VLF PHASE DISTURBANCES, HF ABSORPTION, AND SOLAR PROTONS IN THE EVENTS OF AUGUST 28 AND SEPTEMBER 2, 1966.

The VLF phase disturbances and HF absorption observed during the proton events of August 28 and September 2, 1966, were quantitatively connected to the proton intensities, energies, and cutoff latitudes observed by satellite 1963-38C, at 1100 km in a polar orbit. The connection is achieved through considerations that include a model of the ionospheric D region described in terms of an effective recombination coefficient related to the four generalized ionic reactions. The complementary use of the VLF and HF observations tends to reduce ambiguities often present in the formation of D-region models. The VLF is the more sensitive indicator of ionization effects due to solar protons in comparison to the HF absorption (especially at night) because the VLF responds to ionization enhancements over a relatively narrow altitude range varying with the proton energies and intensities.

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