Studies Of Solar Flare Effects And Other Ionospheric Disturbances With A High Frequency Doppler Technique

This report presents some results of work done with a Doppler technique for studying ionospheric disturbances. The theoretical results include a calculation of the frequency shifts to be expected from ch * anges in the parameters of a parabolic model iono.

This report contains a review of the work done on frequency fluctuations of ionospheric radio echoes on high frequencies. The historical aspects are briefly discussed to show the development of research on solar flare effects and the motion of ionospheric irregularities. The recording program over the past 7 years and the equipment modifications involved are discussed. This is followed by a brief review of the elementary theory underlying frequency fluctuations. In most of the report the mathematical equations are listed in tables rather than distributed throughout the text. Solar flare effects (called sudden frequency deviations) are used to determine the relaxation time of the ionosphere.

This report describes a radio investigation of traveling ionospheric disturbances carried out near Boulder, Colorado, over a 1-year period from June 1967 to June 1968. The three-dimensional motions of F2 layer disturbances were measured by the high frequency Doppler technique with spaced transmitters and at several probing frequencies. Horizontal motions were determined by cross-correlating three signals on frequencies near 5 MHz, whose reflection points were approximately at the corners of a horizontal equilateral triangle with 40-km sides. Vertical motions were determined from cross-correlation of signals on frequencies of 3.3, 4.0, and 5.1 MHz, whose reflection points were aligned vertically.