Influence of the semidiurnal lunar tide in the equatorial plasma bubble zonal drifts over Brazil
<p>Using OI6300 airglow images collected over São João do Cariri (7.4<span class="inline-formula"><sup>∘</sup></span> S, 36.5<span class="inline-formula"><sup>∘</sup></span> W) from 2000 to 2007, the equatorial plasma bubble (...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-12-01
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| Series: | Annales Geophysicae |
| Online Access: | https://angeo.copernicus.org/articles/39/1005/2021/angeo-39-1005-2021.pdf |
| Summary: | <p>Using OI6300 airglow images collected over São João do Cariri (7.4<span class="inline-formula"><sup>∘</sup></span> S, 36.5<span class="inline-formula"><sup>∘</sup></span> W) from 2000 to 2007, the equatorial plasma bubble (EPB) zonal drifts were calculated. A strong day-to-day variability was observed in the EPB zonal drifts, which is directly associated with the very complex dynamics of the nighttime thermosphere–ionosphere system near the Equator. The present work investigated the contribution of the semidiurnal lunar tide <span class="inline-formula"><i>M</i><sub>2</sub></span> for the EPB zonal drifts. The <span class="inline-formula"><i>M</i><sub>2</sub></span> presented an amplitude of 3.1 m s<span class="inline-formula"><sup>−1</sup></span> in the EPB zonal drifts, which corresponds to 5.6 % of the average drifts. The results showed that the <span class="inline-formula"><i>M</i><sub>2</sub></span> amplitudes in the EPB zonal drifts were solar cycle and seasonally dependent. The amplitude of the <span class="inline-formula"><i>M</i><sub>2</sub></span> was stronger during the high solar activity, reaching over 10 % of the EPB zonal drift average. Regarding the seasons, during the Southern Hemisphere summer, the <span class="inline-formula"><i>M</i><sub>2</sub></span> amplitude was twice as large (12 %) compared to the equinox ones. The seasonality agrees with other observations of the <span class="inline-formula"><i>M</i><sub>2</sub></span> in the ionospheric parameters such as vertical drifts and electron concentration, for instance. On the other hand, the very large <span class="inline-formula"><i>M</i><sub>2</sub></span> amplitudes found during the high solar activity agree with previous observations of the lunar tide in the ionospheric E region.</p> |
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| ISSN: | 0992-7689 1432-0576 |