Observation of Large-Scale Traveling Ionospheric Disturbances by Spaced-Path, H-F, Instantaneous-Frequency Measurements
STANFORD UNIV CA STANFORD ELECTRONICS LABS
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The instantaneous frequency of WWV, 20mc, Wash., D. C., and a stable signal at 17.8 Mc Mayaguez, Puerto Rico were simultaneously recorded between Oct 1960 and Sep 1961 at Palo Alto, Calif., and Seattle, Wash. Traveling ionospheric disturbances were identified by noting the occurrence of similar frequency fluctuations appearing with appropriate time delays, and in appropriate order, on each of four available paths. The geometry of these paths is such that disturbances traveling from north to south, or vice-versa, are easily detected. The disturbances gave rise to either quasi-sinusoidal, or V- shaped fluctuations in recordings of frequency vs. time. If a given disturbance is assumed to travel along a great circle at constant speed, this speed can be estimated from the time interval between interception of the northernmost transmission path and the southernmost one. From the duration of the resulting fluctuation on a given path and the estimated speed of the disturbance, its effective spatial length can be inferred.
- Radiofrequency Wave Propagation