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Oceanography and Atmospheric Sciences and Meteorology

Embry-Riddle Aeronautical University

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Articles 1 - 30 of 320

Full-Text Articles in Physical Sciences and Mathematics

Interferometric Imaging With Eiscat_3d For Fine-Scale In-Beam Incoherent Scatter Spectra Measurements, M. Zettergren, Devin Huyghebaert, Björn Gustavsson, Juha Vierinen, Andreas Kvammen, John Swoboda, Ilkka Virtanen, Spencer Hatch, Karl M. Laundal Mar 2024

Interferometric Imaging With Eiscat_3d For Fine-Scale In-Beam Incoherent Scatter Spectra Measurements, M. Zettergren, Devin Huyghebaert, Björn Gustavsson, Juha Vierinen, Andreas Kvammen, John Swoboda, Ilkka Virtanen, Spencer Hatch, Karl M. Laundal

Publications

The 233 MHz EISCAT_3D radar system currently under construction in northern Fennoscandia will be able to resolve ionospheric structures smaller than the transmit beam dimensions through the use of interferometric imaging. This capability is made possible by the modular design and digitization of the 119 91-antenna panels located at the main Skibotn site. The main array consists of a cluster of 109 panels, with 10 outlier panels producing unique interferometry baselines. In the present study synthesized incoherent scatter radar signal measurements are used for interferometric imaging analysis with the EISCAT_3D system. The Geospace Environment Model of Ion-Neutral Interactions (GEMINI) model …

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Toward The Unified Theory Of Said-Linked Subauroral Arcs, Evgeny V. Mishin, Anatoly V. Streltsov Jan 2024

Toward The Unified Theory Of Said-Linked Subauroral Arcs, Evgeny V. Mishin, Anatoly V. Streltsov

Publications

We present a unified approach to subauroral arcs within intense subauroral ion drifts (SAID), which explains the observed transition of a precursor Stable Auroral Red (SAR) arc into Strong Thermal Emission Velocity Enhancement (STEVE). This approach is based on the short-circuiting concept of fasttime SAID as an integral part of a magnetospheric voltage generator between the innermost boundaries of the freshly injected plasma sheet electrons and ring current ions. Here, enhanced plasma turbulence rapidly heats the bulk plasma and accelerates suprathermal non-Maxwellian “tails.” Heat and suprathermal electron transport rapidly elevate the ionospheric electron temperature—the source of a bright SAR arc. …

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Application Of Density Altitude Climatology To General Aviation Impacts, Thomas A. Guinn Ph.D., Daniel J. Halperin Ph.D., Sarah Strazzo Ph.D. Jan 2024

Application Of Density Altitude Climatology To General Aviation Impacts, Thomas A. Guinn Ph.D., Daniel J. Halperin Ph.D., Sarah Strazzo Ph.D.

Journal of Aviation/Aerospace Education & Research

Density altitude (DA) plays a key role in flight safety because it helps pilots anticipate poor aircraft performance when temperatures are warmer than standard. In this study, a 30-year climatology of DA for the conterminous United States was created using the fifth-generation European Centre for Medium-Range Weather Forecasts atmospheric reanalysis of the global climate (ERA5) dataset was applied to four separate DA-based, aircraft-performance, rules-of-thumb for general aviation (GA) flight. The goal was to demonstrate a technique to create educational visualization tools showing the variation of operational flight impacts with both month and location. Four such parameters were chosen to show …

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Multi-Layer Evolution Of Acoustic-Gravity Waves And Ionospheric Disturbances Over The United States After The 2022 Hunga Tonga Volcano Eruption, P. A. Inchin, A. Bhatt, S. A. Cummer, S. D. Eckermann, B. J. Harding, J. Ma, J. J. Makela, J B. Snively Dec 2023

Multi-Layer Evolution Of Acoustic-Gravity Waves And Ionospheric Disturbances Over The United States After The 2022 Hunga Tonga Volcano Eruption, P. A. Inchin, A. Bhatt, S. A. Cummer, S. D. Eckermann, B. J. Harding, J. Ma, J. J. Makela, J B. Snively

Publications

e Hunga-Tonga Hunga-Ha'apai volcano underwent a series of large-magnitude eruptions that generated in the atmosphere. We investigate the spatial and temporal evolutions of fluctuations driven by atmospheric acoustic-gravity waves (AGWs) and, in particular, the Lamb wave modes in high spatial resolution data sets measured over the Continental United States (CONUS), complemented with data over the Americas and the Pacific. Along with >800 barometer sites, tropospheric observations, and Total Electron Content data from >3,000 receivers, we report detections of volcano-induced AGWs in mesopause and ionosphere-thermosphere airglow imagery and Fabry-Perot interferometry. We also report unique AGW signatures in the ionospheric D-region, measured …

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Impact Of Weather Factors On Airport Arrival Rates: Application Of Machine Learning In Air Transportation, Robert W. Maxson, Dothang Truong, Woojin Choi Dec 2023

Impact Of Weather Factors On Airport Arrival Rates: Application Of Machine Learning In Air Transportation, Robert W. Maxson, Dothang Truong, Woojin Choi

Publications

Weather is responsible for approximately 70% of air transportation delays in the National Airspace System, and delays resulting from convective weather alone cost airlines and passengers millions of dollars each year due to delays that could be avoided. This research sought to establish relationships between environmental variables and airport efficiency estimates by data mining archived weather and airport performance data at ten geographically and climatologically different airports. Several meaningful relationships were discovered from six out of ten airports using various machine learning methods within an overarching data mining protocol, and the developed models were tested using historical data.

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Gravity Waves Generated By The Hunga Tonga-Hunga Ha‘Apai Volcanic Eruption And Their Global Propagation In The Mesosphere/Lower Thermosphere Observed By Meteor Radars And Modeled With The High-Altitude General Mechanistic Circulation Model, Gunter Stober, Sharon L. Vadas, Erich Becker, Alan Liu, Diego Janches, Zishun Qiao, Et.Al Oct 2023

Gravity Waves Generated By The Hunga Tonga-Hunga Ha‘Apai Volcanic Eruption And Their Global Propagation In The Mesosphere/Lower Thermosphere Observed By Meteor Radars And Modeled With The High-Altitude General Mechanistic Circulation Model, Gunter Stober, Sharon L. Vadas, Erich Becker, Alan Liu, Diego Janches, Zishun Qiao, Et.Al

Publications

The Hunga Tonga-Hunga Ha‘apai volcano erupted on 15th January 2022, launching Lamb waves and gravity waves into the atmosphere. In this study, we present results using 13 globally distributed meteor radars and identify the volcanic- caused gravity waves in the mesospheric/lower thermospheric winds. Leveraging the High-Altitude Mechanistic General Circulation Model (HIAMCM), we compare the global propagation of these gravity waves. We observed an eastward propagating gravity wave packet with an observed phase speed of 240±5.7 m/s and a westward propagating gravity wave with an observed phase speed of 166.5 ±6.4 m/s. We identified these waves in the HIAMCM and obtained …

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On The Propagation Of Whistler-Mode Waves In The 2 Magnetic Ducts, Salman A. Nejad, Anatoly V. Streltsov Sep 2023

On The Propagation Of Whistler-Mode Waves In The 2 Magnetic Ducts, Salman A. Nejad, Anatoly V. Streltsov

Publications

This paper studies extremely-low frequency (ELF) whistler-mode waves’ behavior within small-scale magnetic field irregularities in the Earth’s magnetosphere, known as magnetic ducts. Based on the magnetic fields’ magnitude inside and outside these ducts, they are categorized as high-magnetic ducts (HBD) and low-magnetic ducts (LBD). Using the whistler-mode dispersion relation analysis, our primary focus is to show that LBDs are prone to leak electromagnetic energy outside the duct. We further investigate the hypothesis that whistlers can propagate within LBDs without any signal loss when the width of the duct corresponds to an integer multiple of the perpendicular wavelengths of the waves …

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A "Boreing" Night Of Observations Of The Upper Mesosphere And Lower Thermosphere Over The Andes Lidar Observatory, J. H. Hecht, Alan Liu, D. C. Fritts, R. L. Walterscheid, L. J. Gelinas, R. J. Rudy Sep 2023

A "Boreing" Night Of Observations Of The Upper Mesosphere And Lower Thermosphere Over The Andes Lidar Observatory, J. H. Hecht, Alan Liu, D. C. Fritts, R. L. Walterscheid, L. J. Gelinas, R. J. Rudy

Publications

A very high-spatial resolution (∼21-23 m pixel at 85 km altitude) OH airglow imager at the Andes Lidar Observatory at Cerro Pach´on, Chile observed considerable ducted wave activity on the night of October 29-30, 2016. This instrument was collocated with a Na wind-temperature lidar that provided data revealing the occurrence of strong ducts. A large field of view OH and greenline airglow imager showed waves present over a vertical extent consistent with the altitudes of the ducting features identified in the lidar profiles. While waves that appeared to be ducted were seen in all imagers throughout the observation interval, the …

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Whistler-Mode Waves In Magnetic Ducts, Anatoly V. Streltsov, Salman A. Nejad Aug 2023

Whistler-Mode Waves In Magnetic Ducts, Anatoly V. Streltsov, Salman A. Nejad

Publications

Observations from the NASA MMS satellites show packages of ELF whistler-mode waves localized inside the small-scale irregularities of the magnetic field. These irregularities are formed by the narrow field-aligned channels where the magnitude of the background magnetic field inside the channel is greater or less than outside. By analogy with the classical density ducts, we introduce the high-B duct (HBD), where the magnitude of the field inside the channel is greater than the outside, and the low-B duct (LBD), where the magnitude of the field inside the channel is less than the outside. We investigate the guiding of the ELF …

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Hyper-Local Weather Predictions With The Enhanced General Urban Area Microclimate Predictions Tool, Kevin A. Adkins, William Becker, Sricharan Ayyalasomayajula, Steven Lavenstein, Kleoniki Vlachou, David Miller, Marc Compere, Avinash Muthu Krishnan, Nickolas Macchiarella Jun 2023

Hyper-Local Weather Predictions With The Enhanced General Urban Area Microclimate Predictions Tool, Kevin A. Adkins, William Becker, Sricharan Ayyalasomayajula, Steven Lavenstein, Kleoniki Vlachou, David Miller, Marc Compere, Avinash Muthu Krishnan, Nickolas Macchiarella

Publications

This paper presents enhancements to, and the demonstration of, the General Urban area Microclimate Predictions tool (GUMP), which is designed to provide hyper-local weather predictions by combining machine-learning (ML) models and computational fluid dynamic (CFD) simulations. For the further development and demonstration of GUMP, the Embry–Riddle Aeronautical University (ERAU) campus was used as a test environment. Local weather sensors provided data to train ML models, and CFD models of urban- and suburban-like areas of ERAU’s campus were created and iterated through with a wide assortment of inlet wind speed and direction combinations. ML weather sensor predictions were combined with best-fit …

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The Effect Of Advection On The Three Dimensional Distribution Of Turbulent Kinetic Energy And Its Generation In Idealized Tropical Cyclone Simulations, Joshua B. Wadler, David S. Nolan, Jun A. Zhang, Lynn K. Shay, Joseph B. Olsen, Joseph J. Cione May 2023

The Effect Of Advection On The Three Dimensional Distribution Of Turbulent Kinetic Energy And Its Generation In Idealized Tropical Cyclone Simulations, Joshua B. Wadler, David S. Nolan, Jun A. Zhang, Lynn K. Shay, Joseph B. Olsen, Joseph J. Cione

Publications

The distribution of turbulent kinetic energy (TKE) and its budget terms is estimated in simulated tropical cyclones (TCs) of various intensities. Each simulated TC is subject to storm motion, wind shear, and oceanic coupling. Different storm intensities are achieved through different ocean profiles in the model initialization. For each oceanic profile, the atmospheric simulations are performed with and without TKE advection. In all simulations, the TKE is maximized at low levels (i.e., below 1 km) and ∼0.5 km radially inward of the azimuthal-mean radius of maximum wind speed at 1-km height. As in a previous study, the axisymmetric TKE decreases …

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Accelerating Atmospheric Gravity Wave Simulations Using Machine Learning: Kelvin-Helmholtz Instability And Mountain Wave Sources Driving Gravity Wave Breaking And Secondary Gravity Wave Generation, Wenjun Dong, David Fritts, Alan Z. Liu, Hanli Liu, Jonathan Snively Apr 2023

Accelerating Atmospheric Gravity Wave Simulations Using Machine Learning: Kelvin-Helmholtz Instability And Mountain Wave Sources Driving Gravity Wave Breaking And Secondary Gravity Wave Generation, Wenjun Dong, David Fritts, Alan Z. Liu, Hanli Liu, Jonathan Snively

Publications

Gravity waves (GWs) and their associated multi-scale dynamics are known to play fundamental roles in energy and momentum transport and deposition processes throughout the atmosphere. We describe an initial, two-dimensional (2-D), machine learning model – the Compressible Atmosphere Model Network (CAMNet) - intended as a first step toward a more general, three-dimensional, highly-efficient, model for applications to nonlinear GW dynamics description. CAMNet employs a physics-informed neural operator to dramatically accelerate GW and secondary GW (SGW) simulations applied to two GW sources to date. CAMNet is trained on high-resolution simulations by the state-of-the-art model Complex Geometry Compressible Atmosphere Model (CGCAM). Two …

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Gravity Waves Emitted From Kelvin-Helmholtz Instabilities, Alan Z. Liu, Wenjun Dong, David C. Fritts, Thomas S. Lunda, Han-Li Liu Apr 2023

Gravity Waves Emitted From Kelvin-Helmholtz Instabilities, Alan Z. Liu, Wenjun Dong, David C. Fritts, Thomas S. Lunda, Han-Li Liu

Publications

Fritts, Wang, Lund, and Thorpe (2022, https://doi.org/10.1017/jfm.2021.1085) and Fritts, Wang, Thorpe, and Lund (2022, https://doi.org/10.1017/jfm.2021.1086) described a 3-dimensional direct numerical simulation of interacting Kelvin-Helmholtz instability (KHI) billows and resulting tube and knot (T&K) dynamics that arise at a stratified shear layer defined by an idealized, large-amplitude inertia-gravity wave. Using similar initial conditions, we performed a high-resolution compressible simulation to explore the emission of GWs by these dynamics. The simulation confirms that such shear can induce strong KHI with large horizontal scales and billow depths that readily emit GWs having high frequencies, small horizontal wavelengths, and large vertical group velocities. The …

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Analysis Of Energy Transfer Among Background Flow, Gravity Waves And Turbulence In The Mesopause Region In The Process Of Gravity Wave Breaking From A High-Resolution Atmospheric Model, Alan Z. Liu, Fan Yang, Christopher James Heale, Jonathan Brian Snively, Wenjun Dong, Thomas Lund Mar 2023

Analysis Of Energy Transfer Among Background Flow, Gravity Waves And Turbulence In The Mesopause Region In The Process Of Gravity Wave Breaking From A High-Resolution Atmospheric Model, Alan Z. Liu, Fan Yang, Christopher James Heale, Jonathan Brian Snively, Wenjun Dong, Thomas Lund

Publications

We conducted an analysis of the process of GW breaking from an energy perspective using the output from a high-resolution compressible atmospheric model. The investigation focused on the energy conversion and transfer that occur during the GW breaking. The total change in kinetic energy and the amount of energy converted to internal energy and potential energy within a selected region were calculated.
Prior to GW breaking, part of the potential energy is converted into kinetic energy, most of which is transported out of the chosen region. After the GW breaks and turbulence develops, part of the potential energy is converted …

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Analysis Of Energy Transfer Among Background Flow, Gravity Waves And Turbulence In The Mesopause Region In The Process Of Gravity Wave Breaking From A High-Resolution Atmospheric Model, Fan Yang, Alan Z. Liu, Christopher J. Heale, Jonathan B. Snively, Wenjun Dong, Thomas Lund Mar 2023

Analysis Of Energy Transfer Among Background Flow, Gravity Waves And Turbulence In The Mesopause Region In The Process Of Gravity Wave Breaking From A High-Resolution Atmospheric Model, Fan Yang, Alan Z. Liu, Christopher J. Heale, Jonathan B. Snively, Wenjun Dong, Thomas Lund

Publications

We conducted an analysis of the process of GW breaking from an energy perspective using the output from a high-resolution compressible atmospheric model. The investigation focused on the energy conversion and transfer that occur during the GW breaking. The total change in kinetic energy and the amount of energy converted to internal energy and potential energy within a selected region were calculated. Prior to GW breaking, part of the potential energy is converted into kinetic energy, most of which is transported out of the chosen region. After the GW breaks and turbulence develops, part of the potential energy is converted …

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Gravity Wave Drag Parameterizations For Earth’S Atmosphere, Christopher J. Heale, Christopher G. Kruse, Jadwiga H. Richter, M. Joan Alexander, Julio T. Bacmeister, Junhong Wei Jan 2023

Gravity Wave Drag Parameterizations For Earth’S Atmosphere, Christopher J. Heale, Christopher G. Kruse, Jadwiga H. Richter, M. Joan Alexander, Julio T. Bacmeister, Junhong Wei

Publications

Atmospheric gravity waves (GWs), or buoyancy waves, transport momentum and energy through Earth’s atmosphere. GWs are important at nearly all levels of the atmosphere, though, the momentum they transport is particularly important in general circulation of the middle and upper atmosphere. Primary sources of atmospheric GWs are flow over mountains, moist convection, and imbalances in jet/frontal systems. Secondary GWs can also be generated as a result of dissipation of a primary GWs. Gravity waves typically have horizontal wavelengths of 10’s to 100’s of kilometers, though, they can have scales of 1’s to 1000’s of kilometers as well. Current effective resolutions …

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Using Micro Satellites To Assess The Impact Of Algae Growth On Global Warming, Hursh, Vanessa Jan 2023

Using Micro Satellites To Assess The Impact Of Algae Growth On Global Warming, Hursh, Vanessa

Student Works

Data gathered from microsatellites can inform policymakers and environmental agencies about the impact of algae on global warming. It can guide the development of strategies to mitigate or harness the potential benefits of algae growth.

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Alternatives To Reducing Aviation Fuel-Burn With Technology: Fully Electric Autonomous Taxibot, Denzil Neo Jan 2023

Alternatives To Reducing Aviation Fuel-Burn With Technology: Fully Electric Autonomous Taxibot, Denzil Neo

Student Works

Aircraft taxiing operations in the aerodrome were identified to consume the most jet fuel apart from the cruise phase of the flight. This was also well supported by various research associating taxi operations at large, congested airports, with high jet fuel consumption, high carbon emissions, and noise pollution. Existing literature recognised the potential to address the environmental issues of aerodrome taxi operations by operating External or Onboard Aircraft Ground Propulsion Systems (AGPS). Designed to power aircraft with sources other than their main engines, external Aircraft Ground Power Systems (AGPS) have shown the potential to significantly cut jet fuel consumption and …

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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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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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Dynamics Of Atmospheric Gravity Wave Breaking In The Mesopause Region, Fan Yang Oct 2022

Dynamics Of Atmospheric Gravity Wave Breaking In The Mesopause Region, Fan Yang

Doctoral Dissertations and Master's Theses

GWs significantly impact the Mesosphere and Lower Thermosphere (MLT), and as a consequence of GW breaking, atmospheric turbulence plays an essential role in the mixing and transport of momentum, mass, and chemical materials in MLT. The main focus of this research for the fulfillment of the proposed Ph.D. dissertation is to improve the understanding of the dynamic process of wave breaking and their effects in the mesopause region above Andes Lidar Observatory (30.2◦ S, 70.7◦ W). A few scientific topics related to GW break- ing are addressed. What are the probabilities of the atmosphere becoming convectively or dynamically unstable in …

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Kinetic Modeling Of Ionospheric Outflows Observed By The Visions-1 Sounding Rocket, Robert M. Albarran Ii Sep 2022

Kinetic Modeling Of Ionospheric Outflows Observed By The Visions-1 Sounding Rocket, Robert M. Albarran Ii

Doctoral Dissertations and Master's Theses

Plasma escape from the high-latitude ionosphere (ion outflow) serves as a significant source of heavy plasma to magnetospheric plasma sheet and ring current regions. Outflows alter mass density and reconnection rates, hence global responses of the magnetosphere. The VISIONS-1 (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) sounding rocket was launched on Feb. 7, 2013 at 8:21 UTC from Poker Flat, Alaska, into an auroral substorm with the objective of identifying the drivers and dynamics of nightside ion outflow at altitudes where it is initiated, below 1000 km. Energetic ion data from the VISIONS-1 polar cap boundary crossing …

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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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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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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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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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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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