In the auroral lower-E and upper-D region of the ionosphere, plasma clouds,such as sporadic-E layers and meteor plasma trails, occur daily. Large-scaleelectric fields, created by the magnetospheric dynamo, will polarize thesehighly conducting clouds, redistributing the electrostatic potential andgenerating anisotropic currents both within and around the cloud. Using asimplified model of the cloud and the background ionosphere, we develop thefirst self-consistent three-dimensional analytical theory of these phenomena.For dense clouds, this theory predicts highly amplified electric fieldsaround the cloud, along with strong currents collected from the ionosphereand circulated through the cloud. This has implications for the generation ofplasma instabilities, electron heating, and global MHD modeling ofmagnetosphere-ionosphere coupling via modifications of conductances inducedby sporadic-E clouds.
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