Solar-terrestrial disturbances of June - September 1982. IV. Ionospheric disturbances. X. Propagation disturbances of HF radio waves for long-distance circuits.
This paper describes the propagation condition of short waves observed at Hiraiso by fixed- and swept-frequencies during sudden ionospheric disturbances and ionospheric storms which occurred between June and September 1982. It is shown on the basis of oblique ionograms measured by an FM-CW oblique-incidence ionosonde that a usable frequency bandwidth between maximum usable frequency and lowest usable frequency became narrower due to an increase in absorption along the path with an occurrence of sudden ionospheric disturbance. A geomagnetic disturbance under some seasonal and time conditions made some interesting phenomena in propagation condition for the north-south path. This exceptional propagation condition for the north-south path is briefly discussed.
Radio Research Laboratory, Journal
- Pub Date:
- Solar-Terrestrial Relations