Passive remote sensing of the Earth's plasmasphere using Whistler mode waves

As the uses of artificial satellites diversify, investigation of the propagation characteristics of electric waves surrounding the Earth has become an important task. These electric waves are strongly influenced by plasma, a propagation medium, but although on the one hand investigation of plasma in the ionosphere is proceeding with various different methods being used, current investigations into the density profile of plasma in the plasmasphere is not progressing since it is hampered by the fact that satellites produce only single point observations. In this paper we develop a method for estimating the density profile of the global electrical field of the plasmasphere from natural VLF band electromagnetic wave frequency spectra and propagation vector direction information observed by satellite by solving an ill-posed inverse problem. We confirm the uniqueness of the solution by performing a brute force search using a dictionary and investigate the applicability of our method to actual data by using pseudo-observation data. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 51–61, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20377