HR: 1340h
AN: SA43A-1089    [Abstracts]
TI: Observations of sub-planetary scale diurnal waves in the equatorial mesosphere and lower thermosphere
AU: * Lieberman, R S
EM: ruth@co-ra.com
AF: Northwest Research Associates, Colorado Research Associates Division, 3380 Mitchell Lane, Boulder, CO 80301 United States
AU: Riggin, D M
EM: riggin@co-ra.com
AF: Northwest Research Associates, Colorado Research Associates Division, 3380 Mitchell Lane, Boulder, CO 80301 United States
AU: Garcia, R R
EM: rgarcia@ucar.edu
AF: NCAR, P O Box 3000, Boulder, CO 80307 United States
AU: Wu, Q
EM: qwu@ucar.edu
AF: NCAR, P O Box 3000, Boulder, CO 80307 United States
AB: The power spectrum of vertically propagating waves excited by tropical heating has a strong diurnal component at planetary and inertia-gravity wave (IGW) horizontal scales. Observation-driven numerical modeling studies indicate that IGW's provide a significant source of momentum for the semiannual oscillation (SAO) in the equatorial zonal mean winds. We seek observatinal confirmation of the importance of diurnal IGW's for the SAO. We have analyzed global patterns of ascending and descending node differences in MLT tropical winds and temperatures. The difference fields are separated by 8-12 hours (depending upon the dataset), and are therefore considered diurnal proxies. Juxtaposed upon the planetary-scale features are localized longitudinal variations with zonal wavenumbers larger than 5. These "intermediate-scale" variations are vertically coherent, and can persist for several weeks. The total temperature variance of wavenumbers 9-16 is examined in relation to the underlying stratospheric mean winds. Stronger variances generally coincide with periods where the underlying zonal mean winds are either relatively weak, or unidirectional. The inverse association between variance and zoal mean wind magnitude is suggestive of a wave filtering mechanism.
DE: 3334 Middle atmosphere dynamics (0341, 0342)
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005