Atmospheric Sciences Commons^™

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 …

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 …

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 …

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 …

Numerical Analysis And Theory Of Oblique Alfvenic Solitons Observed In The Interplanetary Magnetic Field, Harry Raphael Wheeler Iv

Doctoral Dissertations and Master's Theses

Recently, there have been reports of small magnetic pulses or bumps in the interplanetary magnetic field observed by various spacecraft. Most of these reports claim that these localized pulses or bumps are solitons. Solitons are weakly nonlinear localized waves that tend to retain their form as they propagate and can be observed in various media which exhibit nonlinear steepening and dispersive effects. This thesis expands the claim that these pulses or bumps are nonlinear oblique Alfven waves with soliton components, through the application of analytical techniques used in the inverse scattering transform in a numerical context and numerical integration of …

Identification And Classification Of Stratospheric Sudden Warming Events, Thomas S. Ehrmann

Doctoral Dissertations and Master's Theses

Analysis of northern hemisphere stratospheric data from 1978-2011 is used to identify and classify Stratospheric Sudden Warming events. A total of 41 events are identified during this 33 year period, resulting in an average occurrence rate of 1.24 events/year. No significant variation in the rate is observed during the period analyzed. The average temperature increase during an SSW event is 12 K and the average duration is 32 days. Each identified event is classified as either a vortex displacement or split event and the ratio of displacement to split events is found to be 0.86.

Identifying Signatures Of Plasma Waves And Reconnection Associated With Kelvin-Helmholtz Activity, Thomas Wesley Moore

Doctoral Dissertations and Master's Theses

The magnetopause marks the boundary between the shocked solar wind and magnetospheric plasma. Understanding the dynamics of the plasma processes at the magnetopause boundary is crucial to the study of plasma transport into the magnetosphere. Previous studies have shown that there exists a temperature asymmetry in the plasma sheet. During northward IMF, the cold component ions are 30-40% hotter in the dawn flank plasma sheet compared to the dusk flank. However, the mechanisms responsible are still not entirely clear. Recent work has shown that reconnection in Kelvin-Helmholtz vortices can transport plasma into the magnetosphere. Previous studies have also shown that …

On The Variation Of Gravity Wave Activity Through The Solar Cycle At The South Pole, Ryan Matthew Agner

Doctoral Dissertations and Master's Theses

Atmospheric dynamics comprise of a multitude of phenomena from various sources that affect the entire climate of the globe. Some of these phenomena include Atmospheric Gravity Waves which are ubiquitous features around the planet. They are important mechanisms for the transport of momentum and energy from the lower atmosphere to the upper atmosphere. The sun is the ultimate source of energy for the earth and the primary driver of atmospheric dynamics. The 11-year solar cycle of the sun has had a noticeable effect on the overall climate of the earth in the past. More recent work has seen the diurnal …

Fabry-Perot Observations Of Midlatitude Neutral Winds And Atmospheric Gravity Wave Activity, Marjory Anne Katon

Doctoral Dissertations and Master's Theses

The mesosphere and lower thermosphere displays a wide range of dynamical phenomena resulting in a complex and variable regions. Governed primarily by fluid dynamics, the motion of the upper atmosphere is modulated by a number of atmospheric waves propagating upward from various sources in the lower atmosphere. Among these are atmospheric gravity waves which have been recognized as a major source of momentum and energy in the mesosphere and lower thermosphere as well as a major factor in the dynamic coupling between the troposphere and lower thermosphere. A Fabry-Perot interferometer possessed by the Space Physics Research Laboratory at the Embry-Riddle …