Abstract
The Faraday rotation angle of a linearly polarized transionospheric very high frequency (VHF) signal near the crests of the Appleton anomaly, around the recent solar maximum period, often exhibits fast and intense fluctuations, when the amplitude of the signal shows saturated and very fast scintillations1,2. These fluctuations usually occur during the post-sunset hours and decay around midnight. The occurrence pattern has been found to be similar to that of microwave amplitude scintillations at L-band. We present here certain observed characteristics of the fast polarization fluctuations and report the results of an experiment, which shows that there is a loss of correlation between fadings on the two circularly polarized component modes of the signal during the periods of VHF polarization fluctuations. Hence, the usual concept of Faraday rotation is no longer valid during these times. The above features are discussed in terms of our present knowledge of small scale irregularity structures in the equatorial ionosphere.
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DasGupta, A., Lee, M. & Klobuchar, J. VHF Faraday polarization fluctuations and strong L-band amplitude scintillations near Appleton anomaly crests. Nature 298, 354–357 (1982). https://doi.org/10.1038/298354a0
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DOI: https://doi.org/10.1038/298354a0
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