwestern United States, C. J. Heale, J. B. Snively, A. N. Bhatt, L. Hoffmann, C. C. Stephan
Multilayer Observations And Modeling Of Thunderstorm-Generated Gravity Waves Over The Midwestern United States, C. J. Heale, J. B. Snively, A. N. Bhatt, L. Hoffmann, C. C. Stephan
Publications
We present multilayer observations and numerical simulations of gravity waves (GWs) generated by a series of Mesoscale Convective Systems over the midwestern United States. Strong semiconcentric GWs were observed and modeled, which couple from their tropospheric sources to the thermosphere, displaying strong nonlinearity indicated by instability, breaking, and formation of turbulent vortices. GWs in the stratosphere display a large range of horizontal scales from 34–400 km; however, the smaller wavelength waves break rapidly in the mesosphere and lower thermosphere. Larger-scale (≥150 km) waves dominate in the thermosphere and display northwestward propagation at 200–300 km altitude, opposing the mean winds. Despite …
Comparison Between Fluid Simulation With Test Particles And 1 Hybrid Simulation For The Kelvin-Helmholtz Instability, Xuanye Ma, Katariina Nykyri, Brandon L. Burkholder, Rachel C. Rice, Peter A. Delamere, Bishwa Neupane
Comparison Between Fluid Simulation With Test Particles And 1 Hybrid Simulation For The Kelvin-Helmholtz Instability, Xuanye Ma, Katariina Nykyri, Brandon L. Burkholder, Rachel C. Rice, Peter A. Delamere, Bishwa Neupane
Publications
A quantitative investigation of plasma transport rate via the Kelvin‐Helmholtz (KH) instability can improve our understanding of solar‐wind‐magnetosphere coupling processes. Simulation studies provide a broad range of transport rates by using different measurements based on different initial conditions and under different plasma descriptions, which makes cross literature comparison difficult. In this study, the KH instability under similar initial and boundary conditions (i.e., applicable to the Earth's magnetopause environment) is simulated by Hall magnetohydrodynamics with test particles and hybrid simulations. Both simulations give similar particle mixing rates. However, plasma is mainly transported through a few big magnetic islands caused by KH‐driven …
Parameterizing Wave‐Driven Vertical Constituent Transport In The Upper Atmosphere, Alan Z. Liu, Chester S. Gardner, Yafang Guo
Parameterizing Wave‐Driven Vertical Constituent Transport In The Upper Atmosphere, Alan Z. Liu, Chester S. Gardner, Yafang Guo
Publications
Dissipating waves contribute to vertical mixing of the atmosphere, alter molecular and eddy diffusion, and induce chemical transport of reactive species. These processes induce strong vertical transport of atmospheric constituents in regions where wave dissipation is significant. The effective wave diffusivity is proportional to the Stokes drift velocity imparted by the spectrum of vertically propagating waves, which is related to the vertical heat and wave energy fluxes. Because the heat flux cannot be derived from wave parameterization schemes employed in most atmospheric models, wave‐driven constituent transport has not been fully incorporated. However, we show in this paper that wave diffusivity …
Effects Of The Hall Conductivity In Ionospheric Heating Experiments, B. Tulegenov, A. V. Streltsov
Effects Of The Hall Conductivity In Ionospheric Heating Experiments, B. Tulegenov, A. V. Streltsov
Publications
We investigate the role of Hall conductivity in ionospheric heating experiments. Ionosphericheating by powerful X-mode waves changes the Hall and Pedersen conductances in theEandDregions,which lead to the generation of ultra-low frequency (ULF)/extremely-low frequency/very low frequencywaves, when the electric field exists in the ionosphere. The importance of the Hall currents in themagnetosphere-ionosphere interactions, carried by ULF waves and field-aligned currents, has beenconsistently overlooked in studies devoted tothe active experiments. Simulations of the three-dimensionaltwo-fluid magnetohydrodynamic (MHD) model, presented in this paper, demonstrate that the Hallconductivity changes (1) the growth rate and the amplitude of ULF waves generated by the heating and (2)the …
Artificial Aurora Produced By Haarp, B. Tulegenov, A. V. Streltsov, E. Kendall, M. Mccarrick, I. Galkin
Artificial Aurora Produced By Haarp, B. Tulegenov, A. V. Streltsov, E. Kendall, M. Mccarrick, I. Galkin
Publications
We present results from the ionospheric heating experiment conducted at the HighFrequency Active Auroral Research Program (HAARP) facility, Alaska, on 12 March 2013. During theexperiment, HAARP transmitted in the direction of the magnetic zenith X-mode 4.57-MHz wave. Thetransmitted power was modulated with the frequency of 0.9 mHz, and it was pointed on a 20-km spot at thealtitude of 120 km. The heating (1) generates disturbances in the magnetic field detected with the fluxgatemagnetometer on the ground and (2) produces bright luminous spots in the ionosphere, observed with theHAARP telescope. Numerical simulations of the 3-D reduced magnetohydrodynamic (MHD) model revealthat these …
Gravity Wave Ducting Observed In The Mesosphere Over Jicamarca, Peru, Gerald A. Lehmacher, Christopher J. Heale, Jonathan B. Snively, Erhan Kudeki, Pablo M. Reyes, Kiwook Lee
Gravity Wave Ducting Observed In The Mesosphere Over Jicamarca, Peru, Gerald A. Lehmacher, Christopher J. Heale, Jonathan B. Snively, Erhan Kudeki, Pablo M. Reyes, Kiwook Lee
Publications
Short-period gravity waves are ubiquitous in the mesosphere, but the vertical structures of their perturbations are difficult to observe. The Jicamarca 50-MHz very high frequency radar allows observations of winds and turbulent scatter with high temporal and vertical resolution. We present a case of a quasi-monochromatic gravity wave with period 520 (±40) s that is likely ducted below a southward wind jet between 68 and 74 km. Above this layer of evanescence, a northward wind enables it to emerge into a more stable layer, where it is refracted to a short vertical wavelength of 2.2 (±0.2) km; data show evidence …
Numerical Modeling Of The Propagation Of Infrasonic Acoustic Waves Through The Turbulent Field Generated By The Breaking Of Mountain Gravity Waves, Michael P. Hickey, Jonathan Snively, C Bailly, J. L. Garrison
Numerical Modeling Of The Propagation Of Infrasonic Acoustic Waves Through The Turbulent Field Generated By The Breaking Of Mountain Gravity Waves, Michael P. Hickey, Jonathan Snively, C Bailly, J. L. Garrison
Publications
The nonlinear propagation of low-frequency acoustic waves through the turbulent fluctuations induced by breaking mountain gravity waves is investigated via 2-D numerical simulations of the Navier-Stokes equations, to understand the effects of atmospheric dynamics on ground-based infrasound measurements. Emphasis is placed on acoustic signals of frequency around 0.1 Hz, traveling through tens-of-kilometers-scale gravity waves and subkilometer-scale turbulence. The sensitivity of the infrasonic phases to small-scale fluctuations is found to depend on the altitudes through which they are refracted toward the Earth. For the considered cases, the dynamics in the stratosphere impact the refracting acoustic waves to a greater extent than …
Application Of A Hybrid Statistical–Dynamical System To Seasonal Prediction Of North American Temperature And Precipitation, Sarah Strazzo, Dan C. Collins, Andrew Schepen, Q. J. Wang, Emily Becker, Liweli Jia
Application Of A Hybrid Statistical–Dynamical System To Seasonal Prediction Of North American Temperature And Precipitation, Sarah Strazzo, Dan C. Collins, Andrew Schepen, Q. J. Wang, Emily Becker, Liweli Jia
Publications
Recent research demonstrates that dynamical models sometimes fail to represent observed teleconnection patterns associated with predictable modes of climate variability. As a result, model forecast skill may be reduced. We address this gap in skill through the application of a Bayesian postprocessing technique—the calibration, bridging, and merging (CBaM) method—which previously has been shown to improve probabilistic seasonal forecast skill over Australia. Calibration models developed from dynamical model reforecasts and observations are employed to statistically correct dynamical model forecasts. Bridging models use dynamical model forecasts of relevant climate modes (e.g., ENSO) as predictors of remote temperature and precipitation. Bridging and calibration …
Latitude And Longitude Dependence Of Ionospheric Tec And Magnetic Perturbations From Infrasonic-Acoustic Waves Generated By Strong Seismic Events, M. D. Zettergren, J. B. Snively
Latitude And Longitude Dependence Of Ionospheric Tec And Magnetic Perturbations From Infrasonic-Acoustic Waves Generated By Strong Seismic Events, M. D. Zettergren, J. B. Snively
Publications
A numerical study of the effects of seismically generated acoustic waves in the ionosphere is conducted using a three-dimensional (3-D) ionospheric model driven by an axisymmetric neutral atmospheric model. A source consistent with the 2011 Tohoku earthquake initial ocean surface uplifting is applied to simulate the subsequent responses. Perturbations in electron density, ion drift, total electron content (TEC), and ground-level magnetic fields are examined. Results reveal strong latitude and longitude dependence of ionospheric TEC, and of ground-level magnetic field perturbations associated with acoustic wave-driven ionospheric dynamo currents. Results also demonstrate that prior two-dimensional models can capture dominant meridional responses of …
Thermal Structure Of The Mesopause Region During The Wadis-2 Rocket Campaign, Raimund Wörl, Boris Strelnikov, Timo P. Viehl, Josef Höffner, Pierre-Dominique Pautet, Michael J. Taylor, Yucheng Zhao, Franz-Josef Lübken
Thermal Structure Of The Mesopause Region During The Wadis-2 Rocket Campaign, Raimund Wörl, Boris Strelnikov, Timo P. Viehl, Josef Höffner, Pierre-Dominique Pautet, Michael J. Taylor, Yucheng Zhao, Franz-Josef Lübken
Publications
This paper presents simultaneous temperature measurements by three independent instruments during the WADIS-2 rocket campaign in northern Norway (69◦ N, 14◦ E) on 5 March 2015. Vertical profiles were measured in situ with the CONE instrument. Continuous mobile IAP Fe lidar (Fe lidar) measurements during a period of 24 h, as well as horizontally resolved temperature maps by the Utah State University (USU) Advanced Mesospheric Temperature Mapper (AMTM) in the mesopause region, are analysed. Vertical and horizontal temperature profiles by all three instruments are in good agreement. A harmonic analysis of the Fe lidar measurements shows the presence …
Vortex: A New Rocketexperiment To Studymesoscale Dynamics At The Turbopause, Gerald A. Lehmacher, Jonathan B. Snively, Aroh Barjatya, Miguel F. Larsen, Michael J. Taylor, Franz-Josef Lübken, Jorge L. Chau
Vortex: A New Rocketexperiment To Studymesoscale Dynamics At The Turbopause, Gerald A. Lehmacher, Jonathan B. Snively, Aroh Barjatya, Miguel F. Larsen, Michael J. Taylor, Franz-Josef Lübken, Jorge L. Chau
Publications
The goal of this new investigation is to better understand gravity waves and their interactions as they propagate from the mesosphere into the lower thermosphere, to characterize the mesoscale wind field, and to identify regions of divergence, vorticity, and stratified turbulence. The Vorticity Experiment (VortEx) will comprise two salvoes of each two sounding rockets scheduled to be launched from Andøya Space Center, Norway in February 2022. The rockets will observe horizontally spaced wind profiles, neutral density and temperature profiles, and plasma densities. Additional information about the background conditions and mesoscale dynamics will be obtained by lidars, meteor radars and a …
Observations Of Reduced Turbulence And Wave Activity In The Arctic Middle Atmosphere Following The January 2015 Sudden Stratospheric Warming, Colin C. Triplett, Aroh Barjatya, Jintai Li, Richard L. Collins, Gerald A. Lehmacher, David C. Fritts, Boris Strelnikov, Franz-Josef Lübken, Brentha Thurairajah, V. Lynn Harvey, Donald L. Hampton, Roger H. Varney
Observations Of Reduced Turbulence And Wave Activity In The Arctic Middle Atmosphere Following The January 2015 Sudden Stratospheric Warming, Colin C. Triplett, Aroh Barjatya, Jintai Li, Richard L. Collins, Gerald A. Lehmacher, David C. Fritts, Boris Strelnikov, Franz-Josef Lübken, Brentha Thurairajah, V. Lynn Harvey, Donald L. Hampton, Roger H. Varney
Publications
Measurements of turbulence and waves were made as part of the Mesosphere-Lower Thermosphere Turbulence Experiment (MTeX) on the night of 25–26 January 2015 at Poker Flat Research Range, Chatanika, Alaska (65°N, 147°W). Rocket-borne ionization gauge measurements revealed turbulence in the 70- to 88-km altitude region with energy dissipation rates between 0.1 and 24 mW/kg with an average value of 2.6 mW/kg. The eddy diffusion coefficient varied between 0.3 and 134 m2/s with an average value of 10 m2/s. Turbulence was detected around mesospheric inversion layers (MILs) in both the topside and bottomside of the MILs. These …
On The Existence Of Ionospheric Feedback Instability In The Earth’S Magnetosphere-Ionosphere System, Anatoly V. Streltsov, Evgeny V. Mishin
On The Existence Of Ionospheric Feedback Instability In The Earth’S Magnetosphere-Ionosphere System, Anatoly V. Streltsov, Evgeny V. Mishin
Publications
The ionospheric feedback instability (IFI) has been considered one of the main generation mechanisms for large-amplitude ultralow frequency waves and small-scale field-aligned currents in the auroral and subauroral regions for more than 40 years. Sydorenko and Rankin (2017, https://doi.org/10.1002/2017GL073415) have recently challenged the very existence of the IFI for any realistic geophysical conditions in the Earth's ionosphere-magnetosphere system. Because this conclusion contradicts numerous theoretical, numerical, and experimental works successfully used IFI to explain and predict results from observations for more than four decades, it deserves special attention. We show that this conclusion is mainly based on the specific ionospheric …
On The Asymmetry Between Upward And Downward Field-Aligned Currents Interacting With The Ionosphere, A. V. Streltsov
On The Asymmetry Between Upward And Downward Field-Aligned Currents Interacting With The Ionosphere, A. V. Streltsov
Publications
The paper presents results from the numerical study of the magnetosphere-ionosphere interactions driven by the large-scale electric field in the magnetically conjugate, high-latitude regions of northern and southern hemispheres. Simulations of the two-fluid MHD model demonstrate that these interactions can lead to a generation of a system of small-scale, intense field-aligned currents with a significant difference in size and amplitude between the upward and downward currents. In particular, in both hemispheres, the downward currents (where the electrons are flowing from the ionosphere) become more narrow and intense than the adjacent upward currents. At high latitudes, the field-aligned currents are closely …
Momentum Flux Spectra Of A Mountain Wave Event Over New Zealand, Katrina Bossert, David C. Fritts, Christopher J. Heale, Stephen D. Eckermann, John M. C. Plane, Jonathan B. Snively, Bifford P. Williams, Iain M. Reid, Damian J. Murphy, Andrew J. Spargo, Andrew D. Mackinnon
Momentum Flux Spectra Of A Mountain Wave Event Over New Zealand, Katrina Bossert, David C. Fritts, Christopher J. Heale, Stephen D. Eckermann, John M. C. Plane, Jonathan B. Snively, Bifford P. Williams, Iain M. Reid, Damian J. Murphy, Andrew J. Spargo, Andrew D. Mackinnon
Publications
During the Deep Propagating Gravity Wave Experiment (DEEPWAVE) 13 July 2014 research flight over the South Island of New Zealand, a multiscale spectrum of mountain waves (MWs) was observed. High-resolution measurements of sodium densities were available from ~70 to 100 km for the duration of this flight. A comprehensive technique is presented for obtaining temperature perturbations, T′, from sodium mixing ratios over a range of altitudes, and these T′ were used to calculate the momentum flux (MF) spectra with respect to horizontal wavelengths, λH, for each flight segment. Spectral analysis revealed MWs with spectral power centered at λH of ~80, …
Ultralow Frequency Electrodynamics Of Magnetosphere-Ionosphere Interactions Near The Plasmapause During Substorms, Anatoly V. Streltsov, Evgeny V. Mishin
Ultralow Frequency Electrodynamics Of Magnetosphere-Ionosphere Interactions Near The Plasmapause During Substorms, Anatoly V. Streltsov, Evgeny V. Mishin
Publications
Ultra low frequency (ULF) electromagnetic waves have been regularly observed by the CRRES, Cluster, and Van Allen Probes satellites near the plasmapause during substorms. Frequently, the small-scale waves are detected together with a large-scale quasi-stationary electric field collocating with mesoscale plasma flows penetrating into the plasmasphere. These observations suggest that the plasmapause plays an important role in the conversion of the kinetic energy of energetic particles moving toward the Earth from the reconnection site in the magnetotail into a large-scale electric field. The field penetrates along the magnetic field into the ionosphere and generates small-scale, shear Alfvén waves and field-aligned …