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Full-Text Articles in Physics

Intra-Annual Comparison Of Mesospheric Gravity Waves Over Halley And Rothera Stations, Antarctica, Jonathan Pugmire, Michael J. Taylor, K. Nielsen, A. Wall, J. Thompson, P. D. Pautet Oct 2009

Intra-Annual Comparison Of Mesospheric Gravity Waves Over Halley And Rothera Stations, Antarctica, Jonathan Pugmire, Michael J. Taylor, K. Nielsen, A. Wall, J. Thompson, P. D. Pautet

Graduate Student Posters

No abstract provided.


Intra-Annual Comparison Of Mesospheric Gravity Waves Over Halley And Rothera Stations, Antarctica., Jonathan R. Pugmire, Mike J. Taylor, Kim Nielsen May 2009

Intra-Annual Comparison Of Mesospheric Gravity Waves Over Halley And Rothera Stations, Antarctica., Jonathan R. Pugmire, Mike J. Taylor, Kim Nielsen

Jonathan Pugmire

As part of a collaborative program between British Antarctic Survey and Utah State University, we present an intra-annual study of short-period, mesospheric gravity wave events observed over Antarctica in the near infrared OH emission. The measurements were made using an all-sky airglow imager operated at either Halley Station on the Brunt Ice Shelf, or Rothera Station, situated on the Antarctic Peninsula. A total of six austral winter seasons have been analyzed (2000-2006). This study comprises the first detailed winter seasonal investigation of short-period mesospheric gravity waves at high-Antarctic latitudes. Distributions of their observed wave parameters were found to be similar …


Rayleigh-Lidar Observations Of Mesospheric Instabilities, Gabriel C. Taylor, Durga N. Kafle, Vincent B. Wickwar Apr 2009

Rayleigh-Lidar Observations Of Mesospheric Instabilities, Gabriel C. Taylor, Durga N. Kafle, Vincent B. Wickwar

Posters

From 1993 to 2004 the Utah State University Rayleigh lidar, known as the USU green laser, collected 900 nights of data from the mesosphere (45-90 km). From these observations profiles of relative neutral densities and absolute temperatures were derived. Usually, the atmosphere is horizontally stratified with a balance between gravitational and pressure forces. When this balance is perturbed, it leads to the generation of buoyancy or “gravity” waves. An example of these is clear air turbulence, which can have dramatic effects on airplanes. As these waves propagate upward, the decrease in atmospheric density and conservation of energy combine to give …


A Computational Tool For Evaluating Thz Imaging Performance In Brownout Conditions At Land Sites Throughout The World, Seth L. Marek Mar 2009

A Computational Tool For Evaluating Thz Imaging Performance In Brownout Conditions At Land Sites Throughout The World, Seth L. Marek

Theses and Dissertations

This study quantifies terahertz (THz) or sub-millimeter imaging performance during simulated rotary-wing brownout or whiteout environments based on geographic location and recent/current atmospheric weather conditions. The atmospheric conditions are defined through the Air Force Institute of Technology Center for Directed Energy (AFIT/CDE) Laser Environmental Effects Definition and Reference or LEEDR model. This model enables the creation of vertical profiles of temperature, pressure, water vapor content, optical turbulence, and atmospheric particulates and hydrometeors as they relate to line-by-line layer extinction coefficient magnitude at wavelengths from the UV to the RF. Optical properties and realistic particle size distributions for the brownout and …


Demonstration And Verification Of A Broad Spectrum Anomalous Dispersion Effects Tool For Index Of Refraction And Optical Turbulence Calculations, J. Jean Cohen Mar 2009

Demonstration And Verification Of A Broad Spectrum Anomalous Dispersion Effects Tool For Index Of Refraction And Optical Turbulence Calculations, J. Jean Cohen

Theses and Dissertations

An atmospheric optical turbulence strength model with a broad wavelength range of 355nm (ultraviolet) to 8.6m (radio frequencies) has been created at AFIT and implemented into the High Energy Laser End-to-End Operational Simulation tool (HELEEOS). This modeling and simulation tool is a first principles atmospheric propagation and characterization model. Within HELEEOS lies the High-Resolution Transmission Molecular Absorption (HITRAN) database, containing 1,734,469 spectral lines for 37 different molecules as of version 12.0 (2004). HITRAN affords HELEEOS incredible accuracy for electromagnetic (EM) propagation prediction. A full understanding of optical turbulence is needed to successfully predict EM radiation propagation, particularly within the application …


Assessment Of Weather Sensitivities And Air Force Weather (Afw) Support To Tactical Lasers In The Lower Troposphere, Francesco J. Echeverria Mar 2009

Assessment Of Weather Sensitivities And Air Force Weather (Afw) Support To Tactical Lasers In The Lower Troposphere, Francesco J. Echeverria

Theses and Dissertations

ATL scientists need to develop a full understanding of the interaction effects between a high-energy laser beam and the atmosphere through which it propagates. Achieving this understanding is important for many reasons. In particular, the high cost of DE weapons systems makes each propagation event expensive. Having an understanding of the atmosphere in which a high-energy laser propagates will increase efficiency and effectiveness of the ATL weapon system, which in turn will decrease cost of operation. A tool that allows for the ATL war-fighter to determine the atmospheric effects on laser propagation currently does not exist. This study creates a …


Multilayered Structures In The Ionosphere F2 Region And Impulse-Like Increase Of The Nightglow Red 630 Nm Line Intensity As A Result Of Influence Of Shear Excited Atmospheric Vortical Perturbations, G. G. Didebulidze, Levan Lomidze, N. B. Gudadze, M. Todua Dec 2008

Multilayered Structures In The Ionosphere F2 Region And Impulse-Like Increase Of The Nightglow Red 630 Nm Line Intensity As A Result Of Influence Of Shear Excited Atmospheric Vortical Perturbations, G. G. Didebulidze, Levan Lomidze, N. B. Gudadze, M. Todua

Levan Lomidze

It is shown that the formation of multilayered structures in the midlatitude ionosphere F 2 layer can be caused by atmospheric vortical perturbation (shear wave) evolving in the meridional wind with linear zonal shear and can be accompanied by an impulse-like increase (with duration about 1–3 h) in the red 630 nm line total nightglow intensity. The shear wave can produce an enhancement of the northward wind (or decrease in the southward one), which can cause a downward motion of the F 2 layer peak height resulting in the impulse-like increase in the red line intensity. An important increase in …