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Quantitative Measurement Of Lightning Induced Electron Precipitaion Using Vlf Remote Sensing
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Book Synopsis Quantitative Measurement of Lightning-induced Electron Precipitaion Using VLF Remote Sensing by : William Bolton Peter
Download or read book Quantitative Measurement of Lightning-induced Electron Precipitaion Using VLF Remote Sensing written by William Bolton Peter and published by . This book was released on 2007 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Global Quantification of Lightning-induced Electron Precipitation Using Very Low Frequency Remote Sensing by : Benjamin Randolph Tucker Cotts
Download or read book Global Quantification of Lightning-induced Electron Precipitation Using Very Low Frequency Remote Sensing written by Benjamin Randolph Tucker Cotts and published by Stanford University. This book was released on 2011 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observations of lightning-induced electron precipitation (LEP) events at three geographic regions show characteristics which systematically vary with both longitude and hemisphere. These observations are quantitatively interpreted with the use of a novel model of atmospheric backscatter designed to be used to predict the characteristics of LEP events at any longitude and mid-latitude L-shell by accounting for the effects of precipitating electrons which are backscattered from the atmosphere. The new model of atmospheric backscatter (ABS) is based upon the calculation of ~16,000 individual atmospheric backscatter responses for monoenergetic electron beams with a single incident pitch angle using a Monte Carlo model of atmospheric interactions which tracks the full gyration of each individual precipitating electron around the magnetic field line as it enters the atmosphere, accounting for the dynamic friction force and angular diffusion as well as the production of new electrons via ionization. The ABS model includes the effects of the asymmetric magnetic field in calculations of the pitch angle of backscattered electrons entering the conjugate hemisphere and accounts for the different strength of the magnetic field at conjugate points of the same field line. This magnetic field difference causes the equatorial loss cone angle to vary greatly between hemispheres and with longitude which results in significant and systematic differences in LEP signatures at various locations. A realistic distribution of precipitating electrons is inserted into the ABS model by calculating the energy and pitch angle distribution which results from the resonant interactions of a lightning-initiated magnetospherically reflecting whistler wave with trapped radiation belt particles. This calculation is accomplished by extensive magnetospheric ray-tracing, accounting for Landau damping as well as spatial and temporal dispersion of the whistler wave. This distribution of precipitating electrons is then inserted into the ABS model at three separate longitudes (260 degrees east (1N) and 290 degrees east (2N) in the Northern Hemisphere, and 295 degrees east (2S) in the Southern Hemisphere, corresponding to the Central United States, the East Coast of the United States, and Palmer, Antarctica, respectively) and the deposition results are compared with VLF remote sensing data collected on nearly north-south great circle paths (GCPs) allowing for isolation of longitudinal effects on LEP. Results predicted by the model and confirmed by data indicate that all four primary LEP characteristics exhibit longitudinal and hemispheric dependencies which can be explained in terms of backscatter of precipitating electrons from the atmosphere. The mean observed LEP onset delay exhibits a hemispheric dependence at these longitudes with events in the northern hemisphere delayed by one bounce period relative to direct precipitation and advanced by one-half bounce period in the southern hemisphere. The mean observed onset duration exhibits a longitudinal dependence with events observed at locations 1N and 2S persisting for three bounce periods, and at location 2N for two bounce periods. The amplitude change and recovery time also show a longitudinal and hemispheric dependence based upon the relative sizes of the loss cones at different longitudes with LEP events produced at location 1N consistently larger than at location 2N, and observed recovery times at location 2N longer than at 1N which are still longer than at 2S. All of these results are explained in terms of backscatter of precipitating electrons from the atmosphere and ABS model shows that by accounting for atmospheric backscatter it is possible to accurately predict all the observable characteristics of LEP events. Furthermore, by combining these effects with previously calculated radiation belt electron loss rates due to lightning at a single location, it is possible to estimate the global loss of radiation belt electrons due to lightning.
Book Synopsis Global Quantification of Lightning-induced Electron Precipitation Using Very Low Frequency Remote Sensing by : Benjamin Randolph Tucker Cotts
Download or read book Global Quantification of Lightning-induced Electron Precipitation Using Very Low Frequency Remote Sensing written by Benjamin Randolph Tucker Cotts and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Observations of lightning-induced electron precipitation (LEP) events at three geographic regions show characteristics which systematically vary with both longitude and hemisphere. These observations are quantitatively interpreted with the use of a novel model of atmospheric backscatter designed to be used to predict the characteristics of LEP events at any longitude and mid-latitude L-shell by accounting for the effects of precipitating electrons which are backscattered from the atmosphere. The new model of atmospheric backscatter (ABS) is based upon the calculation of ~16,000 individual atmospheric backscatter responses for monoenergetic electron beams with a single incident pitch angle using a Monte Carlo model of atmospheric interactions which tracks the full gyration of each individual precipitating electron around the magnetic field line as it enters the atmosphere, accounting for the dynamic friction force and angular diffusion as well as the production of new electrons via ionization. The ABS model includes the effects of the asymmetric magnetic field in calculations of the pitch angle of backscattered electrons entering the conjugate hemisphere and accounts for the different strength of the magnetic field at conjugate points of the same field line. This magnetic field difference causes the equatorial loss cone angle to vary greatly between hemispheres and with longitude which results in significant and systematic differences in LEP signatures at various locations. A realistic distribution of precipitating electrons is inserted into the ABS model by calculating the energy and pitch angle distribution which results from the resonant interactions of a lightning-initiated magnetospherically reflecting whistler wave with trapped radiation belt particles. This calculation is accomplished by extensive magnetospheric ray-tracing, accounting for Landau damping as well as spatial and temporal dispersion of the whistler wave. This distribution of precipitating electrons is then inserted into the ABS model at three separate longitudes (260 degrees east (1N) and 290 degrees east (2N) in the Northern Hemisphere, and 295 degrees east (2S) in the Southern Hemisphere, corresponding to the Central United States, the East Coast of the United States, and Palmer, Antarctica, respectively) and the deposition results are compared with VLF remote sensing data collected on nearly north-south great circle paths (GCPs) allowing for isolation of longitudinal effects on LEP. Results predicted by the model and confirmed by data indicate that all four primary LEP characteristics exhibit longitudinal and hemispheric dependencies which can be explained in terms of backscatter of precipitating electrons from the atmosphere. The mean observed LEP onset delay exhibits a hemispheric dependence at these longitudes with events in the northern hemisphere delayed by one bounce period relative to direct precipitation and advanced by one-half bounce period in the southern hemisphere. The mean observed onset duration exhibits a longitudinal dependence with events observed at locations 1N and 2S persisting for three bounce periods, and at location 2N for two bounce periods. The amplitude change and recovery time also show a longitudinal and hemispheric dependence based upon the relative sizes of the loss cones at different longitudes with LEP events produced at location 1N consistently larger than at location 2N, and observed recovery times at location 2N longer than at 1N which are still longer than at 2S. All of these results are explained in terms of backscatter of precipitating electrons from the atmosphere and ABS model shows that by accounting for atmospheric backscatter it is possible to accurately predict all the observable characteristics of LEP events. Furthermore, by combining these effects with previously calculated radiation belt electron loss rates due to lightning at a single location, it is possible to estimate the global loss of radiation belt electrons due to lightning.
Book Synopsis Global and Seasonal Effects of Lightning-induced Electron Precipitation by : Austin Patrick Sousa
Download or read book Global and Seasonal Effects of Lightning-induced Electron Precipitation written by Austin Patrick Sousa and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Surrounding the Earth are two shells of high-energy electrons and ions known as the Van Allen Radiation Belts, the dynamics of which are governed by a complex balance of sources and loss processes, collectively resulting in populations which persist between days and months. The global distribution of lightning discharges has been theorized to be an important loss function for radiation belt electrons through a process known as Lightning- Induced Electron Precipitation (LEP). However, a lack of in situ measurements has precluded a quantitative global study. We present an investigation of the spatial and temporal morphology of lightning-induced electron precipitation. We seek to quantitatively determine the regions in space, time, and electron energy, where LEP may be of importance, using a combination of numerical raytracing and resonant interaction modeling, driven by a realistic measurement of global lightning activity from the GLD360 lightning detection network. First, using cold plasma numerical raytracing, we provide an estimate of the persistent radio energy in the near-Earth space environment due to whistler-mode, VLF waves generated by terrestrial cloud-to-ground lightning flashes. Variation is explored with respect to L-shell, longitude, frequency, and geomagnetic activity using the Kp index. We include updated ionospheric absorption curves and an improved 4-dimensional interpolation algorithm. We find that the persistent energy decays logarithmically with increasing L-shell and frequency. We then apply our raytracing and interpolation apparatus to simulate the precipitating electron flux resulting from single lightning strokes, and extrapolate over the GLD360 dataset to determine estimated locations of elevated electron precipitation. We compute the estimated lifetime of geomagnetically trapped electron populations, subject solely to LEP-induced losses, as a function of L-shell and electron energy. Our estimates are consistent with measurements in the 100keV -- 1 MeV energy range; however our results suggest that LEP may be a substantial loss mechanism for lower energy, suprathermal electrons in the 100 eV -- 10 keV range. We do not find any notable enhancement in the slot region, suggesting that resonant interactions with lightning-generated whistlers are not a significant contributor to slot region morphology. Finally we present a design for a VLF radio receiver, intended for deployment on a 3-unit CubeSat bus, which can be used in conjunction with an onboard electron energy spectrometer to make direct, in situ measurements of precipitating electrons and their causative whistler waves. The receiver is designed with radiation tolerance in mind, and includes a novel onboard data processing system, implemented entirely in an field-programmable gate array (FPGA) using the Verilog hardware description language.
Book Synopsis Global Assessment of Precipitation of Radiation Belt Electrons by Electromagnetic Waves from Lightning by : Erin Selser Gemelos
Download or read book Global Assessment of Precipitation of Radiation Belt Electrons by Electromagnetic Waves from Lightning written by Erin Selser Gemelos and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Lightning discharges are well known sources of electromagnetic radiation in the frequency range of a few Hz to many MHz, with the most intense radiation typically being in the range of 5--10 kHz. Electromagnetic waves originating in lightning discharges often propagate through the most densely ionized regions of the Earth's atmosphere and populate the radiation belts. High-energy electrons in this region constitute a hazard to the increasing number of scientific and commercial spacecraft that orbit the Earth, and quantitative understanding of this radiation and its sources and losses are thus important. Electromagnetic whistler waves injected into the radiation belts by lightning discharges can pitch-angle scatter the energetic electrons and cause them to precipitate out of their stably trapped radiation belt orbits and onto the dense upper atmosphere of the Earth. This dissertation examines the detection of lighting-induced energetic electron precipitation via long-term analysis of in-situ observations of drift loss cone fluxes (i.e., fluxes destined to be precipitated over the South Atlantic Anomaly within ~2 hours). The primary measurement tool used is an energetic electron detector (IDP) on board the DEMETER satellite--a French micro-satellite in a sun-synchronous low Earth orbit. Energetic electron flux data are analyzed alongside ground-based lightning data recorded by the National Lightning Detection Network (NLDN) to determine the relationship between drift loss cone fluxes and lightning. While lighting-induced electron precipitation events occur globally, the best region for making in-situ observations of fluctuations in drift loss cone fluxes is over the continental United States. Measurements of VLF wave activity in the typical frequency range of lightning-generated whistler waves (5--10 kHz) on DEMETER show a substantial increase of electromagnetic wave power over the United States, particularly during the northern summer months when lightning activity is at its highest. Analysis of particle precipitation data on the DEMETER spacecraft over a three-year period shows that energetic electron fluxes in the drift loss cone exhibit a seasonal dependence consistent with lightning-induced electron precipitation (LEP) being an important source of loss of such energetic radiation. Over the United States, energetic electron fluxes in the slot region (2
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Design and Mplementation of The VLF Wave and Particle Precipitation Mapper Sensor Suite by : Steven.?UNAUTHORIZED. Ingram
Download or read book Design and Mplementation of The VLF Wave and Particle Precipitation Mapper Sensor Suite written by Steven.?UNAUTHORIZED. Ingram and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The VLF Wave and Particle precipitation Mapper (VPM) Sensor Suite will serve as a complement to ongoing DoD programs aimed at qualification of controlled precipitation of energetic electron radiation by ELF/VLF whistler-mode waves. Two benefitting programs are the Air Force Demonstration and Science Experiment (DSX) satellite mission, and the High frequency Active Auroral Research Program (HAARP). New capabilities provided by VPM are afforded by a dual detector configuration that provides sensitive measurements of energetic electrons both just-inside and just-outside the bounce loss cone, and by wave receivers with GPS-based timing facilitating interferometric measurements of electron density irregularities. The VPM sensor suite will make use of novel VLF micro-receivers consisting of radiation-hardened (up to a 2 Mrad) Low Noise Amplifier (LNA), Anti-Aliasing Filter (AAF), and Analog-to-Digital Converter (ADC) application specific integrated circuits (ASICs) developed over the past 6 years in the context of three student PhD theses. These devices provide the capability to conduct ELF/VLF observations at extremely low power and weight, while maintaining the high degree of sensitivity, resolution and dynamic range required in such measurements. Research areas of VPM will focus on determining energy spectra, temporal signatures, and spatial extent of energetic electron precipitation bursts induced by discrete whistler-mode waves, launched by ground-based sources: (i) lightning discharges, (ii) VLF transmitter signals (e.g., NPM, NAA, etc.), and (iii) ELF/VLF waves injected by modulated HF heating (i.e., HAARP). VPM will measure waves in broadband fashion so as to identify those from different sources, with high time and frequency resolution. It will simultaneously measure energetic particles with high sensitivity (large geometric factors), high time and energy resolution, so as to assess cause and affect relationships and determine calibrated theoretical models (by determining the flux levels that result from given levels of wave power density). VPM will also measure transmitted VLF wave intensity from the DSX/WIPER transmitter and determine transmitter efficiency, effective plasma sheath impedance and confirm dynamics of transmission process.
Book Synopsis Antarctic Journal of the United States by :
Download or read book Antarctic Journal of the United States written by and published by . This book was released on 1989 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Lightning and Ionospheric Remote Sensing Using VLF/ELF Radio Atmospherics by : Steven Andrew Cummer
Download or read book Lightning and Ionospheric Remote Sensing Using VLF/ELF Radio Atmospherics written by Steven Andrew Cummer and published by . This book was released on 1997 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Outer Zone Electron Precipitation Produced by a VLF Transmitter by : Alfred L. Vampola
Download or read book Outer Zone Electron Precipitation Produced by a VLF Transmitter written by Alfred L. Vampola and published by . This book was released on 1988 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using high resolution pitch angle measurements made by a magnetic focusing electron spectrometer on the S3-3 satellite while in the drift loss cone region of the magnetosphere, characteristics of fluxes of 108 keV to 654 keV electrons precipitated in the inner zone, in the slot region, and in the outer zone of the magnetosphere are all shown to be consistent with the precipitation having been produced by the same ground-based VLF transmitter, UMS. Pitch angle measurements are used to locate the longitude of precipitation. The temporal pattern of transmitter operation obtained from synoptic data from a ground-based VLF receiver is used along with drift-rate calculations to predict the electron energies as a function of L-shell which should be observable by the S3-3 instrument. The predicted energy response is then compared with the in-situ observations, getting complete agreement. Finally, wave-particle resonance calculations are made for each of the three regions. The study indicates that ground-based VLF transmitters, which have previously been shown to produce precipitation in the inner zone and slot regions, are almost certainly instrumental in precipitating electrons in the outer zone also.
Book Synopsis VLF Transmission Induced Slot Electron Precipitation by : Alfred L. Vampola
Download or read book VLF Transmission Induced Slot Electron Precipitation written by Alfred L. Vampola and published by . This book was released on 1977 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analysis of electron observations in the drift and bounce loss cones of the slot region of the magnetosphere indicates that the predominant mode in which electrons in the 100 to 400 keV energy range arrive in the drift loss cone is via discrete events. These events are usually traceable back to the vicinity of a high-power-level VLF transmitter. No gradual buildup of electron flux, proceeding eastward from the South Atlantic Anomaly, is observed. Estimates of the loss rate due to the discrete events show that this process can result in a depletion of 50% per day of the electron flux in the slot region. The wave-particle interaction must occur relatively low on the field line (lambda approximately 30 deg to 50 deg) because of the relationship of particle energies and wave frequencies involved. Additional scattering of the particles near the equator, either by power-line harmonic emissions or naturally occurring ELF hiss, is required to transport the particles to the lower interaction region. (Author).
Download or read book Radio Science written by and published by . This book was released on 2003 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Remote Sensing and Statistical Analysis of the Lightning-ionosphere Interaction by : Patrick R. Blaes
Download or read book Remote Sensing and Statistical Analysis of the Lightning-ionosphere Interaction written by Patrick R. Blaes and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Lightning is an extremely frequent phenomenon and an important part of the global electrical circuit with an average of 2000 active storms globally every day and an average flash rate of 40-50 flashes per second. Each lightning stroke radiates an intense electromagnetic pulse (EMP) in the VLF/LF frequency band (300 Hz--300 kHz). This EMP propagates efficiently in the earth-ionosphere waveguide and can be measured long distances away on the ground, in excess of several thousand kilometers. The upwardly directed part of the EMP interacts with and heats plasma in the Earth's ionosphere. Some of this energy propagates through the ionosphere where it enters the magnetosphere as a whistler-mode wave which may resonantly interact with energetic electrons in the Earth's radiation belts. Intense lightning EMPs may produce brief optical flashes known as ``elves'' in the lower part of the ionosphere ($\sim$88km altitude). Elves, first discovered in 1991, appear as rapidly expanding rings of light centered about the causative lighting stroke. They have durations of less than 1 ms and radial extents up to several hundred kilometers. In this work, we present ground-based observations of elves made using an optical free-running photometer along with VLF/LF observations of the lightning EMP magnetic field. We use these experimental observations to investigate the properties of the lightning return stroke that control the production of optical elve emissions. Two summers of data containing observations of over six hundred elves along with the LF magnetic field of the associated lightning are analyzed. By training a classifier on features of the EMP ground wave, we find that we are able to accurately predict whether or not a stroke produced an elve. Additionally, we show that the geometric features of elves can be used to estimate the current return stroke speed of lightning. This estimation constitutes the first experimental measurement of the return stroke speed that relates directly to the current propagation rather than its optical manifestation. Finally, we use data from the GLD360 lightning geolocation network to extrapolate the global elve production rate and to estimate the amount of ionospheric heating due to lightning.
Book Synopsis VLF/LF Remote Sensing of Transient and Localized Disturbances of the Lower Ionosphere Associated with Lightning Discharges by : Umran S. Inan
Download or read book VLF/LF Remote Sensing of Transient and Localized Disturbances of the Lower Ionosphere Associated with Lightning Discharges written by Umran S. Inan and published by . This book was released on 1990 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: High resolution measurements of subionospheric VLF/LF signals are now established as a powerful remote sensing tool for investigation of transient and localized ionospheric disturbances associated with atmospheric lightning discharges. Events usually consist of sudden (2 s) changes in amplitude and/or phase followed by relatively slow (10-100 s) recovery to background levels. This paper discusses recent results from a new series of observations conducted at Arecibo, Puerto Rico and at Huntsville, Alabama. The subionospheric VLF paths from two different transmitters to these two sites are nearly collinear, allowing for identification of the location of the disturbed ionospheric regions. Events observed on some very short paths indicate that selective excitation of waveguide modes can be used to extract information on the energy spectra of precipitating particles. In one case, on 23 February 1990, an extremely high rate of event activity (60 events/hr) was observed at Huntsville on the 48.5 kHz signal from Silver Creek, Nebraska, with amplitude changes of as much as 15 dB in individual events.
Book Synopsis US Antarctic Program Continuation by :
Download or read book US Antarctic Program Continuation written by and published by . This book was released on 1980 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Lightning: Principles, Instruments and Applications by : Hans Dieter Betz
Download or read book Lightning: Principles, Instruments and Applications written by Hans Dieter Betz and published by Springer Science & Business Media. This book was released on 2008-12-04 with total page 641 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lightning represents a natural phenomenon of substantial interest. Due to its complex nature, research continues in many countries and reveals amazing results. Lightning is actively observed because of its relevance to Earth climate and air composition in addition to the classical aspects of related human fatalities and damage to forests, buildings, power lines, aircraft, structures and electronic devices. In this volume, the most important contemporary questions on lightning are addressed and analyzed under many experimental and theoretical aspects. Lightning detection techniques using ground-based and space-borne methods are described, along with network engineering and statistical analysis. Contributions detail research on atmospheric electricity, cloud physics, lightning physics, modeling of electrical storms and middle atmospheric events. Special phenomena such as triggered lightning and sprite observations are examined. Lightning-induced nitrogen oxides and their effects on atmospheric chemistry and climate are discussed. Each topic is presented by international experts in the field. Topics include: * air chemistry * convective storms * infrasound from lightning * lightning and climate change * lightning and precipitation * lightning and radiation * lightning and supercells * lightning and thunderstorms * lightning detection * lightning from space * lighting protection * lightning return strokes * observations and interpretations * spatial distribution and frequency * triggered lightning * weather extremes
Book Synopsis Introduction to Geomagnetically Trapped Radiation by : Martin Walt
Download or read book Introduction to Geomagnetically Trapped Radiation written by Martin Walt and published by Cambridge University Press. This book was released on 1994-11-03 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an introductory textbook on the physical processes occurring in the Earth's radiation belts. The presentation is at the advanced undergraduate or first year graduate level, and it is appropriate for students who intend to work in some aspect of magnetospheric physics. The treatment is quantitative and provides the mathematical basis for original work in this subject. The equations describing the motion of energetic ions and electrons in the geomagnetic field are derived from basic principles, and concepts such as magnetic field representations, guiding centre motion, adiabatic invariance, and particle distribution functions are presented in a detailed and accessible manner. Relevant experimental techniques are reviewed and a summary is given of the intensity and energy spectra of the particle populations in the Earth's radiation belts. Problem sets are included as well as appendices of tables, graphs and frequently used formulas.
