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Proceedings with Extended Abstracts (single PDF file) - Radio ...

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similar correlation <strong>with</strong> larger magnitudes at negative SOI above altitude 85 km [seeGavrilov et al., 2003b].100v' 2 , m 2 /s 210092 km100v' 2 ,m 2 /s 210092 kmu' 2 , m 2 /s 2 -10000u' 2 ,m 2 /s 2 -10000-100505088 km-100505088 km0000-50-50-50-5050050084 km50050084 km-50-50-50-50505080 km505080 km0000-50-50-50-50505076 km505076 km0000-50-50-40 -20 0 20 SOI -40 -20 0 20 SOIa)-50-50-40 -20 0 20 SOI -40 -20 0 20 SOIb)Fig. 4. Dependence of deviations from average monthly values on Southern OscillationIndex for WH variance in winter (a) and summer (b) for zonal (left plots) and meridional(right plots) components .3. Analysis of nightglow variations.IGWs in the middle and upper atmosphere may produce variations of intensity androtation temperature of nigh airglows, which are widely used for studies of waves in themiddle and upper atmosphere. A method of the analysis of IGW parameters fromobservations of variations of night airglows was developed in St. Petersburg University[Gavrilov et al., 2002]. The method is based on the analysis of simultaneous observationsof variations of intensity and rotation temperature of night airglows measured by scanningspectral devices simultaneously in several points of the sky. The algorithm includespreliminary quality check of experimental data, low and a high-frequency filtering andspectral analysis of variations of characteristics of night airglows in each point at the sky,and also definition of parameters of spectral components.This method was applied for the analysis of results of long-term observations of wavevariations of night airglows of hydroxyl (OH) and molecular oxygen (O 2 ) at altitudesaround 87 and 94 km, respectively, using optical device SATI, which were carried out inShigaraki, Japan (35º N, 136º E) since October 1998. Duration of continuous intervals ofnight measurements varies from 2 up to 12 hours, and the data sampling is about 2minutes.For studying seasonal changes of statistical characteristics, all data are divided intofour groups: winter (from November to February), summer (May – August), spring andautumn (months between mentioned above). Full numbers of clear moonless nights ofobservation for these seasons are of 82, 27, 15 and 16, respectively. In Figure 5, polarhistograms of azimuths of IGW propagation in layers of OH and O 2 airglows are shown.Some dominance of northwest and southern directions for OH emission, and northwestand southeast sectors for O 2 emission in winter is observed. In summer, IGWs propagate,basically, to northern hemisphere. In spring, distribution of IGW azimuths in Figure 5 issimilar to the summer one, and in autumn IGW azimuths have more wide distributionsbasically into northern hemisphere. Analysis reveals maxima of variations of intensityand rotation temperature of nightglow emissions in November - December and theirdecreasing in September – October [see Gavrilov et al., 2002].171

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