The verage morphology of magnetic storms with sudden commencement was studied with 346 magn tic storms that occurred in the years 1902 to 1945. Magnetic recor from 26 observatories were used. The 346 storms were classed into three intensity groups of great, moderate and weak storms, and their morphology was investig ted s par t ly S OR VARI TION WAS ANALYZED INTO WO PARTS, Dst and DS. DS was naly ed harmonically, and its changes with storm time were studied in great detail. The author's present views on stor sudden commencements and on the b ormal nature of t e storm variations at the geomagnetic equator are briefly reviewed. (Author).

Sudden Ionospheric Disturbances resulting from an interaction of the Solar Flare radiation with the constituents of the upper atmosphere constitute one of the three major aspects of ground level monitoring of solar flares -the other two being optical observations of flares, and the observations of solar bursts in radio wavelengths. SIDs, therefore, form a major part of flare monitoring programme in many observatories. Unlike the other two, however, the ionospheric effects of flares provide one major additional source of interest - the reaction of the ionospheric plasma to an impulsive ionization. The high atmosphere provides a low pressure laboratory without walls in which a host of reactions occur between electrons, ions and neutral particles. The resulting products and their distributions may bear no resemblance to those of the primary neutral constituents or their direct ionization products. The variations with the time of the day, with season and with solar activity that form the bulk of the ionospheric measurements are too slow to allow any insight into the nature of these ionospheric reactions whose lifetimes are often very short. The relaxation time of the ionospheric ionization is only a few minutes or fraction of a minute in the lower ionosphere and in the E-region and is about 30 min to an hour at 300 km. The flares provide a sudden short impulse comparable to these time scales.

Physics of Geomagnetic phenomena, Volume I covers the significant advances in geomagnetism and the penetrations into the generation of geomagnetic field phenomena. This volume is composed of three chapters. Chapter I deals briefly with the discovery and developments in geomagnetism, followed by discussions on some fundamental topics of the field, including the aurora and geomagnetic storms. This chapter also considers the instruments, geomagnetic stations, and the correlations between geomagnetic indices. Chapter II describes the magnetic properties of minerals and various processes of acquisition of remanent magnetization. This chapter also provides palaeomagnetic data for the direction and intensity of the geomagnetic field in ancient times. Chapter III explores geomagnetic variations caused by solar flares and eclipses. This book will prove useful to physicists, students in upper atmospheric and space topics, and scientists in allied fields with a background in geomagnetism.

Documents the science, the mission, the spacecraft and the instrumentation on a unique NASA mission to study the Earth’s dynamic, dangerous and fascinating Van Allen radiation belts that surround the planet This collection of articles provides broad and detailed information about NASA’s Van Allen Probes (formerly known as the Radiation Belt Storm Probes) twin-spacecraft Earth-orbiting mission. The mission has the objective of achieving predictive understanding of the dynamic, intense, energetic, dangerous, and presently unpredictable belts of energetic particles that are magnetically trapped in Earth’s space environment above the atmosphere. It documents the science of the radiation belts and the societal benefits of achieving predictive understanding. Detailed information is provided about the Van Allen Probes mission design, the spacecraft, the science investigations, and the onboard instrumentation that must all work together to make unprecedented measurements within a most unforgiving environment, the core of Earth’s most intense radiation regions. This volume is aimed at graduate students and researchers active in space science, solar-terrestrial interactions and studies of the upper atmosphere. Originally published in Space Science Reviews, Vol. 179/1-4, 2013.

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