Persistence of planetary wave type oscillations in the mid-latitude ionosphere

J. Lastovicka, P. Sauli, P. Krizan

Abstract


Planetary wave type oscillations have been observed in the lower and middle atmosphere but also in the ionosphere,
including the ionospheric F2 layer. Here we deal with the oscillations in foF2 analysed for two Japanese
and two US stations over a solar cycle (1979-1989) with the use of the Morlet and Paul wavelet transforms.
Waves with periods near 5, 10 and 16 days are studied. Only events of duration of three wave-cycles and more
are considered. The results are compared with the results of a similar analysis made for foF2 and the lower ionosphere
over Europe (Las?tovic?ka et al., 2003a,b). The 5-day period wave events display a typical duration of 4
cycles, while the 10- and 16-day wave events are less persistent with typical duration of about 3.5 cycles and
rather 3 cycles, respectively, in all three geographic regions. The persistence pattern in terms of number of cycles
and in terms of number of days is different. In terms of number of cycles, the typical persistence of oscillations
decreases with increasing period. On the other hand, in terms of number of days the typical persistence evidently
increases with increasing period. The spectral distribution of event duration is too broad to allow for a
reasonable prediction of event duration. Thus the predictability of the planetary wave type oscillations in foF2
seems to be very questionable. The longitudinal size of the planetary wave type events increases with increasing
wave period. The persistence of the planetary wave type events in foF2 and the lower ionosphere is similar in
Europe, but the similarity in occurrence of individual events in foF2 and the lower ionosphere is rather poor.

Keywords


ionosphere;atmosphere interaction;mid-latitude ionosphere;ionospheric disturbances;atmospheric waves

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References


DOI: https://doi.org/10.4401/ag-3098
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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X