Ionospheric Sporadic-E Parameters: Long-Term Trends

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Science  24 Aug 1984:
Vol. 225, Issue 4664, pp. 830-833
DOI: 10.1126/science.225.4664.830


The results of observations over 3½ solar cycles of ionosonde parameters describing sporadic-E patches (Es) are given for two Southern Hemisphere stations. Analysis has revealed systematic changes in the occurrence probabilities of foEs and fbEs, changes that are independent of time of day or season. It is unlikely that observational effects can be entirely responsible for the trends, which suggest that major long-term changes may be occurring at E region heights.