HR: 14:50h
AN: A53E-08    [Abstracts]
TI: Four years of gravity waves monitoring in Antarctica : Impact for global atmospheric studies
AU: * Blanc, E
EM: elisabeth.blanc@cea.fr
AF: Commissariat Energie Atomique Laboratoire de Detection et de Geophysique, BP12, Bruyeres le Chatel, 91680, France
AU: Le Pichon, A
EM: lepichon@dase.bruyeres.cea.fr
AF: Commissariat Energie Atomique Laboratoire de Detection et de Geophysique, BP12, Bruyeres le Chatel, 91680, France
AU: Ceranna, L
EM: ceranna@sdac.hannover.bgr.de
AF: Federal Institute of Geosciences and Natural Ressources, Stilleweg 2, Hannover, 30655, Germany
AB: The development of the Infrasound International Monitoring System, used for the verification of the Comprehensive Test Ban Treaty, offers a powerful way to measure, permanently and at a global scale, the atmospheric waves at different latitudes. Infrasound stations using several microbarometers are very sensitive acoustic antennas, measuring the main characteristics of infrasound waves including velocity and direction of the wave front. Associated with new data processing methods, a global analysis of the atmospheric disturbances is now possible in a large frequency range. The networks if mostly sensitive to infrasound in the range 0.01 to 10 Hz, but most of gravity waves, which are characterized by very large amplitudes, are also detected by the network. The Antarctic stations are especially interesting for the study of gravity waves, because they are controlled by the polar vortex, and because they are rarely disturbed by the low latitude mountain gravity waves activity which is less important than in the Northern hemisphere. The monitoring of the gravity wave activity in the Antarctica station I27DE from 2003 up to 2007 reveals two active gravity wave systems. The first one, characterized by an azimuth from East, is produced in the troposphere by the wind blowing over mountains. The second system, characterized by an azimuth from West, is correlated with the wind and the temperature gradients in the lower stratosphere and is related with the polar stratospheric vortex. During magnetic storms infrasound waves are generally observed with a North azimuth at frequencies from 0.5 Hz to few Hz, however, gravity waves are generally not observed. A strong wave system has been observed coming from North only once in January 2005 several days after a major magnetic storm. The origin of this wave system in terms of magnetic storm or other processes related with the global dynamics of the stratosphere is discussed.
DE: 3319 General circulation (1223)
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3362 Stratosphere/troposphere interactions
DE: 3384 Acoustic-gravity waves
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting