HR: 0800h
AN: SA41A-1049 [Abstracts]
TI: Investigation of observed day-to-day variability in September mesopause region tidal-period
perturbations
AU: * Li, T
EM: taoli@lamar.colostate.edu
AF: Colorado State University, 200 West Lake St., Fort Collins, CO 80523-1875
AU: Williams, B P
EM: biffw@lamar.colostate.edu
AF: Colorado State University, 200 West Lake St., Fort Collins, CO 80523-1875
AU: She, C
EM: joeshe@lamar.colostate.edu
AF: Colorado State University, 200 West Lake St., Fort Collins, CO 80523-1875
AU: Liu, H
EM: liuh@ucar.edu
AF: High Altitude Observatory, National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO
80301
AB:
Simultaneous observations of the tidal-period perturbations (diurnal, semidiurnal, .etc) of temperature, zonal wind, and
meridional wind in the mesopause region (80km-105km) by the CSU two-beam Na lidar system in Fort Collins, Colorado between UT
day 264 and 272, September 2003 (a 9-day continuous campaign) indicate a dramatic day-to-day variability on tidal
amplitudes. Further analysis on the dataset with best fit to tidal perturbations within a running 24hr window reveals that in
addition to diurnal and semidiurnal tides, there exist 3-day and 5-day waves. We also observed a 2-fold increase in
amplitudes of temperature, zonal and meridional wind tides on the day 267-268. Whether this is the result of tidal-gravity
wave nonlinear interaction, or of planetary wave modulation is the main objective of this paper. Time series of the
temperature vertical profiles for day 267 shows a strong temperature inversion with a near adiabatic lapse rate above. We
find that at the altitude near adiabatic lapse rate, the semidiurnal and diurnal tides are in-phase so that the total
negative temperature gradient due to tidal contribution was increased to near adiabatic lapse rate. The observed temperature
inversion and accompanying change in zonal wind are consistent with wave breaking. Analysis in this direction invoking both
TIME-GCM simulation and TIMED/SABER observed temperatures providing a global perspective will be made.
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3360 Remote sensing
DE: 3384 Waves and tides
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting