Frequency and duration of disturbances in the mid-latitude F region of the ionosphere
Disturbances of the ionospheric F region at two well-separated midlatitude stations were identified on rapid run ionograms by spread echoes, blackouts, and anomalies in structure or critical frequency. The diurnal variation in the probability of disturbance consistently shows minima around sunrise and sunset. Details such as a brief postsunset enhancement in winter are revealed by the fine time resolution of the data. Disturbance probabilities were lowest in autumn and spring (8 and 9 percent), while that for winter (33 percent) exceeded the summer level (20 percent). Spread F constituted 32 percent of the events, and disturbances producing sharply defined ionogram signatures 77 percent, with some overlapping of types. The majority of disturbances were not correlated with geomagnetic phenomena. Disturbances at the two stations were essentially independent (spatial correlation of 0.15). Spread F events were of longer duration (25 min) than sharp disturbances (20 min). 24 references.
- Research Organization:
- Council for Scientific and Industrial Research, Pretoria (Republic of South Africa)
- OSTI ID:
- 6593758
- Journal Information:
- Radio Sci.; (United States), Vol. 23
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
F REGION
DISTURBANCES
DAILY VARIATIONS
IONOSONDES
SEASONAL VARIATIONS
SEASONS
EARTH ATMOSPHERE
ELECTRONIC EQUIPMENT
EQUIPMENT
IONOSPHERE
PLANETARY IONOSPHERES
RADIO EQUIPMENT
VARIATIONS
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena