Download or read book Nonlinear Equatorial Spread F Dependence on Altitude of the F Peak and Bottomside Background Electron Density Gradient Scale Length written by S. L. Ossakow and published by . This book was released on 1978 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Four different two dimensional (perpendicular to the ambient magnetic field), plasma fluid-type, numerical simulations following the nonlinear evolution of the collisional Rayleigh-Taylor instability in the nighttime equatorial F region ionosphere have been performed. Realistic altitude dependent ion-neutral collision frequencies, recombination rates, and ambient electron density profiles were used. In three cases (ESF 0, 1, 3) the electron density profile was kept constant, with a minimum bottomside background electron density gradient scale length L about 10 km, but the altitude of the F peak was changed, with F peak altitudes at 340, 350, and 430 km. All cases resulted in bottomside growth of the instability (Spread F) with dramatically different time scales for development. Plasma density depletions were produced on the bottomside with rise velocities, produced by nonlinear polarization E x B forces, of 2.5, 12, and 160 m/sec, and percentage depletions of 16, 40, and 85, respectively. High altitude of the F peak, small bottomside electron density gradient scale lengths, and large percentage depletions yield large vertical bubble rise velocities, with the first two conditions favoring bottomside linear growth of the instability. The numerical simulation results are in good agreement with rocket and satellite in situ measurements and radar backscatter measurements, including some of the recent results from the August 1977 coordinated ground based measurement campaign conducted by DNA at Kwajalein.
Download or read book Nonlinear Equatorial Spread F written by S. T. Zalesak and published by . This book was released on 1980 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Motivated by the observations of large horizontal scale length equatorial spread F 'bubbles', we have performed numerical simulations of the nonlinear evolution of the collisional Rayleigh-Taylor instability in the nighttime equatorial ionosphere, using large horizontal scale length initial perturbations. The calculations were performed using a new, improved numerical code which utilizes the recently developed, fully multidimensional flux-corrected transport (FCT) techniques. We find that large horizontal scale initial perturbations evolve nonlinearly into equally large horizontal scale spread F bubbles, on a time scale as fast as that of the corresponding small horizontal scale length perturbations previously used. Further, we find the level of plasma depletion inside the large scale bubbles to be appreciably higher than that of the smaller scale bubbles, approaching 100%, in substantial agreement with the observations. This level of depletion is due to the fact that the plasma comprising the large scale bubbles has its origin at much lower altitudes than that comprising the smaller scale bubbles. Analysis of the polarization electric fields produced by the vertically aligned ionospheric irregularities show this effect to be due to fringe fields similar in structure to those produced at the edge of a parallel plate capacitor.
Download or read book Nonlinear Equatorial Spread F written by S. T. Zalesak and published by . This book was released on 1981 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aspects of the Linear and Nonlinear Development of Equatorial Spread F with Application to Ionospheric Scintillation written by Emanoel Paiva de Oliveira Costa and published by . This book was released on 1978 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonlinear Equatorial Spread F written by S. T. Zalesak and published by . This book was released on 1981 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: A simple model of the interaction of the equatorial ionosphere with the eastward F region neutral wind in the presence of evolving spread F bubbles or plumes is given. A consequence of the model is that the upper portions of plumes will take on a westward tilt, while the lower portions will tilt eastward, giving rise to the 'fishtails' and 'C's' observed by coherent backscatter radar measurements of field aligned small scale irregularities. The essence of the model is that the plasma away from the equatorial plane (e.g., a background nighttime E region at higher latitudes) makes a finite contribution to the magnetic field line integrated Pedersen conductivity, causing an incomplete coupling of the plasma motion to the neutral wind. The degree of coupling is then a function of the Pedersen conductivities both near the equator in the F region and in the higher latitude E region, giving rise to vertical shears of east-west plasma motion having opposing signs on either side of the equatorial Pedersen conductivity maximum. Evolving spread F plumes are caught up in this shear as they rise vertically, resulting in the characteristic 'C' shape seen by backscatter radar, and in the westward motion of plasma bubbles observed by satellite in situ measurements. Numerical simulations, incorporating an eastward neutral wind in the equatorial F region and E region Pedersen conductivity effects, are presented to further support the model and analysis. These simulations also show the result that it may be the eastward as well as the westward wall of the plume which is subject to secondary instabilities in the presence of an eastward neutral wind.
Download or read book Nonlinear Theory and Experimental Observations of the Local Collisional Rayleigh Taylor Instability in a Descending Equatorial Spread F Ionosphere written by M. J. Keskinen and published by . This book was released on 1981 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nonlinear evolution of the local collisional Rayleigh-Taylor instability in downward-moving equatorial F layers has been studied in a coordinated theoretical and experimental program dealing with actual conditions of bottomside spread F. For ambient bottomside electron density gradient scale lengths L=8 and 25 km, we find large percentage depletions and inverse power law spatial power spectra over the intermediate wavelength range wavelength=25 m-1 km. In addition we outline a nonlinear theory of the collisional Rayleigh-Taylor instability applicable to an upward or downward moving equatorial F region ionosphere. These results represent the first definitive comparison between experiment and theory with their agreement lending further support to the belief that the collisional Rayleigh-Taylor instability is responsible for large scale size irregularities that occure under conditions of equatorial spread F.
Download or read book Space Physics and Aeronomy Ionosphere Dynamics and Applications written by Chao Huang and published by John Wiley & Sons. This book was released on 2021-05-11 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive review of global ionospheric research from the polar caps to equatorial regions It's more than a century since scientists first identified the ionosphere, the layer of the Earth’s upper atmosphere that is ionized by solar and cosmic radiation. Our understanding of this dynamic part of the near-Earth space environment has greatly advanced in recent years thanks to new observational technologies, improved numerical models, and powerful computing capabilities. Ionosphere Dynamics and Applications provides a comprehensive overview of historic developments, recent advances, and future directions in ionospheric research. Volume highlights include: Behavior of the ionosphere in different regions from the poles to the equator Distinct characteristics of the high-, mid-, and low-latitude ionosphere Observational results from ground- and space-based instruments Ionospheric impacts on radio signals and satellite operations How earthquakes and tsunamis on Earth cause disturbances in the ionosphere The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals. Find out more about the Space Physics and Aeronomy collection in this Q&A with the Editors in Chief
Download or read book A Nonlinear Model for Equatorial Spread F Irregularity and Scintillation Calculations written by B. E. McDonald and published by . This book was released on 1976 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is shown, that a simple nonlinear model based upon plasma equations of motion and a wave equation for radio propagation is capable of predicting plasma irregularities and scintillations at the equator. The irregularities develop from a linear convective instability on the bottom of the F layer. Depleted regions, or bubbles, form and rise nonlinearly through the F peak, disturbing the top of the F layer. The equations of motion are integrated numerically, and then the parabolic equation is solved for propagation of a 300 MHz wave through the plasma. It is assumed that a modest total electron content of 5 x 10 to the 16th Power M( -2). From the radio wave solution scintillation indices are extracted as a function of time. Approximately two hours after the instability starts, S4 reaches 0.48, and the log power variance reaches 3.1 dB.
Download or read book A Review of Recent Results on Spread F Theory written by S. L. Ossakow and published by . This book was released on 1979 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although ionospheric Spread F was discovered four decades ago, only in the past few years has significant progress been made in the theoretical explanation of such phenomena. In particular, considerable effort has been expended to explain equatorial Spread F and the attendant satellite signal propagation scintillation phenomena. The present review dwells mainly in this low latitude area. The various linear plasma instabilities thought to initiate equatorial Spread F are discussed. Recent theoretical and numerical simulation studies of the nonlinear evolution of the collisional Rayleigh-Taylor instability in equatorial Spread F is reviewed. Analytical studies of rising equatorial Spread F bubbles in the collisional and collisionless Rayleigh-Taylor regime are discussed, as well as the nonlinear saturation of instabilities in these two regimes. Current theories on very small scale (approximately
Download or read book Aeronomy of the Earth s Atmosphere and Ionosphere written by Mangalathayil Ali Abdu and published by Springer Science & Business Media. This book was released on 2011-02-26 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a multi-author treatise on the most outstanding research problems in the field of the aeronomy of the Earth’s atmosphere and ionosphere, encompassing the science covered by Division II of the International Association of Geomagnetism and Aeronomy (IAGA). It contains several review articles and detailed papers by leading scientists in the field. The book is organized in five parts: 1) Mesosphere-Lower Thermosphere Dynamics and Chemistry; 2) Vertical Coupling by Upward Propagating Waves; 3) Ionospheric Electrodynamics and Structuring; 4) Thermosphere- Ionosphere Coupling, Dynamics and Trends and 5) Ionosphere-Thermosphere Disturbances and Modeling. The book consolidates the progress achieved in the field in recent years and it serves as a useful reference for graduate students as well as experienced researchers.
Download or read book Linear Theory of Equatorial Spread F written by David Arthur Russell and published by . This book was released on 1978 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Hierarchy of Processes Contributing to Equatorial Spread F written by David Lee Hysell and published by . This book was released on 1992 with total page 846 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Space Environment Research written by I.H. Cairns and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 535 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Space Environment Research - Volume I contains the proceedings of two international workshops, the World Space Environment Forum (WSEF2002) and the High Performance Computing in Space Environment Research (HPC2002), organized by the World Institute for Space Environment Research (WISER) from 22 July to 2 August 2002 in Adelaide, Australia. The articles in this volume review the state-of-the-art of the theoretical, computational and observational studies of the physical processes of Sun-Earth connections and Space Environment. They cover six topical areas: Sun/Heliosphere, Magnetosphere/Bow Shock, Ionosphere/Atmosphere, Space Weather/Space Climate, Space Plasma Physics/Astrophysics, and Complex/Intelligent Systems.
Download or read book Equatorial Spread F written by Wynne Calvert and published by . This book was released on 1962 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulations of Equatorial Spread F Using ALTAIR Incoherent Backscatter Measured Electron Density Profiles From the 17 July 1979 DNA Kwajalein Campaign written by S. T. Zalesak and published by . This book was released on 1980 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using electron density profiles measured by the ALTAIR radar on 17 July 1979, we have performed global large scale size numerical simulations of the nonlinear evolution of the collisional Rayleigh-Taylor instability in the equatorial ionosphere. The ALTAIR profiles were taken approximately four and one-half hours prior to the onset of equatorial spread F. Using 5% amplitude sinusoidal initial perturbations in our numerical simulations, we find fully developed spread F bubbles (plumes) on time scales of approximately one-half hour for both small (8 km) and large (200 km) horizontal scale lengths. (Author).
Download or read book The Earth s Ionosphere written by Michael Kelly and published by Elsevier. This book was released on 2012-12-02 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Earth's Ionosphere: Plasma Physics and Electrodynamics emphasizes the study of plasma physics and electrodynamics of the ionosphere, including many aeronomical influences. The ionosphere is somewhat of a battleground between the earth's neutral atmosphere and the sun's fully ionized atmosphere, in which the earth is embedded. One of the challenges of ionosphere research is to know enough about these two vast fields of research to make sense out of ionospheric phenomena. This book provides insights into how these competing sources of mass, momentum, and energy compete for control of the ionosphere. Some of the topics discussed include the fundamentals of ionospheric plasma dynamics; equatorial plasma instabilities; high-latitude electrodynamics; and instabilities and structure in the high-latitude ionosphere. Throughout this text only the region above 90 km are discussed, ignoring the D region entirely. This publication is a good source of information for students and individuals conducting research on earth's ionosphere.
Download or read book Linear Theory of Equatorial Spread F written by Mary K. Hudson and published by . This book was released on 1974 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt:
