Earth Planets Space, Vol. 58 (No. 9), pp. 1131-1137, 2006
B. P. Williams1, D. C. Fritts1, J. D. Vance2, C.-Y. She2, T. Abe3, and E. Thrane4
1NorthWest Research Associates, Colorado Research Associates division, Boulder, Colorado, USA
2Department of Physics, Colorado State University, Fort Collins, Colorado, USA
3ISAS/JAXA, Kanagawa, Japan
4University of Oslo, Oslo, Norway
(Received October 2, 2005; Revised July 24, 2006; Accepted July 31, 2006; Online published September 29, 2006)
The sounding rocket for the DELTA (Dynamics and Energetics of the Lower Thermosphere in Aurora) campaign was successfully launched from Andoya at 00:33 UT on Dec 13, 2004. Though it was cloudy at the time of launch, the Weber Na lidar was operating intermittently between 20:00 UT and 23:30 UT on Dec 12, observing Na density, temperature and meridional wind between 80 and 100 km. Throughout the lidar observations, we observed significant small (λz<5 km) and medium-scale (λz≈8-15 km) wave activity producing significant wind and temperature shears. There were unusually large (up to 10 m/s and 10 K amplitudes) perturbations of the vertical wind and temperature profiles at 21 UT with a 3 km vertical wavelength that was much stronger in the vertical beam than in the north beam. The atmosphere appeared to become more active as the launch time approached. During the last interval with data, at ~23:20 UT, Dec. 12th, the lidar profiles revealed a gravity wave in both beams with a magnitude of 5-10 K in temperature and approximately 5 km vertical wavelength. The large background shear plus the wave perturbation produced regions with potential convective instability at multiple altitudes.
Key words: Mesopause dynamics, temperature structure, instabilities, gravity waves.