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Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Atmospheric Sciences

Air Force Institute of Technology

2018

Articles 1 - 7 of 7

Full-Text Articles in Physical Sciences and Mathematics

A Statistical Analysis Of Steve, Bea Gallardo‐Lacourt, Y. Nishimura, E. Donovan, G. W. Gillies, W. E. Archer, Omar A. Nava, E. L. Spanswick Nov 2018

A Statistical Analysis Of Steve, Bea Gallardo‐Lacourt, Y. Nishimura, E. Donovan, G. W. Gillies, W. E. Archer, Omar A. Nava, E. L. Spanswick

Faculty Publications

There has been an exciting recent development in auroral research associated with the discovery of a new subauroral phenomenon called STEVE (Strong Thermal Emission Velocity Enhancement). Although STEVE has been documented by amateur night sky watchers for decades, it is as yet an unidentified upper atmosphere phenomenon. Observed first by amateur auroral photographers, STEVE appears as a narrow luminous structure across the night sky over thousands of kilometers in the east‐west direction. In this paper, we present the first statistical analysis of the properties of 28 STEVE events identified using Time History of Events and Macroscale Interactions during Substorms (THEMIS) …

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Estimation Of Atmospheric Turbulence Using Differential Motion Of Extended Features In Time-Lapse Imagery, Santasri Bose-Pillai, Jack E. Mccrae, Christopher A. Rice, Ryan A. Wood, Conner E. Murphy, Steven T. Fiorino Oct 2018

Estimation Of Atmospheric Turbulence Using Differential Motion Of Extended Features In Time-Lapse Imagery, Santasri Bose-Pillai, Jack E. Mccrae, Christopher A. Rice, Ryan A. Wood, Conner E. Murphy, Steven T. Fiorino

Faculty Publications

We address the design, development, and testing of a pointer/tracker as a probe beam for the purpose of making high-speed, aero-optical measurements of the flow over a scaled beam director turret. The tracker uses retro-reflection of the probe beam off of a Reflexite annulus surrounding the turret. The constraints of the design required a near-total-commercial off the shelf system that could be quickly installed and removed in a rented aircraft. Baseline measurements of environmental vibrations are used to predict pointing performance; mitigation of line-of-sight jitter on the probe beam is achieved through passive isolation and the design of relay optics. …

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A New Analysis Of The Gálvez-Davison Index For Convective Forecasts In Northern Africa, Gabriel D. Donndelinger Mar 2018

A New Analysis Of The Gálvez-Davison Index For Convective Forecasts In Northern Africa, Gabriel D. Donndelinger

Theses and Dissertations

Severe wind gusts and thunderstorms have been difficult to forecast in Africa. Traditional convective forecast tools (e.g. Total Totals Index, Lifted Index, K Index (KI) and Convective Available Potential Energy) do not accurately portray potential for thunderstorms in Africa. This research effort used the Gálvez-Davison Index (GDI), a convective index created for the tropics, and assess its applicability to northern Africa. GDI was produced for the Caribbean and Central America, and utilized temperature, moisture, mid-level stability, dry air entrainment and an elevation factor to calculate convective potential. In this research, GDI and KI were calculated using Global Forecast System (GFS) …

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The Geographic Distribution Of Downburst Frequency Across Spaceport Florida, Tania M. Garza Mar 2018

The Geographic Distribution Of Downburst Frequency Across Spaceport Florida, Tania M. Garza

Theses and Dissertations

Strong winds from downbursts pose a significant hazard to personnel and launch operations at Cape Canaveral Air Force Station (CCAFS) and NASA Kennedy Space Center (KSC). The CCAFS/KSC complex has a robust mesonet from which an 18 year (1995-2012) warm-season convective wind climatology (WSCWC) was developed (Koermer 2017). While the frequency of downbursts in the area has been determined, the frequency at the individual tower locations has not. The 5-minute peak wind data from the WSCWC was analyzed to determine the geographic distribution of downburst frequency across Spaceport Florida. For this project a downburst was determined by the threshold of …

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Impacts Of Sub-Auroral Polarization Streams On High Frequency Operations As A Function Of Modeled Particle Energy Flux, Nathan D. Smith Mar 2018

Impacts Of Sub-Auroral Polarization Streams On High Frequency Operations As A Function Of Modeled Particle Energy Flux, Nathan D. Smith

Theses and Dissertations

Space weather events can cause irregularities within the ionosphere; in particular, this research examines sub-auroral polarization streams (SAPS), as their accompanying irregularities and effects can degrade high-frequency (HF) signal propagation. It is known that the strongest westerly current drifts delineating SAPS are associated with a deep ionospheric trough, which in turn contaminates HF data with clutter from the non-standard ionosphere. Having a methodology to track and identify these occurrences on current computational architecture would provide operators enhanced situational awareness in knowing to expect degradation in HF processes. This study has discovered a weak, yet significant, exponentially decaying correlation between maximum …

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Evaluation Of A Cloud Detection Technique Using Spatial And Radiometric Thresholds For Near Infrared Satellite Imagery, William J. Graff Mar 2018

Evaluation Of A Cloud Detection Technique Using Spatial And Radiometric Thresholds For Near Infrared Satellite Imagery, William J. Graff

Theses and Dissertations

Knowledge of cloud location in near infrared (NIR) imagery is of interest to the meteorological community given the wavelengths greater spatial resolution compared to longwave infrared and its potential nighttime applications. This method consists of an algorithm that can be employed by multiple instrument platforms. It analyzes changes between satellite image radiances and a seasonal synthetic background radiance image. The NIR sensor bands of the Sentinel-2 Multispectral Instrument (MSI) and Suomi National Polar-Orbiting Partnership (Suomi NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) satellite instruments are used to evaluate the performance of a monochromatic change detection technique designed to locate areas …

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Forecasting Lightning Initiation Utilizing Dual-Polarization Radar Parameters Over Washington, D.C., Sarah A. Olsen Mar 2018

Forecasting Lightning Initiation Utilizing Dual-Polarization Radar Parameters Over Washington, D.C., Sarah A. Olsen

Theses and Dissertations

Accurate forecasts of thunderstorms are vital to space launch, aviation, and public safety. Prior studies by Woodard (2011), Thurmond (2014), and Travis (2015) show that dual-polarization radar can be utilized to identify the presence of hydrometeors necessary for cloud charging. These studies emphasized that a combination of radar reflectivity (Z) and differential reflectivity (ZDR) predictors have the potential to improve forecast skill of lightning initiation over methods that rely on Z alone (Roeder and Pinder, 1998; Yang and King, 2010). Travis (2015) discovered two parameters, when used together, produced the best results: Z ≥ 36.5 dBZ and ZDR …

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