HR: 16:20h
AN: SA24A-01 INVITED     [Abstracts]
TI: Initial Results of the Spread F Experiment (SpreadFEx): Overview and Evidence of Possible Gravity Wave Excitation of Equatorial Plasma Bubbles
AU: * Fritts, D C
EM: dave@cora.nwra.com
AF: Colorado Research Associates Div. NorthWest Research Associates, 3380 Mitchell Lane, Boulder, CO 80301, United States
AB: The Spread F Experiment (SpreadFEx) was performed in Brazil by Brazilian and U.S. researchers during two ~20- day periods extending from September to November 2005. We employed extensive ground-based and space- based observations of gravity waves, plasma structures, electron densities, and mean atmospheric and ionospheric conditions using airglow, digisonde, VHF and meteor radar, balloon, GPS and satellite instrumentation at multiple sites in Brazil and with GUVI aboard the TIMED satellite. These measurements focused on deep convection, gravity waves, and plasma bubble structures. This comprehensive data set has provided the first promising indications of the specific roles of gravity waves arising from deep convection and other sources in contributing to the seeding of equatorial spread F and plasma bubbles extending to high altitudes. This talk will summarize the campaign results related to possible neutral atmosphere seeding of spread F and plasma bubbles during these observations. Specifically, our measurements have revealed significant neutral density (and related wind and temperature) perturbations extending from ~80 km well into the thermosphere and ionosphere. Many of these appear to arise from deep convection over the Amazon basin. Others occurring at larger scales under magnetically-disturbed conditions may have auroral or other higher-latitude sources. Both appear to lead, on occasion, to sufficiently large perturbations of the bottomside F layer to trigger plasma bubbles extending to much higher altitudes thereafter. Upon completion of our analyses, we believe that these observations will yield the first persuasive evidence of the role of neutral atmosphere gravity waves in the seeding of equatorial plasma bubbles.
DE: 2415 Equatorial ionosphere
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 3369 Thermospheric dynamics (0358)
DE: 3384 Acoustic-gravity waves
SC: SPA-Aeronomy [SA]
MN: 2007 Joint Assembly