Variability in the maximum height of the ionospheric F2-layer over Millstone Hill (September 1998–March 2000); influence from below and above
The basic aim of this ‘case study’ is to investigate the variability in the maximum height of the ionospheric F2-layer, <i>hm</i>F2, with periods of planetary waves (2–30 days), and to make an attempt to determine their origin. The hourly data of <i>hm</i>F2 above Mil...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2002-11-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/20/1807/2002/angeo-20-1807-2002.pdf |
| Summary: | The basic aim of this ‘case
study’ is to investigate the variability in the maximum height of the
ionospheric F2-layer, <i>hm</i>F2, with periods of planetary waves (2–30
days), and to make an attempt to determine their origin. The hourly data of <i>hm</i>F2
above Millstone Hill (42.6° N, 71.5° W) during 01 September 1998 - 31 March
2000 were used for analysis. Three types of disturbances are studied in detail:
(i) the 27- day oscillations observed in the <i>hm</i>F2 above Millstone Hill
are generated by the geomagnetic activity and by the global-scale 27-day wave
present in the zonal mesosphere/lower thermosphere (MLT) neutral wind. The time
delay between the 27-day oscillation in the zonal wind and that in the <i>hm</i>F2
is found to be 5–6 days, while between the 27-day oscillation in the
geomagnetic activity and that in the <i>hm</i>F2 is found to be 0.8–1 day;
(ii) the 16-day oscillation in the <i>hm</i>F2 observed during summer 1999 is
probably generated by the global scale 16-day modulation of the semidiurnal
tide observed in the MLT region during PSMOS campaign in June–August. We
found that if the modulated semidiurnal tide mediates the planetary wave
signature in the ionosphere, this planetary wave oscillation has to be best
expressed in the amplitude and in the phase of the 12-h periodicity of the
ionosphere; and (iii) the third type of disturbances studied is the quasi-2-
day activity in the <i>hm</i>F2 that increases during geomagnetic disturbances.
The strong pseudo diurnal periodicities generated during the geomagnetic storms
can interact between each other and produce the quasi-2-day oscillations in the
ionosphere.<br><br><b>Key words. </b>Ionosphere (ionosphere-atmosphere
interactions; ionosphere-magnetoshpere interactions; wave propagation) |
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| ISSN: | 0992-7689 1432-0576 |