Study of ELF Propagation Anomalies as Related to Improved Knowledge of Electron Density Profiles Produced by Energetic Particle Precipitation.
Abstract
A study has been made of extremely low frequency (ELF) wave propagation anomalies as related to energetic particle precipitation, principally during solar particle events (SPE). Based on calculation of the predicted signal strengths at Tromso for transmissions from the Wisconsin Test Facility (WTF) a criterion has been selected for possible use in a field test operation. If the ion pair production rates at 40 km are equal to or greater than 1 x 1000/cc/sec then it is probable that a 3 dB or larger reduction in signal strength would occur for such an event. Since this preliminary criterion is based on ELF signal strength computation assuming no local time variations along the propagation path, more detailed calculations of the local time ionospheric effects should be performed. A study was made of the expected effect of local time variations during solar particle events on the ELF propagation over the path from WTF to Tromso. Electron and ion density profiles for the various segments of the test path were calculated with the ion chemistry model, taking into account the local time for each segment. In a comparison of conditions measured and calculated for SPE72 on 4 August 1972 near the peak of the event and conditions measured and calculated for a similar case assuming a season of 21 December, very little difference in signal strength attenuation over the path was found.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 30, 1980
- Accession Number
- ADA087255
Entities
People
- Edward E. Gaines
- Joseph B. Reagan
- Robert C. Gunton
- Trygve R. Larsen
- William L. Imhof
Organizations
- Lockheed Martin Missiles and Space