Numerical Model of the Equatorial Electrojet


Book Description

A computer program which calculates electron and ion densities, ionospheric conductivities, electric fields and currents, and magnetic variations in regions near the magnetic equator is described in detail. It is also explained how this numerical model can be used to deduce F-region vertical plasma drifts in the equatorial ionosphere from observed magnetic variations at ground level. (Author).




Equatorial Electrojet


Book Description

This is the first book to review all the fields of equatorial electrojet phenomena and their relevant theories in one volume. In certain relevant sections, the book discusses both the equatorial electrojet and the world-wide parts of the Sq current systems. Onwumwchili is an internationally known and highly respected expert in the equatorial electrojet field- a brand of geomagnetism.




Magnetic Fields in the Solar System


Book Description

This book addresses and reviews many of the still little understood questions related to the processes underlying planetary magnetic fields and their interaction with the solar wind. With focus on research carried out within the German Priority Program ”PlanetMag”, it also provides an overview of the most recent research in the field. Magnetic fields play an important role in making a planet habitable by protecting the environment from the solar wind. Without the geomagnetic field, for example, life on Earth as we know it would not be possible. And results from recent space missions to Mars and Venus strongly indicate that planetary magnetic fields play a vital role in preventing atmospheric erosion by the solar wind. However, very little is known about the underlying interaction between the solar wind and a planet’s magnetic field. The book takes a synergistic interdisciplinary approach that combines newly developed tools for data acquisition and analysis, computer simulations of planetary interiors and dynamos, models of solar wind interaction, measurement of ancient terrestrial rocks and meteorites, and laboratory investigations.










The Equatorial Electrojet


Book Description

This dissertation describes a theoretical, experimental, and modeling investigation of the equatorial electrojet. We review low latitude ionospheric current models, synthesizing developments from the early times until the present. We then show how to utilize equatorial electrojet irregularities to infer E region electron density and wind profiles from coherent scatter radar experiments. The procedure involves a numerical model of the equatorial ionosphere that relates the vector electric field and current density to the winds. We present electron densities inferred in the equatorial electrojet inferred using a new bistatic radar system installed between Paracas and Jicamarca, Peru. The radar system monitors density profiles using a coherent scatter radar technique that utilizes the Faraday rotation of the scattered signal. Radar measured density profiles are validated by comparing with other electron density measures. A three dimensional electrostatic potential model of the equatorial ionosphere in a magnetic dipole coordinate system is described. The model incorporates realistic ionospheric conductivities, electric fields, winds, and includes anamalous collision effects. The model utilizes bistatic radar measured densities, coherent scatter spectral measurements made at large zenith angles, and electric fields derived from 150 km echo drifts. The model is also constrained by magnetometer records. We next present a technique for extracting zonal winds in the equatorial electrojet from the Doppler shifts of type II radar echoes measured by a narrow beam, obliquely oriented antenna at the Jicamarca Radio Observatory. The wind profiles were retrieved by combining the 3-D model with theory and measurements of type II echo Doppler shifts. The amplitude and phasing of the calculated wind profiles are in general agreement with satellite and rocket-borne wind measurements. We have used height varying type I radar echoes and large-scale electrojet irregularities inferred from interferometric imaging to validate wind profiles estimates derived from type II echoes. (Abstract).










Quiet Daily Geomagnetic Fields


Book Description

Reprint from Pure and Applied Geophysics (PAGEOPH), Volume 131 (1989), No. 3




Ionospheric Space Weather


Book Description

This monograph is the outcome of an American Geophysical Union Chapman Conference on longitude and hemispheric dependence of ionospheric space weather, including the impact of waves propagating from the lower atmosphere. The Chapman Conference was held in Africa as a means of focusing attention on an extensive geographic region where observations are critically needed to address some of the fundamental questions of the physical processes driving the ionosphere locally and globally. The compilation of papers from the conference describes the physics of this system and the mechanisms that control ionospheric space weather in a combination of tutorial-like and focused articles that will be of value to the upper atmosphere scientific community in general and to ongoing global magnetosphere-ionosphere-thermosphere (MIT) modeling efforts in particular. A number of articles from each science theme describe details of the physics behind each phenomenon that help to solve the complexity of the MIT system. Because this volume is an outcome of the research presented at this first space science Chapman Conference held in Africa, it has further provided an opportunity for African scientists to communicate their research results with the international community. In addition, the meeting and this conference volume will greatly enhance the space science education and research interest in the African continent and around the world. Ionospheric Space Weather includes articles from six science themes that were discussed at the Chapman Conference in 2012. These include: Hemispherical dependence of magnetospheric energy injection and the thermosphere-ionosphere response Longitude and hemispheric dependence of storm-enhanced densities (SED) Response of the thermosphere and ionosphere to variability in solar radiation Longitude spatial structure in total electron content and electrodynamics Temporal response to lower-atmosphere disturbances Ionospheric irregularities and scintillation Ionospheric Space Weather: Longitude Dependence and Lower Atmosphere Forcing will be useful to both active researchers and advanced graduate students in the field of physics, geophysics, and engineering, especially those who are keen to acquire a global understanding of ionospheric phenomena, including observational information from all longitude sectors across the globe.