Overview and summary of the Spread F Experiment (SpreadFEx)
David C. Fritts,M. A. Abdu,B. R. Batista,Inez S. Batista,Paulo Batista,Ricardo Buriti,Barclay Clemesha,Thomas Dautermann,E. R. de Paula,B. J. Fechine,Bela G. Fejer,Delano Gobbi,Jennifer S. Haase,Farzad Kamalabadi,E. A. Kherani,Brian Laughman,P. P. Lima,Hanli Liu,Amauri Fragoso de Medeiros,Pierre-Dominique Pautet,Dennis M. Riggin,Fabiano S. Rodrigues,F. T. São Sabbas,J. H. A. Sobral,P. Stamus,H. Takahashi,Michael J. Taylor,Sharon L. Vadas,Fabio Vargas,Cristiano Max Wrasse +29 more
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TLDR
The Spread F Experiment (or SpreadFEx) as mentioned in this paper performed from September to November 2005, with primary measurements in Brazil, was used to define the potential role of neutral atmosphere dynamics, specifically gravity wave motions propagating upward from the lower atmosphere, in seeding Rayleigh-Taylor instability and plasma bubbles extending to higher altitudes.Abstract:
. We provide here an overview of, and a summary of results arising from, an extensive experimental campaign (the Spread F Experiment, or SpreadFEx) performed from September to November 2005, with primary measurements in Brazil. The motivation was to define the potential role of neutral atmosphere dynamics, specifically gravity wave motions propagating upward from the lower atmosphere, in seeding Rayleigh-Taylor instability (RTI) and plasma bubbles extending to higher altitudes. Campaign measurements focused on the Brazilian sector and included ground-based optical, radar, digisonde, and GPS measurements at a number of fixed and temporary sites. Related data on convection and plasma bubble structures were also collected by GOES 12, and the GUVI instrument aboard the TIMED satellite. Initial results of our SpreadFEx analyses are described separately by Fritts et al. (2009). Further analyses of these data provide additional evidence of 1) gravity wave (GW) activity near the mesopause apparently linked to deep convection predominantly to the west of our measurement sites, 2) small-scale GWs largely confined to lower altitudes, 3) larger-scale GWs apparently penetrating to much higher altitudes, 4) substantial GW amplitudes implied by digisonde electron densities, and 5) apparent influences of these perturbations in the lower F-region on the formation of equatorial spread F, RTI, and plasma bubbles extending to much higher altitudes. Other efforts with SpreadFEx data have also yielded 6) the occurrence, locations, and scales of deep convection, 7) the spatial and temporal evolutions of plasma bubbles, 8) 2-D (height-resolved) structures in electron density fluctuations and equatorial spread F at lower altitudes and plasma bubbles above, and 9) the occurrence of substantial tidal perturbations to the large-scale wind and temperature fields extending to bottomside F-layer and higher altitudes. Collectively, our various SpreadFEx analyses suggest direct links between deep tropical convection and large GW perturbations at large spatial scales at the bottomside F-layer and their likely contributions to the excitation of RTI and plasma bubbles extending to much higher altitudes.read more
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Simulation of the seeding of equatorial spread F by circular gravity waves
TL;DR: In this article, the authors model the coupling of both circular (local) and plane wave (nonlocal) gravity waves to the bottomside F layer as a mechanism for triggering equatorial plasma bubbles, and support the hypothesis that nonplane gravity waves can more strongly couple to the F layer than plane gravity waves.
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Gravity wave initiation of equatorial spread F/plasma bubble irregularities based on observational data from the SpreadFEx campaign
TL;DR: In this paper, the role of gravity waves in the instability initiation leading to equatorial spread F development was investigated using ground-based experiments conducted during the 2005 SpreadFEx campaign in Brazil.
Journal ArticleDOI
Gravity wave penetration into the thermosphere: sensitivity to solar cycle variations and mean winds
David C. Fritts,Sharon L. Vadas +1 more
TL;DR: In this paper, a broad range of gravity wave phase speeds, spatial scales, and intrinsic frequencies were considered to address all of the major gravity wave sources in the lower atmosphere potentially impacting the thermosphere.
Journal ArticleDOI
Simultaneous observation of ionospheric plasma bubbles and mesospheric gravity waves during the SpreadFEx Campaign
H. Takahashi,Michael J. Taylor,Pierre-Dominique Pautet,Amauri Fragoso de Medeiros,Delano Gobbi,Cristiano Max Wrasse,Joaquim Fechine,M. A. Abdu,Inez S. Batista,Eurico R. de Paula,J. H. A. Sobral,Daniela C. S. Arruda,Sharon L. Vadas,F. S. Sabbas,David C. Fritts +14 more
TL;DR: In this article, 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 airglove OI 6300 intensity depletions.
Journal ArticleDOI
Gravity wave and tidal influences on equatorial spread F based on observations during the Spread F Experiment (SpreadFEx)
David C. Fritts,Sharon L. Vadas,Dennis M. Riggin,M. A. Abdu,Inez S. Batista,H. Takahashi,Amauri Fragoso de Medeiros,Farzad Kamalabadi,Hanli Liu,Bela G. Fejer,Michael J. Taylor +10 more
TL;DR: In this paper, the authors used the results of the SpreadFEx campaign to estimate gravity wave characteristics at the bottomside F layer, and to assess their possible con- tributions to optimal seeding conditions for equatorial spread F and plasma instability growth rates.
References
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