Physical Sciences and Mathematics Commons^™

Dynamics Of Density Cavities Generated By Frictional Heating: Formation, Distortion, And Instability, M. D. Zettergren, J. L. Semeter, H. Dahlgren

Publications

A simulation study of the generation and evolution of mesoscale density cavities in the polar ionosphere is conducted using a time-dependent, nonlinear, quasi-electrostatic model. The model demonstrates that density cavities, generated by frictional heating, can form in as little as 90 s due to strong electric fields of ∼120 mV/m, which are sometimes observed near auroral zone and polar cap arcs. Asymmetric density cavity features and strong plasma density gradients perpendicular to the geomagnetic field are naturally generated as a consequence of the strong convection and finite extent of the auroral feature. The walls of the auroral density cavities are …

Enhancing Quality Assurance Using Virtual Design Engineering: Case Study Of Space Shuttle Challenger, Kouroush Jenab, Scot Paterson

International Journal of Aviation, Aeronautics, and Aerospace

Virtual Design Engineering is an emerging method of increasing quality of systems. Including Virtual Design as a part of the traditional established Failure Mode, Effects, and Criticality Analysis process greatly enhances hazard and risk analysis while reducing overall costs. In this study these enhancements are explored and expanded upon to discover how overall system quality could be increased and all stakeholders could more accurately understand the hazards involved. Stakeholder misunderstanding or misapplication of hazards is of great importance to complex systems. An illustrative example of how these factors could have changed the outcome of a real-world engineering failure is provided.

Examining Unmanned Aerial System Threats & Defenses: A Conceptual Analysis, Ryan J. Wallace, Jon M. Loffi

International Journal of Aviation, Aeronautics, and Aerospace

The integration of unmanned aerial systems (UAS) into the already complex global aviation system presents new and unique hazards. While many studies have addressed the potential safety concerns of UAS integration, little research has been dedicated to the potential security implications. This study sought to identify potential uses and adaptations of civil UAS systems as weapons of terrorism or crime and potential UAS defenses. Researchers examined 68 academic studies, unclassified government reports, and news articles using Conceptual Analysis to systematically capture and categorize various threats. Using the collected data, researchers developed a UAS threat model for categorically evaluating potential threats. …

Ionospheric Response To Infrasonic-Acoustic Waves Generated By Natural Hazard Events, M. D. Zettergren, J. B. Snively

Publications

"Recent measurements of GPS-derived total electron content (TEC) reveal acoustic wave periods of ∼1–4 min in the F region ionosphere following natural hazard events, such as earthquakes, severe weather, and volcanoes. Here we simulate the ionospheric responses to infrasonic-acoustic waves, generated by vertical accelerations at the Earth’s surface or within the lower atmosphere, using a compressible atmospheric dynamics model to perturb a multifluid ionospheric model. Response dependencies on wave source geometry and spectrum are investigated at middle, low, and equatorial latitudes. Results suggest constraints on wave amplitudes that are consistent with observations and that provide insight on the geographical variability …

Self-Accleration And Instability Of Gravity Wave Packets: 1. Effects Of Temporal Localization, David C. Fritts, Brian Laughman, Thomas S. Lund, Jonathan B. Snively

Publications

"An anelastic numerical model is used to explore the dynamics accompanying the attainment of large amplitudes by gravity waves (GWs) that are localized in altitude and time. GW momentum transport induces mean flow variations accompanying a GW packet that grows exponentially with altitude, is localized in altitude, and induces significant GW phase speed, and phase, variations across the GW packet. These variations arise because the GW occupies the region undergoing accelerations, with the induced phase speed variations referred to as “self-acceleration.” Results presented here reveal that self-acceleration of a GW packet localized in time and altitude ultimately leads to stalling …

Aviation Bird Hazard In Nexrad Dual Polarization Weather Radar Confirmed By Visual Observations, Bradley M. Muller, Frederick R. Mosher, Christopher G. Herbster, Anthony T. Brickhouse

International Journal of Aviation, Aeronautics, and Aerospace

Birds represent a significant hazard to flying aircraft as illustrated by the “Miracle on the Hudson” encounter in 2009 between U.S. Airways Flight 1549 and a flock of Canada Geese, forcing the flight to ditch in the river. Birds are common in the skies over Florida during the spring migration season, and often appear in the National Weather Service’s (NWS) NEXRAD weather radar imagery as an easily recognizable signature known as a “roost ring.” This paper presents a NEXRAD roost ring case in central Florida in a rare instance where the signatures were confirmed by visual observations of the birds. …

Global Optimized Isothermal And Nonlinear Models Of Earth’S Standard Atmosphere, Nihad E. Daidzic, Ph.D.,

International Journal of Aviation, Aeronautics, and Aerospace

Both, a global isothermal temperature model and a nonlinear quadratic temperature model of the ISA was developed and presented here. Constrained optimization techniques in conjunction with the least-square-root approximations were used to design best-fit isothermal models for ISA pressure and density changes up to 47 geopotential km for NLPAM, and 86 orthometric km for ISOAM respectively. The mass of the dry atmosphere and the relevant fractional-mass scale heights have been computed utilizing the very accurate eight-point Gauss-Legendre numerical quadrature for both ISOAM and NLPAM. Both, the ISOAM and the NLPAM represent viable alternatives to ISA in many practical applications and …

The Life Cycle Of Instability Features Measured From The Andes Lidar Observatory Over Cerro Pachon On 24 March 2012, J. H. Hecht, K. Wan, Lynette Gelinas, David Fritts, R. L. Walterscheid, R. J. Rudy, Alan Liu, Steven J. Franke, Fabio Vargas, P. -D. Pautet, Michael Taylor, Gary Swenson,

Publications

The Aerospace Corporation's Nightglow Imager (ANI) observes nighttime OH emission (near 1.6 µm) every 2 s over an approximate 73¬∞ field of view. ANI had previously been used to study instability features seen over Maui. Here we describe observations of instabilities seen from 5 to 8 UT on 24 March 2012 over Cerro Pachon, Chile, and compare them with previous results from Maui, with theory, and with Direct Numerical Simulations (DNS). The atmosphere had reduced stability because of the large negative temperature gradients measured by a Na lidar. Thus, regions of dynamical and convective instabilities are expected to form, depending …

Bio-Fuel Alternatives In South African Airways (Saa) Operations - Is It An Effective Response To Vulnerability Over Carbon Taxes And Penalty?, Daniel Kwasi Adjekum

International Journal of Aviation, Aeronautics, and Aerospace

The paper did a comparative analysis of the carbon emission and European Union Emission Trading Surcharges (EU ETS) of South African Airways (SAA) current fleet that used aviation jet A1 fuel and the same fleet if it had used a 25% bio-fuel ‘drop in’ for the European routes within the first quarter of the 2014 flying year (FY 14). Operational data in terms of the flight scheduled, aircraft type, total time enroute, route stage length, passenger estimates were obtained through SAA’s flight operations website. An independent t–test was conducted to compare means of the emissions. The mean carbon dioxide …

A Meteorological Analysis Of The 2013 Alberta Flood: Antecendent Large-Scale Flow Pattern And Synoptic-Dynamic Characteristics, Shawn M. Milrad, John R. Gyakum, Eyad H. Atallah

Publications

The 19–21 June 2013 Alberta flood was the costliest (CAD $6 billion) natural disaster in Canadian history. The flood was caused by a combination of above-normal spring snowmelt in the Canadian Rockies, large antecedent precipitation, and an extreme rainfall event on 19–21 June that produced rainfall totals of 76 mm in Calgary and 91 mm in the foothills. As is typical of flash floods along the Front Range of the Rocky Mountains, rapidly rising streamflow proceeded to move downhill (eastward) into Calgary.

A meteorological analysis traces an antecedent Rossby wave train across the North Pacific Ocean, starting with intense baroclinic …

Design And Validation Of Hardware-In-The-Loop Testbed For Proximity Operations Payloads, Kristia K. Harris

Doctoral Dissertations and Master's Theses

The research presented here is a new testbed design for CubeSat and payload testing and development. This research demonstrates a low-cost, hardware-in-the-loop testing apparatus for use with university CubeSat programs for testing throughout the different levels of the development process. The average university CubeSat program undergoes very little hardware-in-the-loop testing. Most of the focus is the targeted towards performance testing and environmental testing which occur after completion the development process. This research shows that, for minimal schedule and cost impact, testing can occur early in the development process. The testbed presented here demonstrates suitable accuracy to be used for advanced …

Gravity Wave Propagation Through A Vertically And Horizontally Inhomogeneous Background Wind, C. J. Heale, J. B. Snively

Publications

"A combination of ray theory and 2-D time-dependent simulations is used to investigate the linear effects of a time-dependent, vertically, and horizontally inhomogeneous background horizontal wind field on the propagation, refraction, and reflection of small-scale gravity wave packets. Interactions between propagating waves of different scales are likely to be numerous and important. We find that a static medium-scale wave wind field of sufficient amplitude can channel and/or critical-level filter a small-scale wave or cause significant reflection, depending upon both waves' parameters. However, the inclusion of a time-dependent phase progression of the medium-scale wave can reduce energy loss through critical-level filtering …

Hurricanes And Climate The U.S. Clivar Working Group On Hurricanes, Kevin J.E. Walsh, Suzana J. Camargo, Gabriel A. Vecchi, Anne Sophie Daloz, James Elsner, Kerry Emanuel, Michael Horn, Young-Kwon Lim, Malcom Roberts, Christina Patricola, Enrico Scoccimarro, Adam H. Sobel, Sarah Strazzo, Gabrielle Villarini, Michael Wehner, Ming Zhao, James P. Kossin, Tim Larow, Kazuyoshi Oouchi, Sigfried Schubert, Hui Wang, Julio Bacmeister, Ping Chang, Fabrice Chauvin, Christiane Jablonowski, Arun Kumar, Hiroyuki Murakami, Tomoaki Ose, Kevin A. Reed, Ramalingam Saravanan, Yohei Yamada, Colin M. Zarzycki, Pier Luigi Vidale, Jefferey A. Jonas, Naomi Henderson

Publications

While a quantitative climate theory of tropical cyclone formation remains elusive, considerable progress has been made recently in our ability to simulate tropical cyclone climatologies and to understand the relationship between climate and tropical cyclone formation. Climate models are now able to simulate a realistic rate of global tropical cyclone formation, although simulation of the Atlantic tropical cyclone climatology remains challenging unless horizontal resolutions finer than 50 km are employed. This article summarizes published research from the idealized experiments of the Hurricane Working Group of U.S. Climate and Ocean: Variability, Predictability and Change (CLIVAR). This work, combined with results from …

Lower Thermospheric Response To Atmospheric Gravity Waves Induced By The 2011 Tohoku Tsunami, Yonghui Yu, Zhiyu Yan, Michael P. Hickey Ph.D.

Publications

Previous GPS observations have revealed that while ionospheric TIDs were seen propagating in all directions away from the 2011 Tohoku earthquake epicenter, the total electron content (TEC) fluctuations associated with the subsequent tsunami were largest for waves propagating toward the northwest of the epicenter. Ionospheric motions observed approximately 10min after the earthquake were attributed to fast acoustic waves directly produced by the earthquake. Waves that first appeared about 40 min after the tsunami onset in TEC measurements were attributed to atmospheric gravity waves. In this paper, we conjecture that the remarkably different responses observed for the eastward and westward propagating …

Quantifying The Sensitivity Of Maximum, Limiting, And Potential Tropical Cyclone Intensity To Sst: Observations Versus The Fsu/ Coaps Global Climate Model, Sarah Strazzo, James Elsner, Tim Larow

Publications

No abstract provided.

Numerical Model Derived Altimeter Correction Maps For Non-Standard Atmospheric Temperature And Pressure, Thomas A. Guinn, Frederick R. Mosher

International Journal of Aviation, Aeronautics, and Aerospace

Altimeter corrections for non-standard temperature pose a challenge because accurate calculations require detailed knowledge of the temperature structure of the atmosphere between the surface and the aircraft. By applying basic hypsometric formulae to high resolution numerical model temperature and moisture output, detailed maps of current and forecasted corrected D-values are created. Corrected D-values provide the altitude difference between the true altitude and the indicated altitude from a pressure altimeter. Unlike standard D-values, the corrected D-value corrects for non-standard pressure in addition to non-standard temperature and is therefore useful for flights below class A airspace. Maps of corrected D-value may help …

A Full-Wave Model For A Binary Gas Thermosphere: Effects Of Thermal Conductivity And Viscosity, Michael P. Hickey Ph.D., R. L. Walterscheid, G. Schubert

Publications

The thermosphere is diffusively separated and behaves as a multiconstituent gas wherein individual species in static equilibrium are each stratified according to their individual scale heights. Gravity waves propagating in the thermosphere cause individual gases to oscillate with different amplitudes and phases. We use a two-gas (N2 and O) full-wave model to examine the roles of thermal conductivity, viscosity, and mutual diffusion on the wave-induced characteristics of both gases. In the lower thermosphere, where the gases are relatively tightly coupled, the major gas (N2) controls the minor gas (O) response. At higher altitudes, the gases become thermally and inertially decoupled, …

Efficient General Computational Method For Estimation Of Standard Atmosphere Parameters, Nihad E. Daidzic Ph.D., Sc.D.

International Journal of Aviation, Aeronautics, and Aerospace

Knowledge of standard air temperature, pressure, density, speed of sound, and viscosity as a function of altitude is essential information in aircraft design, performance testing, pressure altimeter calibration, and several other aeronautical engineering and aviation science applications. A new efficient computational method for rapid calculations of standard atmospheric parameters up to 86 orthometric km is presented. Additionally, mass and weight of each standard atmospheric layer were calculated using a numerical integration method. The sum of all fractional masses and weights represents the total mass and weight of Earth’s atmosphere. The results obtained here agree well with measurements and models of …

An Unusual Aerial Photograph Of An Eddy Circulation In Marine Stratocumulus Clouds (Picture Of The Month), Bradley M. Muller, Christopher G. Herbster, Frederick R. Mosher

Publications

An aerial photograph of a cyclonic, von Kármán–like vortex in the marine stratocumulus clouds off the California coast, taken by a commercial pilot near Grover Beach, is presented. It is believed that this is the first photograph of such an eddy, taken from an airplane, to appear in publication.

The eddy occurred with a strong inversion above a shallow marine boundary layer, in the lee of high, inversion-penetrating terrain. Tower and surface wind measurements plotted on satellite imagery demonstrate that the Grover Beach eddy was not just a cloud-level feature, but extended through the marine atmospheric boundary layer (MABL) to …

Improvement In Pilot Training For Aircraft Icing Conditions, Cody Denver, Melanie A. Wetzel

Aviation / Aeronautics / Aerospace International Research Conference

One of the most dangerous atmospheric hazards in aviation is aircraft icing. Ice can build on aircraft surfaces, causing decreases in thrust and lift while increasing drag and weight. These effects can be detrimental to any aircraft's ability to successfully remain in flight. Improvement in pilot knowledge of and response to icing conditions can be attained through use of specific meteorological forecast products, completion of interactive training modules, and understanding of cloud physical processes gained through the analysis of aircraft measurement case studies. This poster presents a strategy for enhancing the training of professional pilots in meteorological conditions which cause …

Use Of Research Aircraft Data To Validate Mesoscale Model Forecasts, Travis Swaggerty, Melanie Wetzel, Dorothea Ivanova

Aviation / Aeronautics / Aerospace International Research Conference

A NSF funded Student Training in Airborne Research and Technology (START) two-week deployment of the University of Wyoming King Air (UWKA) research aircraft was conducted at Embry-Riddle Aeronautical University (ERAU) in Prescott, Arizona during late March and early April 2014. Some of the goals of this program were to build knowledge on airborne atmospheric research for undergraduate students across multiple departments and to collect a valuable set of aircraft data for atmospheric model validation. Data collection for 10 research flights is available for mesoscale model case study validation.

This project utilizes the Weather Research and Forecasting mesoscale model (WRF), version …

Aviation Security Impacts Of Meteorological And Climatic Disruption, Melanie Wetzel

Aviation / Aeronautics / Aerospace International Research Conference

Commercial and military flight operations are frequently imperiled or disrupted by meteorological conditions. Severe weather events and climate-related factors create aviation security impacts on airport siting and reliability, human safety, economic stability, military defense strategy, aircraft routing and computer systems vulnerability. Climate trends have been associated with increased frequency of storm surge incursions at coastal airports, intense snowfall accumulations, runway closures due to rainstorm runoff, extended periods of fog/stratus restrictions and severe-weather related risk from lightning, hail and icing. The economic and safety impacts of these events are being incorporated into long-term planning by the U.S. Department of Defense (DoD), …

Wtic Research At Embry-Riddle Aeronautical University, Jessica Cruit, Beth Blickensderfer, John Lanicci, Bob Thomas, Thomas A. Guinn

Aviation Weather Training Research

No abstract provided.

Observational Evidence Of Quasi-27-Day Oscillation Propagating From The Lower Atmosphere To The Mesosphere Over 20° N, K.M. Huang, Alan Liu, S.D. Zhang, F. Yi, C.M. Huang

Publications

By using meteor radar, radiosonde and satellite observations over 20° N and NCEP/NCAR reanalysis data during 81 days from 22 December 2004 to 12 March 2005, a quasi-27-day oscillation propagating from the troposphere to the mesosphere is reported. A pronounced 27-day periodicity is observed in the raw zonal wind from meteor radar. Spectral analysis shows that the oscillation also occurs in the meridional wind and temperature and propagates westward with wavenumber s = 1; thus the oscillation is of Rossby wave type. The oscillation attains a large amplitude of about 12 m s−1 in the eastward wind shear region of …

A Swirl In The Clouds Near Santa Cruz Island (Images Of Note), Bradley M. Muller, Christopher G. Herbster

Publications

The authors discuss a rare photograph of an atmospheric eddy produced by marine boundary layer flow past terrain.

Editorial: Special Issue: Safety & Efficiency Of Civil Aviation: Selected Papers From The World Conferences Of The Air Transport Research Society And The World Conference On Transport Society - 2013, Paul Hooper, Ian Douglas, Chunyan Yu, Stefano Paleari

Publications

The Air Transport Research Society (ATRS) is a Special Interest Group (SIG) of the World Conference on Transport Research Society (WCTRS). The ATRS annual World Conference was held at the University of Bergamo, Bergamo, Italy on 26-29 June 2013 and it attracted 266 papers from 37 countries. Also, the WCTRS triennial World Conference was held on 15- 18 July at Rio de Janeiro, Brazil, during which the ATRS organised several sessions devoted to air transport topics. This special issue of the Journal of Air Transport Studies has drawn upon all of this material to present four papers that promote improvements …