Development of Models of Electron Density in the Magnetosphere from Ground and Satellite-Based Radio Data

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The purpose of this grant is for the development and interpretation of empirical models of electron density in the equatorial plane of the earth's magnetosphere. When available, these models will provide a substantially improved basis for studies of magnetospheric convection, wave-particle interactions, and plasma interchange between the magnetosphere and ionosphere. The models would be based primarily upon a combination of results from whistlers recorded be Stanford University at Antarctic stations and from the University of Iowa Plasma Wave Experiment Sweep Frequency Receiver on the ISEE-1 satellite. Magnetospheric research has reached a point of increasing emphasis upon the development of theoretical and empirical models of the plasma distribution and dynamics, an example of this emphasis being the October 1986 Huntsville Workshop on Magnetosphere-Ionosphere Plasma Models. Among the magnetospheric plasma parameters which one can model empirically, equatorial electron density neq now appears to be one of the most important and most accessible. This parameter is of scientific interest for many reasons. It depends upon a number of fundamental physical processes that are difficult to observe, such as solar wind induced convection and relate substorm morphology and the interchange of ionization with the spatially and temporally variable ionosphere. neq represents the equatorial propagation medium and hence the conditions on wave refractive index under which resonant wave particle interactions take place, including particle scattering from the radiation belts. The equatorial plasma is also an important part of the medium through which ULF waves must propagate in carrying energy form either the solar wind or the magnetopause regions where wave-particle interactions may be modulated at ULF frequencies.