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Sauli, P.
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Sauli, P.
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- PublicationOpen AccessPersistence of planetary wave type oscillations in the mid-latitude ionosphere(2006-12)
; ; ; ;Lastovicka, J.; Institute of Atmospheric Physics, Academy of Sciences of Czech Republic, Prague, Czech Republic ;Sauli, P.; Institute of Atmospheric Physics, Academy of Sciences of Czech Republic, Prague, Czech Republic ;Krizan, P.; Institute of Atmospheric Physics, Academy of Sciences of Czech Republic, Prague, Czech Republic; ; 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 (Lasˇtovicˇka 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.155 261 - PublicationOpen AccessPlanetary and gravity wave signatures in the F-region ionosphere with impacton radio propagation predictionsand variability(2004)
; ; ; ; ; ;Altadill, D.; Observatorio del Ebro (URL-CSIC), Roquetes, Spain ;Apostolov, E. M.; Geophysical Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria ;Boska, J.; Institute of Atmospheric Physics, Academy of Sciences of Czech Republic, Prague, Czech Republic ;Lastovicka, J.; Institute of Atmospheric Physics, Academy of Sciences of Czech Republic, Prague, Czech Republic ;Sauli, P.; Institute of Atmospheric Physics, Academy of Sciences of Czech Republic, Prague, Czech Republic; ; ; ; The aim of this work within the WP 3.1 of the COST 271 Action is the characterization of the variability introduced in the F-region ionosphere by -Planetary Wave Signatures- (PWS) and -Gravity Wave Signatures- (GWS). Typical patterns of percentage of time occurrence and time duration of PWS, their climatology and main drivers, as well as their vertical and longitudinal structure have been obtained. Despite the above characterization, the spectral distribution of event duration is too broad to allow for a reasonable prediction of PWS from ionospheric measurements themselves. GWS with a regular morning/evening wave bursts and specific GWS events whose arising can be predicted have been evaluated. As above, their typical pattern of occurrence and time duration, and their vertical structure have been obtained. The latter events remain in the ionospheric variability during disturbed days while additional wave enhancements of auroral origin occur. However, both types of disturbances can be distinguished.223 431