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Atmospheric Sciences

Embry-Riddle Aeronautical University

2019

Articles 1 - 17 of 17

Full-Text Articles in Physical Sciences and Mathematics

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 Dec 2019

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 …

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Steve And The Picket Fence: Evidence Of Feedback-Unstable Magnetosphere-Ionosphere Interaction, Evgeny Mishin, Anatoly Streltsov Dec 2019

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 …

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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 Dec 2019

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 …

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How Airport Construction Will Evolve With The Increased Effects Of Climate Change, Xavier M. Ashley Nov 2019

How Airport Construction Will Evolve With The Increased Effects Of Climate Change, Xavier M. Ashley

Beyond: Undergraduate Research Journal

This report addressed the effects rising global temperatures resulting from climate change have had on flight operations in their entirety. The research objective was to discover what methods could enhance climate adaptation in airport construction, as higher mean-surface temperatures have an increasingly negative effect on aircraft performance. The findings would primarily be of interest to the Federal Aviation Administration (FAA) Primary Office presiding over the planning and development of airports. Overall, the report provided a comprehensive analysis of global warming’s effects on aviation, including the implications of degraded aircraft performance and sea-level rise for coastal airports. Additionally, it examined comparative …

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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 Aug 2019

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 …

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Parameterizing Wave‐Driven Vertical Constituent Transport In The Upper Atmosphere, Alan Z. Liu, Chester S. Gardner, Yafang Guo Jun 2019

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 …

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Effects Of The Hall Conductivity In Ionospheric Heating Experiments, B. Tulegenov, A. V. Streltsov May 2019

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 …

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Artificial Aurora Produced By Haarp, B. Tulegenov, A. V. Streltsov, E. Kendall, M. Mccarrick, I. Galkin Apr 2019

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 …

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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 Apr 2019

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 …

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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 Apr 2019

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 …

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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 Feb 2019

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 …

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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 Jan 2019

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 …

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Urban Flow And Small Unmanned Aerial System Operations In The Built Environment, Kevin A. Adkins Jan 2019

Urban Flow And Small Unmanned Aerial System Operations In The Built Environment, Kevin A. Adkins

International Journal of Aviation, Aeronautics, and Aerospace

The Federal Aviation Administration (FAA) has put forth a set of regulations (Part 107) that govern small unmanned aerial system (sUAS) operations. These regulations restrict unmanned aircraft (UA) from flying over people and their operation to within visual line of sight (VLOS). However, as new applications for unmanned aerial systems (UAS) are discovered, their capabilities improve, and regulations evolve, there is an increasing desire to undertake urban operations, such as urban air mobility, package delivery, infrastructure inspection, and surveillance. This built environment poses new weather hazards that include enhanced wind shear and turbulence. The smaller physical dimensions, lower mass and …

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On Atmospheric Lapse Rates, Nihad E. Daidzic Jan 2019

On Atmospheric Lapse Rates, Nihad E. Daidzic

International Journal of Aviation, Aeronautics, and Aerospace

We have derived and summarized and most important atmospheric temperature lapse rates. ALRs essentially govern vertical atmospheric air stability and creation of some cloud types. The sensitivity analysis of various atmospheric lapse rates and their dependence on actual ideal-gas air properties and gravitational attraction was conducted for the first time to the best of our knowledge. SALR, which has DALR as the upper asymptote, showed steepest decrease at around 9 degrees Celsius then flattening out and apparently approaching another asymptotic solution which has not been investigated as it falls outside of the terrestrial temperature range. ISA lapse rates are adopted …

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Adding Value To Numerical Weather Predictions For The Aviation Industry In South Africa., Quinton Jacobs Mr., Willem A. Landman Prof. Jan 2019

Adding Value To Numerical Weather Predictions For The Aviation Industry In South Africa., Quinton Jacobs Mr., Willem A. Landman Prof.

International Journal of Aviation, Aeronautics, and Aerospace

The main objective of this study is to determine whether human forecasters at the main airports of South Africa add value to the raw numerical weather prediction model output when they provide forecast services to the aviation industry. Dataset pairs of weather observations made at these airports and terminal aerodrome forecasts are constructed for three forecast systems: the human forecasters, persistence forecast and the raw output from the 12 km resolution Unified Model administered by the South African Weather Service. These three dataset pairs are independently evaluated by a forecast verification system developed at the South African Weather Service. A …

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A New Model For Lifting Condensation Levels Estimation, Nihad E. Daidzic Ph.D., Sc.D. Jan 2019

A New Model For Lifting Condensation Levels Estimation, Nihad E. Daidzic Ph.D., Sc.D.

International Journal of Aviation, Aeronautics, and Aerospace

Knowledge of and the ability to predict lifting condensation levels (LCL) is important ingredient in weather predictions, cloud formation, planetary albedo and Earth’s energy balance. It is also essential topic in aviation safety and flight operations. In this article, we derive a new model of LCL and compare it to some older commonly-used models. This includes also the recently published Romps’ (2017) model. The new model presented here includes dependence, however weak, of the surface atmospheric pressure and the specific humidity on the LCL height and temperature. Such is not the case with widely used models and expressions by Espy …

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Vortex: A New Rocketexperiment To Studymesoscale Dynamics At The Turbopause, Gerald A. Lehmacher, Miguel F. Larsen, Michael J. Taylor, Jonathan B. Snively, Aroh Barjatya, Franz-Josef Lübken, Jorge L. Chau Jan 2019

Vortex: A New Rocketexperiment To Studymesoscale Dynamics At The Turbopause, Gerald A. Lehmacher, Miguel F. Larsen, Michael J. Taylor, Jonathan B. Snively, Aroh Barjatya, 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 …

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