Volumes and Issues  Contents of Issue 12

Ann. Geophys., 24, 3343-3350, 2006
www.ann-geophys.net/24/3343/2006/
© European Geosciences Union 2006

Signatures of 3–6 day planetary waves in the equatorial mesosphere and ionosphere

H. Takahashi¹, C. M. Wrasse¹, D. Pancheva², M. A. Abdu¹, I. S. Batista¹, L. M. Lima³, P. P. Batista¹, B. R. Clemesha¹, and K. Shiokawa^4
1Instituto Nacional de Pesquisas Espaciais, INPE, CP-515, 12245-970 São José dos Campos, SP, Brazil
²Department of Electronic & Electrical Engineering, University of Bath, Bath, BA2 7AY, UK
³Dept. Física, Universidade Estadual de Paraíba, Campina Grande, PB, Brazil
⁴Solar Terrestrial Environmental Laboratory, STEL, Nagoya University, Toyokawa, Aichi 442-8507, Japan

Abstract. Common periodic oscillations have been observed in meteor radar measurements of the MLT winds at Cariri (7.4° S, 36.5° W) and Ascension Island (7.9° S, 14.4° W) and in the minimum ionospheric virtual height, h'F, measured at Fortaleza (3.9° S, 38.4° W) in 2004, all located in the near equatorial region. Wavelet analysis of these time series reveals that there are 3–4-day, 6–8-day and 12–16-day oscillations in the zonal winds and h'F. The 3–4 day oscillation appeared as a form of a wave packet from 7–17 August 2004. From the wave characteristics analyzed this might be a 3.5-day Ultra Fast Kelvin wave. The 6-day oscillation in the mesosphere was prominent during the period of August to November. In the ionosphere, however, it was apparent only in November. Spectral analysis suggests that this might be a 6.5-day wave previously identified. The 3.5-day and 6.5-day waves in the ionosphere could have important roles in the initiation of equatorial spread F (plasma bubble). These waves might modulate the post-sunset E×B uplifting of the base of the F-layer via the induced lower thermosphere zonal wind and/or the E-region conductivity.

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Citation: Takahashi, H., Wrasse, C. M., Pancheva, D., Abdu, M. A., Batista, I. S., Lima, L. M., Batista, P. P., Clemesha, B. R., and Shiokawa, K.: Signatures of 3–6 day planetary waves in the equatorial mesosphere and ionosphere, Ann. Geophys., 24, 3343-3350, 2006.   Bibtex   EndNote   Reference Manager