Rocktsonde observations of the middle atmosphere dynamics at uchinoura(31°N,131°E) during the DYANA campaign. Part I: Outline of experiments and background conditions

We describe in this paper preliminary results on the characteristics of the wind velocity and temperature profiles obtained through rocketsonde measurements during the DYANA campaign. The wind velocity profiles in the height region of 20-90km, obtained with the rocketsondes, were compared with the results simultaneously observed with the MU (middle and upper atmosphere) radar at 60-100km. The profiles were consistent with each other up to 80km, when they were smoothed out for a height range of 8km. While for wind velocity fluctuations with vertical scales of a few km, the rocketsonde results showed significantly larger amplitudes than those obtained with the MU radar above 60km. Consideration of the vertical wavenumber spectra of the wind velocity fluctuations suggested that the maximum height range of the rocketsonde profile, by which the gravity wave characteristics can be delineated, seemed to be limited only up to about 60km. The background zonal winds were westward in the stratosphere, but they exhibited large time variations, coinciding with a minor stratospheric sudden warming. The temperature profiles also indicated great variability near the stratopause and in the mesosphere, probably due to the effect of the enhanced activity of planetary waves.