Mesosphere–Ionosphere Coupling Processes Observed in the F Layer Bottom-Side Oscillation
During the Spread FEx campaign, under the NASA Living with a star (ILWS) program which was carried out in the South American Magnetic Equatorial region from September to November 2005, we observed formation of the bottom-type spread F and simultaneous occurrence of mesospheric gravity wave events. The events were monitored by the ionosonde, coherent radar and airglow OI 630.0 nm and OH imager. It is found that the bottom-type scattering layer has a wave form generated most probably by local gravity waves. Reverse ray-tracing of the observed gravity waves indicate their possible sources in the troposphere or thermosphere. Forward ray-tracing indicates their penetration into the ionosphere. The present work summarizes the observational evidence and results of the data analysis and discusses the mesosphere–ionosphere coupling processes.
KeywordsGravity Wave Lower Thermosphere Plasma Bubble Meteor Radar Rayleigh Taylor
The authors thank for several institutions and observatory staffs by whom the ground based observations were carried out. Thanks are also due to Maria Goreti S. Aquino who reduced the ionogram data. São Luis VHF radar was developed and installed by the support of FAPECP under the process 2004/01065-0. The RTI images were prepared by Eng. Lazaro A. P. Camargo. We thank for him. The SpreadFEx field program and data analysis were supported by NASA under contracts NNH04CC67C and NAS5-02036. The present project was also partially supported by CNPq (Conselho Nacional de Desenvolvimento Cietífico e Tecnológico) under contract 301876/2007-0.
- Fritts DC, Vadas SL, Yamada Y (2002) An estimate of strong local body forcing and gravity wave radiation based on OH airglow and meteor radar observations. Geophys Res Lett 29(10). doi:10.1029/2001GL013753Google Scholar
- Takahashi H, Abdu MA, Taylor MJ et al (2010) Equatorial ionosphere bottom-type spread F observed by OI 630.0 nm airglow imaging. Geophys Res Lett 37. doi:10.1029/2009GL041802Google Scholar
- Tsunoda RT (2008) Satellite traces: an ionogram signature for large-scale wave structure and a precursor for equatorial spread F. Geophys Res Lett 35. doi:101029/2008GL035706Google Scholar
- Vadas SL (2007) Horizontal and vertical propagation and dissipation of gravity waves in the thermosphere from lower atmospheric and thermospheric sources. J Geophys Res 112. doi:10.1029/2006JA011845Google Scholar
- Vadas SL (2010) Downward-propagating secondary gravity waves in the OH airglow layer from thermospheric body forces resulting from deep convection. J Geophys Res. submittedGoogle Scholar
- Vadas SL, Crowley G (2010) Sources of the traveling ionospheric disturbances observed by the ionospheric TIDDBIT sounder near Wallops Island on October 30, 2007. J Geophys Res 115. doi:10.1029/2009JA015053Google Scholar
- Vadas SL, Fritts DC (2006) Influence of solar variability on gravity wave structure and dissipation in the thermosphere from tropospheric convection. J Geophys Res 111. doi:10.1029/2005JA011510Google Scholar