HR: 16:15h
AN: SA34A-02    [Abstracts]
TI: The 2-day wave in the mesosphere observed by SABER
AU: * Garcia, R R
EM: rgarcia@ucar.edu
AF: NCAR, 1850 Table Mesa Drive, Boulder, CO 80305
AU: Lieberman, R
EM: ruth@colorado-research.com
AF: Colorado Research Associates, 3380 Mitchell Lane, Boulder, CO 80301
AB: A large-scale oscillation with period near 2 days is a ubiquitous feature of the summer mesosphere; it has been detected in ground-based and satellite observations, and reproduced with a variety of numerical models. The current consensus is that the 2-day oscillation is forced through baroclinic instability of the summertime stratospheric jet and takes the form of the gravest Rossby-gravity normal mode of zonal wavenumber k=3. We present SABER observations for 2002-2004 that strongly support this view, and show further that the 2-day wave is part of a set of normal modes excited in the vicinity of the region of strong curvature of the summer jet. Besides the k=3, RG mode, these include the k=4 RG mode (~1.8 days), and Rossby modes at k=2 (2.5-3 days) and k=1 (~5 days). SABER observations also reveal that the wavenumber composition of this 2-day ``complex" is different in southern and northern summer, at least in the data currently available from SABER.
DE: 3332 Mesospheric dynamics
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3384 Waves and tides
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting