Bottom‐type spread F events were observed in the south American equatorial region by a VHF coherent radar and an ionosonde at São Luís (2.5°S, 44.3°W), an ionosonde at Fortaleza (3.9°S, 38.4° W) and an airglow OI 630.0 nm imager at Cariri (7.4°S, 36.5°W) and Brasilia (14.8°S, 47.6°W). In the evening of September 30, 2005, a long duration (∼70 minutes) bottom side scattering layer, confined in a narrow height region, was observed. At the same time all‐sky imager observed sinusoidal intensity depletions in the zonal plane extending more than 1500 km and elongated along the magnetic meridian. No strong spread F structures developed during the period. Subsequently well developed plasma bubbles were observed. This suggests that the observed bottom‐type spread F is an initial phase of the plasma bubbles. We report, for the first time, longitudinal and latitudinal extension of the bottom‐type spread F as diagnosed by optical imagers.

During the Spread F Experiment campaign, under NASA Living with a Star (LWS) program, carried out in the South American Magnetic Equator region from 22 September to 8 November 2005, two airglow CCD imagers, located at Cariri (7.4° S, 36.5° W, geomag. 11° S) and near Brasilia (14.8° S, 47.6° W, geomag. 10° S) were operated simultaneously and measured the equatorial ionospheric bubbles and their time evolution by monitoring the airglow OI 6300 intensity depletions. Simultaneous observation of the mesospheric OH wave structures made it possible to investigate the relationship between the bubble formation in the ionosphere and the gravity wave activity at around 90 km. On the evening of 30 September 2005, comb-like OI 6300 depletions with a distance of ~130 km between the adjacent ones were observed. During the same period, a mesospheric gravity wave with a horizontal wavelength of ~130 km was observed. From the 17 nights of observation during the campaign period, there was a good correlation between the OI 6300 depletion distances and the gravity wave horizontal wavelengths in the mesosphere with a statistically significant level, suggesting a direct contribution of the mesospheric gravity wave to plasma bubble seeding in the equatorial ionosphere.

PreviousNext No Access10th International Congress of the Brazilian Geophysical Society & EXPOGEF 2007, Rio de Janeiro, Brazil, 19-23 November 2007Simultaneous observation of ionospheric plasma bubble and mesospheric gravity wave activities during CAWSES 2005 SpreadFEx CampaignAuthors: H. Takahashi*P.-D. PautetJ. FechineM. A. AbduI. S. BatistaE. PaulaJ.H.A. SobralD. GobbiD. ArrudaP. P. BatistaF. S. SabbaM. J. TaylorA. F. MedeirosR. BuritiC. M. WrasseD. FrittsH. Takahashi*INPE, BrazilSearch for more papers by this author, P.-D. PautetINPE, BrazilSearch for more papers by this author, J. FechineINPE, BrazilSearch for more papers by this author, M. A. AbduINPE, BrazilSearch for more papers by this author, I. S. BatistaINPE, BrazilSearch for more papers by this author, E. PaulaINPE, BrazilSearch for more papers by this author, J.H.A. SobralINPE, BrazilSearch for more papers by this author, D. GobbiINPE, BrazilSearch for more papers by this author, D. ArrudaINPE, BrazilSearch for more papers by this author, P. P. BatistaINPE, BrazilSearch for more papers by this author, F. S. SabbaINPE, BrazilSearch for more papers by this author, M. J. TaylorUtah State University, USASearch for more papers by this author, A. F. MedeirosUFCG, BrazilSearch for more papers by this author, R. BuritiUFCG, BrazilSearch for more papers by this author, C. M. WrasseUNIVAP, BrazilSearch for more papers by this author, and D. FrittsCoRA, USASearch for more papers by this authorhttps://doi.org/10.1190/sbgf2007-404 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract During the SpreadFEx campaign from September 22 to November 8, 2005, two airglow CCD imagers, located at near Brasilia (14.8S, 47.6W, Mag. 10S) and at Cariri (7.4S, 36.5W, Mag. 9S) were operated simultaneously and measured the equatorial ionospheric bubble structures and their time evolution by monitoring the OI 6300 emission. From the 10 nights of coincident data, we observed that on some nights the bubbles was formed at the west of Cariri, but not seen from the Brasilia site. This suggests that the bubble formation and development started near the Cariri observation site. Identification of a longitudinal zone where the SpF is seeding is very important in order to find the mechanism of formation. The present paper will discuss SpF seeding mechanisms and possible contribution of the mesospheric gravity wave activity. Keywords: ionospheric, plasma, bubble, gravity wavePermalink: https://doi.org/10.1190/sbgf2007-404FiguresReferencesRelatedDetails 10th International Congress of the Brazilian Geophysical Society & EXPOGEF 2007, Rio de Janeiro, Brazil, 19-23 November 2007ISSN (online):2159-6832Copyright: 2007 Pages: 2431 publication data© 2007 Published in electronic format with permission by the Brazilian Geophysical SocietyPublisher:Society of Exploration Geophysicists HistoryPublished: 23 Nov 2007 CITATION INFORMATION H. Takahashi*, P.-D. Pautet, J. Fechine, M. A. Abdu, I. S. Batista, E. Paula, J.H.A. Sobral, D. Gobbi, D. Arruda, P. P. Batista, F. S. Sabba, M. J. Taylor, A. F. Medeiros, R. Buriti, C. M. Wrasse, and D. Fritts, (2007), "Simultaneous observation of ionospheric plasma bubble and mesospheric gravity wave activities during CAWSES 2005 SpreadFEx Campaign," SEG Global Meeting Abstracts : 2074-2076. https://doi.org/10.1190/sbgf2007-404 Plain-Language Summary Keywordsionosphericplasmabubblegravity wavePDF DownloadLoading ...