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Abstract

There is growing evidence for Alfven wave activity on low-latitude field lines, but the modeling of such waves, which necessarily interact with highly-collisional plasma, has received little attention. In this talk I will describe a fully electromagnetic and fully collisional calculation for low-latitude field lines, which finds that these field lines can resonate much more easily than expected, even at very low latitudes. Applications to E-F coupling and to 150 km echoes are included. Highly significant effects are found for electric field mapping, and for the loading of higher-altitude phenomena by E-region conductivity. A fully electromagnetic calculation is given for this loading conductance, which finds very significant deviations from the usual field line integrated conductivity. Even the local conductivity is altered, when it is recognized that the imaginary part of frequency should be included in the usual conductivity equations. All in all it is found that low-latitude field lines should be subject to a host of resonant phenomena that we are only beginning to probe. The discussion will revolve around a simple gedanken experiment.