Comparative Equatorial Scintillation Morphology--American and Pacific Sectors.
Topical rept. no. 3, 1 Jun 77-30 Jun 78,
SRI INTERNATIONAL MENLO PARK CA
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This report examines the severity of radio-wave amplitude scintillation measured at two stations near the equator, but far apart in longitude Kwajalein Atoll in the Marshall Islands, and Ancon, Peru. The data used are observations of the Wideband satellite signal intensity at VHF, UHF, and L-band frequencies. These are presented in terms of the cumulative distribution of S4 index, which provides a precise measure of the level of disturbance that can be readily related to the distribution of signal intensity. The seasonal behavior of the scintillation at the two stations is similar, with each showing a broad 8-to-9-month disturbed season centered about local summer. There is little difference in the occurrence or severity of gigahertz scintillation at the two stations. However, there is a systematic difference between the frequency dependences of the scintillation. The latitude distributions of scintillation show the expected enhancement from propagation geometry at low elevation angles. When these effects are removed to obtain irregularity source strength, the irregularity source regions are found at some distance from the magnetic equator. It is suggested that the weak-to-moderate scintillation that dominates the observations arises from interactions between neutral waves and ionization in the F region.
- Atmospheric Physics
- Radiofrequency Wave Propagation
- Radio Communications