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

Oceanography and Atmospheric Sciences and Meteorology Commons™

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

Air Force Institute of Technology

Discipline
Keyword
Publication Year
Publication
Publication Type

Articles 61 - 90 of 283

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

Comparison Of Seasonal Foes And Fbes Occurrence Rates Derived From Global Digisonde Measurements, Dawn K. Merriman, Omar A. Nava, Eugene V. Dao, Daniel J. Emmons Ii Dec 2021

Comparison Of Seasonal Foes And Fbes Occurrence Rates Derived From Global Digisonde Measurements, Dawn K. Merriman, Omar A. Nava, Eugene V. Dao, Daniel J. Emmons Ii

Faculty Publications

A global climatology of sporadic-E occurrence rates (ORs) based on ionosonde measurements is presented for the peak blanketing frequency, fbEs, and the ordinary mode peak frequency of the layer, foEs. ORs are calculated for a variety of sporadic-E frequency thresholds: no lower limit, 3, 5, and 7 MHz. Seasonal rates are calculated from 64 Digisonde sites during the period 2006–2020 using ionograms either manually or automatically scaled with ARTIST-5. Both foEs and fbEs ORs peak in the Northern Hemisphere during the boreal summer, with a decrease by roughly a factor of 2–3 in fbEs rates relative to foEs rates without …

Go to article

Ionospheric F-Layer Dipole Flute Instability Effects On Electromagnetic Scattering In A Magnetohydrodynamic Plasma, Andrew J. Knisely Nov 2021

Ionospheric F-Layer Dipole Flute Instability Effects On Electromagnetic Scattering In A Magnetohydrodynamic Plasma, Andrew J. Knisely

Theses and Dissertations

The ionosphere has significant impact on radio frequency (RF) applications such as satellites, over-the-horizon radar, and commercial communication systems. The dynamic processes effecting the behavior of the ionic content leads to a variety of instabilities that adversely affect the quality of RF signals. In the F-layer ionosphere, flute instability persists, appearing as two radial regions of high and low density perturbations elongated along the earth's geomagnetic field lines. The sizes of flute structures are comparable to the wavelengths in the high frequency spectrum. The objective is to characterize the high frequency scattering of an incident field by developing a 3D …

Go to article

Development And Verification Of Extreme Space Weather Phenomena Models, Sophia G. Schwalbe Sep 2021

Development And Verification Of Extreme Space Weather Phenomena Models, Sophia G. Schwalbe

Theses and Dissertations

A range of 14 M-class flares from 1 June 2015 to 27 September 2016 were analyzed to find significant trends in electron frequency profile modeling using the GLobal airglOW (GLOW) model and radar parameters using a ray tracing algorithm developed by the Air Force Research Laboratory. GLOW was run for all the flares using three different solar spectrum schemes and an average of the three: the Hinteregger method, EUV flux model for aeronomic calculations (EUVAC), and a rebinned Flare Irradiance Spectrum Model (FISM) result. Comparing data for the E-layer where GLOW is most accurate, it was determined that GLOW using …

Go to article

Deep Learning For Weather Clustering And Forecasting, Nathaniel R. Beveridge Sep 2021

Deep Learning For Weather Clustering And Forecasting, Nathaniel R. Beveridge

Theses and Dissertations

Clustering weather data is a valuable endeavor in multiple respects. The results can be used in various ways within a larger weather prediction framework or could simply serve as an analytical tool for characterizing climatic differences of a particular region of interest. This research proposes a methodology for clustering geographic locations based on the similarity in shape of their temperature time series over a long time horizon of approximately 11 months. To this end an emerging and powerful class of clustering techniques that leverages deep learning, called deep representation clustering (DRC), are utilized. Moreover, a time series specific DRC algorithm …

Go to article

Profiling Atmospheric Turbulence Using A Dynamically Ranged Rayleigh Beacon System, Steven M. Zuraski Sep 2021

Profiling Atmospheric Turbulence Using A Dynamically Ranged Rayleigh Beacon System, Steven M. Zuraski

Theses and Dissertations

The effect of turbulence on a long range imaging system manifest as an image blur effect usually quantified by the phase distortions present in a system. The blurring effect is conceivably understood on the basis of measured strength of atmospheric turbulence profiled within the propagation volume. One method for obtaining a turbulence strength profile is by use of a dynamically ranged Rayleigh beacon system that exploits strategically varied beacon ranges along the propagation path, effectively deducing estimates of specific path segment contributions of the blurring aberrations affecting an optical imaging system. A system utilizing this technique has been designed, and …

Go to article

Relationship Between Solar Energetic Particle He/H Abundance Ratios And Properties Of Flares And Cmes, Christopher R. Davidson Sep 2021

Relationship Between Solar Energetic Particle He/H Abundance Ratios And Properties Of Flares And Cmes, Christopher R. Davidson

Theses and Dissertations

Previous studies have investigated the He/H elemental abundance ratios of Solar Energetic Particle (SEP) Events of energies above 4 MeV. Also, studies have investigated the correlations between SEPs, Coronal Mass Ejections (CME), and Solar Flares. This work finds the correlations between the >4 MeV He/H abundance ratios and the solar parameters from the SEP, CME, and solar flare associated with the abundance increases. 43 SEP events located at solar west longitude are analyzed to find the correlation coefficients. Highly significant correlation was found between the He/H abundance ratios and the following parameters: solar flare flux, solar flare fluence, CME linear …

Go to article

Large Eddy Simulations Of Turbulent And Buoyant Flows In Urban And Complex Terrain Areas Using The Aeolus Model, Akshay A. Gowardhan, Dana L. Mcgufffin, Donald L. Lucas, Stephanie J. Neuscamman, Otto Alvarez, Lee G. Glascoe Aug 2021

Large Eddy Simulations Of Turbulent And Buoyant Flows In Urban And Complex Terrain Areas Using The Aeolus Model, Akshay A. Gowardhan, Dana L. Mcgufffin, Donald L. Lucas, Stephanie J. Neuscamman, Otto Alvarez, Lee G. Glascoe

Student Publications

Fast and accurate predictions of the flow and transport of materials in urban and complex terrain areas are challenging because of the heterogeneity of buildings and land features of different shapes and sizes connected by canyons and channels, which results in complex patterns of turbulence that can enhance material concentrations in certain regions. To address this challenge, we have developed an efficient three-dimensional computational fluid dynamics (CFD) code called Aeolus that is based on first principles for predicting transport and dispersion of materials in complex terrain and urban areas. The model can be run in a very efficient Reynolds average …

Go to article

Impact Of Hurricane Michael (2018) On Local Vertical Total Electron Content, Joanna E.S. Williams, Robert C. Tournay, H. Rose Tseng, Daniel J. Emmons Ii, Omar A. Nava Apr 2021

Impact Of Hurricane Michael (2018) On Local Vertical Total Electron Content, Joanna E.S. Williams, Robert C. Tournay, H. Rose Tseng, Daniel J. Emmons Ii, Omar A. Nava

Faculty Publications

An analysis of vertical total electron content (TEC) estimates from the MIT Madrigal database is performed for the regions surrounding the eye of Hurricane Michael (2018). Absolute and detrended TEC values show a noticeable increase during the tropical cyclone (TC) relative to fluctuations at the same locations prior to the storm. Direct comparisons of TEC perturbation magnitudes to the number of lightning flashes in latitude-longitude boxes surrounding the eye of Hurricane Michael for each 5 min period of 10 October 2018 showed no visible trends. A similar comparison of the vertical TEC fluctuations with respect to the rainfall rates showed …

Go to article

Synthetic Lightning Generation Employing Autoregressive-Moving-Average (Arma) Models, Seth R. Powers Mar 2021

Synthetic Lightning Generation Employing Autoregressive-Moving-Average (Arma) Models, Seth R. Powers

Theses and Dissertations

This work explores the question as to whether lightning data can be generated synthetically using vector autoregressive-moving-average (VARMA) models. Geostationary Lightning Mapper (GLM) data is used as the basis for the study. Lightning climatology is examined and compared to previous research to gain insight into the targeted areas. Individual lightning ashes are analyzed to inspect how well the process works on a smaller scale. Then, entire regions are evaluated to simulate lightning creation in a larger setting. Results suggest that the VARMA process employed is sufficient in generating synthetic lightning observations, largely dependent on the time and location of lightning …

Go to article

Climate-Informed Prediction And Forecast Modeling Of Installation Total Energy Consumption, Scott C. Weiss Mar 2021

Climate-Informed Prediction And Forecast Modeling Of Installation Total Energy Consumption, Scott C. Weiss

Theses and Dissertations

Climate variability is an external and stochastic factor that causes energy demand uncertainty. Energy managers can use climate-based models to understand future trends of energy demand and to adjust operations, policy, and budgets accordingly. This research focuses on 1) identifying how climate attributes impact energy use, 2) creating a historically informed statistical modeling framework to skillfully predict energy use, and 3) forecasting future changes to energy use and costs, using CMIP5 temperature projections, at the campus level. After synthesizing the existing breadth of research on climate-informed energy modeling, a skillful, unbiased, climate-informed total energy consumption prediction model is developed for …

Go to article

Correction Of Back Trajectories Utilizing Machine Learning, Britta F. Gjermo Morrison Mar 2021

Correction Of Back Trajectories Utilizing Machine Learning, Britta F. Gjermo Morrison

Theses and Dissertations

The goal of this work was to analyze 24-hour back trajectory performance from a global, low-resolution weather model compared to a high-resolution limited area weather model in particular meteorological regimes, or flow patterns using K-means clustering, an unsupervised machine learning technique. The duration of this study was from 2015-2019 for the contiguous United States (CONUS). Three different machine learning algorithms were tested to study the utility of these methods improving the performance of the CFS relative to the performance of the RAP. The aforementioned machine learning techniques are linear regression, Bayesian ridge regression, and random forest regression. These results mean …

Go to article

Improving Airfield Pavement Degradation Prediction Skill With Local Climate And Traffic, Evan M. Fortney Mar 2021

Improving Airfield Pavement Degradation Prediction Skill With Local Climate And Traffic, Evan M. Fortney

Theses and Dissertations

Airfield pavements are a critical component of the global transportation network that provide a platform for national defense. Preventative and corrective maintenance activities are founded upon accurate expectations of degradation. The leading pavement management software creates degradation predictions from pavement groups using age as the IV and current state conditions as the DV. For this work, a framework is created and implemented that utilizes a PCR model to build upon accepted practices for degradation modeling to enhance and possibly augment future prediction capabilities. The model was applied to pairs of location and pavement family and reveals several findings: the selected …

Go to article

Identifying Four Year Average Cloud Field Regimes From World Wide Merged Cloud Analysis Dataset By Way Of K-Means Clustering, Stewart G. Almeida Mar 2021

Identifying Four Year Average Cloud Field Regimes From World Wide Merged Cloud Analysis Dataset By Way Of K-Means Clustering, Stewart G. Almeida

Theses and Dissertations

Joint histograms of cloud top height (CTH) and optical depth (OD) are created using the World-Wide Merged Cloud Analysis (WWMCA) dataset over a four year period (2014-2017) to identify average cloud field regimes and assess the application of utilizing the WWMCA dataset with the AFIT Sensor and Scene Emulation Tool (ASSET). Two selected regions encompassing the Florida peninsula and a portion of the Pacific Ocean off the west-central coast of South America are examined over the months of January and July. Cloud field regimes are identified by running generated hourly OD-CTH histograms through k-means clustering, with optimal cluster number ( …

Go to article

Comparison Of Spatial Precipitation Forecasts With A Satellite Dataset, Andrew C. Siebels Mar 2021

Comparison Of Spatial Precipitation Forecasts With A Satellite Dataset, Andrew C. Siebels

Theses and Dissertations

The purpose of this research is to analyze and compare global precipitation data from the Climate Forecast System Version 2 (CFSv2) with the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN)-Climate Data Record (CDR) to improve long term precipitation forecasting. The CFSv2 has a 0.5-degree resolution which will provide model data for precipitation forecasts. The PERSIANN-CDR is a satellite derived daily 0.25-degree dataset with 37 years of global precipitation coverage 60 N to 60 S. The 0-to-10, 15-to-25, 55-to-65, and 80-to-90 day forecast time frames will then be analyzed for accuracy, and a quantile mapping (QM) technique …

Go to article

Ccsfs/Ksc Total Lightning Warning Radii Optimization For Merlin Using Preexisting Lightning Areas, Kimberly G. Holland Mar 2021

Ccsfs/Ksc Total Lightning Warning Radii Optimization For Merlin Using Preexisting Lightning Areas, Kimberly G. Holland

Theses and Dissertations

The purpose of this research is to optimize lightning warning radii specifications for the 45th Space Wing (45 SW), thus reducing the number of unnecessary warnings that delay ground processing needed for space launch execution at Kennedy Space Center and Cape Canaveral Space Force Station. This thesis sought to answer two key research questions addressing: 1) What radius reduction effectively balances both safety and operations and do reduction recommendations from previous research align with results from the new detection system? 2) What insights can be gained from comparing measurement results for seasonal lightning events as well as lightning types? This …

Go to article

Behavior Of Lightning In Developing Storms, Erick A. Tello Mar 2021

Behavior Of Lightning In Developing Storms, Erick A. Tello

Theses and Dissertations

Air Force weather squadrons issue a warning when lightning activity is observed within 5 nautical miles (NM) of protected areas. Upon receiving this warning, personnel outdoors are expected to pause work and move inside. Studies sponsored by the 45th Weather Squadron (45 WS) have concluded that the 5 NM warning radius can be safely reduced for well-developed storms. This thesis investigates whether radii for storms in early development can also be reduced. Our research develops algorithms to partition lightning sensor data into storms. Next, storms are filtered to their earliest lightning events, and the study calculates distances between successive early …

Go to article

Arctic Observations And Numerical Simulations Of Surface Wind Effects On Multi-Angle Snowflake Camera Measurements, Kyle E. Fitch, Chaoxun Hang, Ahmad Talaei, Timothy Garrett Jan 2021

Arctic Observations And Numerical Simulations Of Surface Wind Effects On Multi-Angle Snowflake Camera Measurements, Kyle E. Fitch, Chaoxun Hang, Ahmad Talaei, Timothy Garrett

Faculty Publications

Ground-based measurements of frozen precipitation are heavily influenced by interactions of surface winds with gauge-shield geometry. The Multi-Angle Snowflake Camera (MASC), which photographs hydrometeors in free-fall from three different angles while simultaneously measuring their fall speed, has been used in the field at multiple midlatitude and polar locations both with and without wind shielding. Here, we present an analysis of Arctic field observations – with and without a Belfort double Alter shield – and compare the results to computational fluid dynamics (CFD) simulations of the airflow and corresponding particle trajectories around the unshielded MASC. MASC-measured fall speeds compare well with …

Go to article

Physics-Constrained Hyperspectral Data Exploitation Across Diverse Atmospheric Scenarios, Nicholas M. Westing Sep 2020

Physics-Constrained Hyperspectral Data Exploitation Across Diverse Atmospheric Scenarios, Nicholas M. Westing

Theses and Dissertations

Hyperspectral target detection promises new operational advantages, with increasing instrument spectral resolution and robust material discrimination. Resolving surface materials requires a fast and accurate accounting of atmospheric effects to increase detection accuracy while minimizing false alarms. This dissertation investigates deep learning methods constrained by the processes governing radiative transfer to efficiently perform atmospheric compensation on data collected by long-wave infrared (LWIR) hyperspectral sensors. These compensation methods depend on generative modeling techniques and permutation invariant neural network architectures to predict LWIR spectral radiometric quantities. The compensation algorithms developed in this work were examined from the perspective of target detection performance using …

Go to article

Measurements Of Optical Turbulence Over 149-Km Path, Jack E. Mccrae, Santasri Bose-Pillai, Steven T. Fiorino, Aaron J. Archibald, Joel Meoak, Brannon Elmore, Thomas Kesler, Christopher A. Rice Jul 2020

Measurements Of Optical Turbulence Over 149-Km Path, Jack E. Mccrae, Santasri Bose-Pillai, Steven T. Fiorino, Aaron J. Archibald, Joel Meoak, Brannon Elmore, Thomas Kesler, Christopher A. Rice

Faculty Publications

An experiment was conducted to study turbulence along a 149-km path between the Mauna Loa and Haleakala mountain tops using digital cameras and light-emitting diode (LED) beacons. Much of the path is over the ocean, and a large portion of the path is 3 km above sea level. On the Mauna Loa side, six LED beacons were placed in a roughly linear array with pair spacings from 7 to 62 m. From the Haleakala side, a pair of cameras separated by 83.8 cm observed these beacons. Turbulence along the path induces tilts on the wavefronts, which results in displacements of …

Go to article

Turbulence Profiling Using Pupil Plane Wavefront Data Derived Fried Parameter Values For A Dynamically Ranged Rayleigh Beacon, Steven M. Zuraski, Elizabeth Beecher, Jack E. Mccrae, Steven T. Fiorino Jul 2020

Turbulence Profiling Using Pupil Plane Wavefront Data Derived Fried Parameter Values For A Dynamically Ranged Rayleigh Beacon, Steven M. Zuraski, Elizabeth Beecher, Jack E. Mccrae, Steven T. Fiorino

Faculty Publications

Long-range optical imaging applications are typically hindered by atmospheric turbulence. The effect of turbulence on an imaging system can manifest itself as an image blur effect usually quantified by the phase distortions present in the system. The blurring effect can be understood on the basis of the measured strength of atmospheric optical turbulence along the propagation path and its impacts on phase perturbation statistics within the imaging system. One method for obtaining these measurements is by the use of a dynamically ranged Rayleigh beacon system that exploits strategically varied beacon ranges along the propagation path, effectively obtaining estimates of the …

Go to article

Wave-Optics Investigation Of Turbulence Thermal Blooming Interaction: I. Using Steady-State Simulations, Mark F. Spencer Jul 2020

Wave-Optics Investigation Of Turbulence Thermal Blooming Interaction: I. Using Steady-State Simulations, Mark F. Spencer

Faculty Publications

Part I of this two-part paper uses wave-optics simulations to look at the Monte Carlo averages associated with turbulence and steady-state thermal blooming (SSTB). The goal is to investigate turbulence thermal blooming interaction (TTBI). At wavelengths near 1 μm, TTBI increases the amount of constructive and destructive interference (i.e., scintillation) that results from high-power laser beam propagation through distributed-volume atmospheric aberrations. As a result, we use the spherical-wave Rytov number and the distortion number to gauge the strength of the simulated turbulence and SSTB. These parameters simplify greatly given propagation paths with constant atmospheric conditions. In addition, we use the …

Go to article

Implications Of Four-Dimensional Weather Cubes For Improved Cloud-Free Line-Of-Sight Assessments Of Free-Space Optical Communications Link Performance, Steven T. Fiorino, Santasri Bose-Pillai, Jaclyn Schmidt, Brannon Elmore, Kevin J. Keefer Jul 2020

Implications Of Four-Dimensional Weather Cubes For Improved Cloud-Free Line-Of-Sight Assessments Of Free-Space Optical Communications Link Performance, Steven T. Fiorino, Santasri Bose-Pillai, Jaclyn Schmidt, Brannon Elmore, Kevin J. Keefer

Faculty Publications

We advance the benefits of previously reported four-dimensional (4-D) weather cubes toward the creation of high-fidelity cloud-free line-of-sight (CFLOS) beam propagation for realistic assessment of autotracked/dynamically routed free-space optical (FSO) communication datalink concepts. The weather cubes accrue parameterization of optical effects and custom atmospheric resolution through implementation of numerical weather prediction data in the Laser Environmental Effects Definition and Reference atmospheric characterization and radiative transfer code. 4-D weather cube analyses have recently been expanded to accurately assess system performance (probabilistic climatologies and performance forecasts) at any wavelength/frequency or spectral band in the absence of field tests and employment data. The …

Go to article

Wave-Optics Investigation Of Turbulence Thermal Blooming Interaction: Ii. Using Time-Dependent Simulations, Mark F. Spencer Jul 2020

Wave-Optics Investigation Of Turbulence Thermal Blooming Interaction: Ii. Using Time-Dependent Simulations, Mark F. Spencer

Faculty Publications

Part II of this two-part paper uses wave-optics simulations to look at the Monte Carlo averages associated with turbulence and time-dependent thermal blooming (TDTB). The goal is to investigate turbulence thermal blooming interaction (TTBI). At wavelengths near 1 μm, TTBI increases the amount of constructive and destructive interference (i.e., scintillation) that results from high-power laser beam propagation through distributed-volume atmospheric aberrations. As a result, we use the spherical-wave Rytov number, the number of wind-clearing periods, and the distortion number to gauge the strength of the simulated turbulence and TDTB. These parameters simply greatly given propagation paths with constant atmospheric conditions. …

Go to article

Machine Learning Modeling Of Horizontal Photovoltaics Using Weather And Location Data, Christil Pasion, Torrey J. Wagner, Clay Koschnick, Steven J. Schuldt, Jada B. Williams, Kevin Hallinan May 2020

Machine Learning Modeling Of Horizontal Photovoltaics Using Weather And Location Data, Christil Pasion, Torrey J. Wagner, Clay Koschnick, Steven J. Schuldt, Jada B. Williams, Kevin Hallinan

Faculty Publications

Solar energy is a key renewable energy source; however, its intermittent nature and potential for use in distributed systems make power prediction an important aspect of grid integration. This research analyzed a variety of machine learning techniques to predict power output for horizontal solar panels using 14 months of data collected from 12 northern-hemisphere locations. We performed our data collection and analysis in the absence of irradiation data—an approach not commonly found in prior literature. Using latitude, month, hour, ambient temperature, pressure, humidity, wind speed, and cloud ceiling as independent variables, a distributed random forest regression algorithm modeled the combined …

Go to article

Learning Set Representations For Lwir In-Scene Atmospheric Compensation, Nicholas M. Westing, Kevin C. Gross, Brett J. Borghetti, Jacob A. Martin, Joseph Meola Apr 2020

Learning Set Representations For Lwir In-Scene Atmospheric Compensation, Nicholas M. Westing, Kevin C. Gross, Brett J. Borghetti, Jacob A. Martin, Joseph Meola

Faculty Publications

Atmospheric compensation of long-wave infrared (LWIR) hyperspectral imagery is investigated in this article using set representations learned by a neural network. This approach relies on synthetic at-sensor radiance data derived from collected radiosondes and a diverse database of measured emissivity spectra sampled at a range of surface temperatures. The network loss function relies on LWIR radiative transfer equations to update model parameters. Atmospheric predictions are made on a set of diverse pixels extracted from the scene, without knowledge of blackbody pixels or pixel temperatures. The network architecture utilizes permutation-invariant layers to predict a set representation, similar to the work performed …

Go to article

An Analysis Of A Lighting Prediction Threshold For 45th Weather Squadron Electric Field Mill Data, Charles A. Skrovan Mar 2020

An Analysis Of A Lighting Prediction Threshold For 45th Weather Squadron Electric Field Mill Data, Charles A. Skrovan

Theses and Dissertations

The mission of the 45th Weather Squadron (45 WS) is to “exploit the weather to assure safe access to air and space” for Patrick Air Force Base, Cape Canaveral Air Force Station (CCAFS), and Kennedy Space Center (KSC) in support of various operations (United States Air Force, n.d.). To support that mission the 45 WS hosts a suite of weather detection instruments that include a lightning warning system that consists of an array of 31 electric field mills (EFM) and a lightning detection and ranging system (Department of the Air Force, 1976). Electric field mills at Cape Canaveral continuously record …

Go to article

Validation Technique For Modeled Bottomside Ionospheres Via Ray Tracing, Kevin S. Burg Mar 2020

Validation Technique For Modeled Bottomside Ionospheres Via Ray Tracing, Kevin S. Burg

Theses and Dissertations

A new method for validating ionosphere models using High Frequency (HF) angle of arrival (AoA) data is presented. AoA measurements from a field campaign held at White Sands Missile Range, New Mexico, USA in January 2014 provide the actual elevation angle, azimuth and group delay results from 10 transmitter-receiver circuits. Simulated AoAs are calculated by ray tracing through the electron density profiles predicted from the ionosphere models hosted by NASA's Community Coordinated Modeling Center: IRI-2016, USU-GAIM, GITM, CTIPe, TIE-GCM, and SAMI3. Through the implementation of metrics including Mean Absolute Error, Prediction Efficiency, Correlation Coefficient, and others, we are able to …

Go to article

Next-Generation Air Force Weather Metrics Via Bayes Cost Analysis, Brandon M. Bailey Mar 2020

Next-Generation Air Force Weather Metrics Via Bayes Cost Analysis, Brandon M. Bailey

Theses and Dissertations

This research proposes a new methodology for U.S. Air Force weather forecast metrics. Military weather forecasters are essentially statistical classifiers. They categorize future conditions into an operationally relevant category based on current data, much like an Artificial Neural Net or Logistic Regression model. There is extensive literature on statistically-based metrics for these types of classifiers. Additionally, in the U.S. Air Force, forecast errors (errors in classification) have quantifiable operational costs and benefits associated with incorrect or correct classification decisions. There is a methodology in the literature, Bayes Cost, which provides a structure for creating statistically rigorous metrics for classification decisions …

Go to article

Detection Of Reconnection Signatures In Solar Flares, Taylor R. Whitney Mar 2020

Detection Of Reconnection Signatures In Solar Flares, Taylor R. Whitney

Theses and Dissertations

Solar flare forecasting is limited by the current understanding of mechanisms that govern magnetic reconnection, the main physical phenomenon associated with these events. As a result, forecasting relies mainly on climatological correlations to historical events rather than the underlying physics principles. Solar physics models place the neutral point of the reconnection event in the solar corona. Correspondingly, studies of photospheric magnetic fields indicate changes during solar flares -- particularly in relation to the field helicity -- on the solar surface as a result of the associated magnetic reconnection. This study utilizes data from the Solar Dynamics Observatory (SDO) Helioseismic and …

Go to article

Determining Bulk Aerosol Absorption From Off Axis Backscattering Using Rayleigh Beacon Laser Pulses, Julie C. Grossnickle Mar 2020

Determining Bulk Aerosol Absorption From Off Axis Backscattering Using Rayleigh Beacon Laser Pulses, Julie C. Grossnickle

Theses and Dissertations

Aerosol absorption and scattering can play a key role in degrading high energy laser performance in the form of thermal blooming and beam attenuation. Aerosol absorption properties are not completely understood, and thus affect how we are able to quantify expected high energy laser weapon performance. The Air Force Institute of Technology Center for Directed Energy (AFIT CDE) developed both Laser Environmental Effects Definition and Reference (LEEDR) and the High Energy Laser End-to-End Operational Simulation (HELEEOS) code to characterize atmospheric radiative transfer effects and evaluate expected directed energy weapon system performance. These packages enable modeling of total irradiance at given …

Go to article

First Prev Next Last