HR: 09:21h
AN: AE51A-07 INVITED     [Abstracts]
TI: Detection of Acoustic Emission From Sprites
AU: * Farges, T
EM: thomas.farges@cea.fr
AF: CEA, DASE/LDG, BP 12, Bruyeres le Chatel, 91680 France
AU: Blanc, E
EM: elisabeth.blanc@cea.fr
AF: CEA, DASE/LDG, BP 12, Bruyeres le Chatel, 91680 France
AU: Le Pichon, A
EM: alexis.lepichon@cea.fr
AF: CEA, DASE/LDG, BP 12, Bruyeres le Chatel, 91680 France
AU: Neubert, T
EM: neubert@dsri.dk
AF: DSRI, Juliane Maries Vej 30, Copenhagen O, 2100 Denmark
AU: Allin, T
EM: tha@oersted.dtu.dk
AF: DTU, Bldg. 327, Lyngby, 2800 Denmark
AB: During the summer of 2003, complementary measurements were taken in Europe during the Sprite2003 campaign to study sprites and associated processes. More than 70 sprites observed by light-sensitive optical cameras located at the Observatoire du Pic du Midi in the Pyrenees mountains were found to correlate with chirp-like signals of several tens seconds to one minute duration measured by an infrasound station at Flers (France) which was distant from the thunderstorms of 300-1200 km. Using an acoustic wave propagation model, the observed propagation delays, frequency dispersion, and duration of the infrasound bursts are found to be consistent with source altitudes at 60-80 km with horizontal dimensions equal to the optical width of the sprites. The chirp-like dispersion is a result of the propagation properties in the earth-thermosphere waveguide. The sprite activity identified by the infrasound signature continued past sunrise into the daytime where optical systems cannot be used, documenting the occurrence of daytime sprites.
DE: 3324 Lightning
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3384 Waves and tides
SC: Atmospheric and Space Electricity [AE]
MN: 2004 AGU Fall Meeting