Atmospheric Sciences Commons^™

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 …

Investigation Of Mountain Waves In The Mesosphere Over The Andes Mountains, Jaime Aguilar Guerrero

Doctoral Dissertations and Master's Theses

An image processing algorithm has been developed to analyze data from a NIR All-Sky Imager of OH airglow emission (from about 87 km altitude), located in the Andes, with the purpose of investigating the atmospheric gravity waves generated when low level wind blows over the high mountains (referred to as Mountain Waves). These types of waves are a special case of atmospheric gravity waves, which carry significant momentum and exert strong forcing to the background upper atmosphere. The imager is located at the Andes Lidar Observatory (ALO) at Cerro Pachón, Chile (30°S, 71°W), which also houses a Na Doppler Lidar …

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, …

Comparing Different Methods For Estimating Total Open Heliospheric Magnetic Flux, Samantha J. Wallace

Doctoral Dissertations and Master's Theses

There are extended periods over the solar cycle where significant discrepancies occur between the observed open magnetic flux (i.e., those based on spacecraft observations) and that determined from coronal models. One explanation for the source of these discrepancies is the magnetic fields in CMEs, which have yet to magnetically disconnect from the Sun. These “closed” flux sources can be included in open flux estimates, because open and closed magnetic field lines are not easily distinguished in spacecraft data. Another possibility is that a portion of the open flux measured by in situ spacecraft originates from the time-dependent evolution of solar …

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 …

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 …

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 …

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.

Langmuir Probe Instrument Suite For Mesosphere Turbulence Experiment Mission, Adam Blake

Doctoral Dissertations and Master's Theses

The Langmuir probe technique is the predominant in-situ plasma diagnostic technique, and is arguably the only measurement technique that is universally own on every sounding rocket investigation. Earth's mesosphere region (80-120 km) is a host of many dynamic phenomena such as the noctilucent clouds, breaking gravity waves, inversion layers, settlement of mesospheric smoke particles, etc. As such it is critical to have a comprehensive suite of plasma diagnostics that can unambiguously measure various plasma parameters.

This thesis deals with the development and testing of three different Langmuir probe implementations suitable for investigation of the mesosphere which are to be launched …

Challenges Associated With Space Weather Analysis And Prediction, John Lanicci

Space Traffic Management Conference

The term “space weather” is typically used to describe environmental conditions in the region extending from the sun’s surface, through the interplanetary medium, to the earth’s magnetic field and upper atmosphere, with a focus on those conditions that can affect the earth, its technological systems, and population. Space weather conditions are monitored continuously by a number of agencies around the world. These agencies use both satellite- and ground-based measurements to build analyses and employ predictive models that form the basis for impacts-based products dealing with myriad users in satellite operations, the utility industry, aviation, and satellite-based communications, to name a …

Incoherent Scatter Radar Observations Of Dynamic Ion Composition Changes At High Latitudes During Geomagnetic Storms, Bryan C. Wright

Doctoral Dissertations and Master's Theses

Two new methods are developed for estimating F region ion composition from field-aligned incoherent scatter radar (ISR) measurements. These methods address incoherent scatter spectra temperature-mass ambiguities by self-consistently modeling ion temperature profiles as a function of electric fields and plasma interactions with the neutral atmosphere. These two new methods improve on previous, similar work developed in Zettergren et al. [2010,2011] by incorporating more accurate physical models and improving the estimation procedures. These techniques enable studies of ionospheric composition during highly disturbed conditions and are suitable for data collected with short integration times (2-10 minutes). The improved models incorporate the effects …

Numerical Simulation Of The Long-Range Propagation Of Gravity Wave Packets At High Latitudes, C. J. Heale, J. B. Snively, M. P. Hickey

Publications

We use a 2-D, nonlinear, time-dependent numerical model to simulate the propagation of wave packets under average high latitude, winter conditions. We investigate the ability of waves to propagate large horizontal distances, depending on their direction of propagation relative to the average modeled ambient winds. Wave sources were specified to represent the following: (1) the most common wave parameters inferred from observations of Nielsen et al. (2009) ((18 km λᵪ , 7.5 min period), (2) waves consistent with the average phase speed observed (40 m/s) but outlying horizontal wavelength and period values (40 km λᵪ , 17 min period), and …

Ion-Cyclotron Resonance Heating Of O+ In The Topside Ionosphere And Mapping Outflows To The Magnetosphere, Anthony W. Pritchard

Doctoral Dissertations and Master's Theses

This thesis considers the heavy ion dynamics due to ion-cyclotron resonance energization processes that take place in the turbulent region of the Earth’s topside, high latitude ionosphere. We simulate the impact of this transverse heating process upon energies and velocity distribution functions of outflowing oxygen ions (O+) in the approximate altitude range of 800 km to 15,000 km. To do so most effectively, we use a single particle tracing model that precisely reproduces the small-scale wave-particle interaction of broadband extremely low frequency (BBELF) waves with the ions’ cyclotron motions, leading to the upward acceleration of ions in type-II ion outflows …

Aerodynamic Study Of Forces Due To Wind Velocity And Angle Of Attack On Parabolic Solar Troughs, Brian Northshield

Doctoral Dissertations and Master's Theses

Scant literature exists of the atmospheric effects on parabolic solar troughs. The technology is relatively new, so supporting studies by consequence are as well.

This study examines the effects of wind at various speeds, with various angles of attack on parabolic solar troughs. This begins by picking up on previous study, corroborating previously found data, then introduces new angles of attack. The model includes the presence of the solar tube where other studies omit.

The purpose of this study is to build a data set which is useful for structural consideration. During the course of this study, it was found …

Thermospheric Dissipation Of Upward Propagating Gravity Wave Packets, C. J. Heale, J. B. Snively, M. P. Hickey, C. J. Ali

Publications

We use a nonlinear, fully compressible, two-dimensional numerical model to study the effects of dissipation on gravity wave packet spectra in the thermosphere. Numerical simulations are performed to excite gravity wave packets using either a time-dependent vertical body forcing at the bottom boundary or a specified initial wave perturbation. Three simulation case studies are performed to excite (1) a steady state monochromatic wave, (2) a spectrally broad wave packet, and (3) a quasi-monochromatic wave packet. In addition, we analyze (4) an initial condition simulation with an isothermal background. We find that, in cases where the wave is not continually forced, …

Very Low Frequency Subionospheric Remote Sensing Of Thunderstorm-Driven Acoustic Waves In The Lower Ionosphere, R. A. Marshall, J. B. Snively

Publications

"We present observations of narrowband subionospheric VLF transmitter signals on 20 March 2001, exhibiting coherent fluctuations of over 1 dB peak to peak. Spectral analysis shows that the fluctuations have periods of 1–4 min and are largely coherent. The subionospheric propagation path of the signal from Puerto Rico to Colorado passes over two regions of convective and lightning activity, as observed by GOES satellite imagery and National Lightning Detection Network lightning data. We suggest that these fluctuations are evidence of acoustic waves launched by the convective activity below, observed in the 80–90 km altitude range to which nighttime VLF subionospheric …

Auroral Ionospheric F Region Density Cavity Formation And Evolution: Mica Campaign Results, M. Zettergren, K. A. Lynch, D. L. Hampton, M. Nicolls, B. Wright, Et Al.

Publications

Auroral ionospheric F region density depletions observed by PFISR (Poker Flat Incoherent Scatter Radar) during the MICA (Magnetosphere‐Ionosphere Coupling in the Alfvén Resonator) sounding rocket campaign are critically examined alongside complementary numerical simulations. Particular processes of interest include cavity formation due to intense frictional heating and Pedersen drifts, evolution in the presence of structured precipitation, and refilling due to impact ionization and downflows. Our analysis uses an ionospheric fluid model which solves conservation of mass, momentum, and energy equations for all major ionospheric species. These fluid equations are coupled to an electrostatic current continuity equation to self‐consistently describe auroral electric …

Aircraft Icing Potential And Ice- And Mixed-Phase Cloud Microphysics, Victoria A. Walker, Dorothea Ivanova

Aviation / Aeronautics / Aerospace International Research Conference

Abstract
Cold cloud interactions with aircrafts that fly through them require knowledge of cloud microphysics. Aircrafts must be designed to fly into supercooled clouds, or they must avoid those clouds in order to prevent problems associated with airframe and engine icing. De-icing or anti-icing systems must be engineered to withstand reasonable extremes in terms of ice water content (IWC), supercooled liquid water content (LWC), ice particle size distributions (SDs), and temperature. The aircraft design or certification envelopes (FAR 25, Appendix C; Federal Aviation Administration, 1999) were developed before the advent of modern cloud physics instrumentation. In the case of ice …

Campus-Based Training In Airborne Atmospheric Research, Melanie Wetzel, Dorothea Ivanova

Aviation / Aeronautics / Aerospace International Research Conference

Embry-Riddle Aeronautical University (ERAU) campus in Prescott, Arizona will conduct an aircraft measurement program during Spring Semester 2014 to introduce students in meteorology, aeronautical sciences and other departments to airborne scientific research technology and research flight logistics. The ERAU Department of Meteorology has support from the National Science Foundation (NSF) Division of Atmospheric and Geospace Sciences for an educational deployment of the University of Wyoming King Air (UWKA).

Long-Range Propagation, Interaction, And Dissipation Of Small-Scale Gravity Waves In The Mesosphere And Lower Thermosphere, Christopher J. Heale

Doctoral Dissertations and Master's Theses

A 2-D nonlinear, compressible numerical model [Snively and Pasko, 2008] is used in conjunction with ray-theory to investigate the long-range propagation, dissipation and interaction of small-scale gravity waves in the Mesosphere and Lower Thermosphere (MLT) region. The research in this thesis is made up of three distinct studies which build upon each other. The first investigates the thermospheric dissipation of three gravity wave packets representing: (1) A quasi-monochromatic packet, (2) A monochromatic, steady state wave, and (3) A spectrally broad packet, as well as an initial condition specified packet. It is found that dissipation due to molecular viscosity and …

Adjusted Tornado Probabilities, Holly M. Widen, James B. Elsner, Cameron Amrine, Rizalino B. Cruz, Erik Fraza, Laura Michaels, Loury Migliorelli, Brendan Mulholland, Michael Patterson, Sarah Strazzo, Guang Xing

Publications

Tornado occurrence rates computed from the available reports are biased low relative to the unknown true rates. To correct for this low bias, the authors demonstrate a method to estimate the annual probability of being struck by a tornado that uses the average report density estimated as a function of distance from nearest city/town center. The method is demonstrated on Kansas and then applied to 15 other tornado-prone states from Nebraska to Tennessee. States are ranked according to their adjusted tornado rate and comparisons are made with raw rates published elsewhere. The adjusted rates, expressed as return periods, arestates, including …

Wave Heating And Jeans Escape In The Martian Upper Atmosphere, R. L. Walterscheid, Michael P. Hickey Ph.D., G. Schubert

Publications

Gusty flow over rough terrain is likely to be a significant source of fast gravity waves and acoustic waves in the atmosphere of Mars, as it is in Earth’s atmosphere. Accordingly, we have used a numerical model to study the dissipation in the thermosphere and exosphere of Mars of upward-propagating fast gravity waves and acoustic waves. Model simulations are performed for a range of wave periods and horizontal wavelengths. Wave amplitudes are constrained by the Mars Global Surveyor and Mars Odyssey aerobraking data, and gravity wave phase velocities are limited by occultation data. Dissipating gravity waves heat some regions of …

Mapping Of The Quasi-Periodic Oscillations At The Flank Magnetopause Into The Ionosphere, Emily R. Dougal

Doctoral Dissertations and Master's Theses

We have estimated the ionospheric location, area, and travel time of quasi-periodic oscillations originating from the magnetospheric flanks. This was accomplished by utilizing global and local MHD models and Tsyganenko semi-empirical magnetic field model on multiple published and four new cases believed to be caused by the Kelvin-Helmholtz Instability. Finally, we used auroral, magnetometer, and radar instruments to observe the ionospheric signatures. The ionospheric magnetic latitude determined using global MHD and Tsyganenko models ranged from 58.3-80.2 degrees in the northern hemisphere and -59.6 degrees to -83.4 degrees in the southern hemisphere. The ionospheric magnetic local time ranged between 5.0-13.8 hours …

Observed Versus Gcm-Generated Local Tropical Cyclone Frequency: Comparisons Using A Spatial Lattice, Sarah Strazzo, Daniel J. Halperin, James Elsner, Tim Larow, Ming Zhao

Publications

Of broad scientific and public interest is the reliability of global climate models (GCMs) to simulate future regional and local tropical cyclone (TC) occurrences. Atmospheric GCMs are now able to generate vortices resembling actual TCs, but questions remain about their fidelity to observed TCs. Here the authors demonstrate a spatial lattice approach for comparing actual with simulated TC occurrences regionally using observed TCs from the International Best Track Archive for Climate Stewardship (IBTrACS) dataset and GCM-generated TCs from the Geophysical Fluid Dynamics Laboratory (GFDL) High Resolution Atmospheric Model (HiRAM) and Florida State University (FSU) Center for Ocean–Atmospheric Prediction Studies (COAPS) …

Auroral Ion Upflows: Sources, High Altitude Dynamics, And Neutral Wind Effects, Meghan R. Burleigh

Doctoral Dissertations and Master's Theses

Large upwellings of thermal plasma are commonly observed in the high-latitude, topside ionosphere. These auroral ion upflows have a range of potential sources including frictional heating, electron precipitation, neutral winds, and higher-altitude density cavities. The unique signatures and detailed evolution of these upflows are examined through the use of Incoherent Scatter Radar data and a sophisticated ionospheric fluid model.

A survey of solar cycle 23 shows that at Sondrestrom upflows occur most often in the cusp region and midnight auroral zone. Simplified force balance analysis and steady state velocity calculations are applied to a few select events to elucidate the …