A Comparative Analysis of Equatorial Spread F and VHF Scintillation

Abstract : This report describes a series of simultaneous high-resolution ionosonde and VHF scintillation measurements made a Kwajalein during August 1981, a period of intense equatorial spread-F. The scintillation data were processed to measure the Doppler spread, which was found to be closely correlated with a recurrent ionogram pattern of oblique echoes, h'F variations, and range spread. The ionogram patterns are evidently due to the overhead passage of bottomside F-region upwellings. The combined measurements provide a comparatively simple means of monitoring spread-F activity. The report also reviews five years of summertime ionosonde measurements made at Kwajalein that show dramatic ionospheric changes with increasing solar cycle activity. The results are discussed in light of global occurrence patterns and the behavior of polarization fields at the equator.

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