Based on lidar measurements beteen March and September 2001, the charccteristics of sporadic Na layers (Na, layers) over wuhan (30.5

By amdyzing tile resutts of the numerical sinlulations ol nonlinear propagation of three Gaussian gravlly-wave packms in isothermal atmosphere individually, tile nonlinear effects on the characteristics of glavity waves are studied quantitatively. The analyses show that during the nonlinear propagation of gravity wave packets the mean fows are accelerated and the vertical wavelengths show clear reduction due to non-linearity 011 the other band, though nonlinear effects exist, the time variations of the fi'equencies of gravity wuve packets are close to those derived from the dispersion relation and the amplitude and phase relations of wave-associated disturbance components are consistent with the pledictions of the polarization rchttion of giavity waves. This indicates that the dispersion and polarization rehltions based on the linear grawty wave theory can be applied extensively in the nonlinear region

Here is die first report on the observation of meteor ablation trails with tidar in China. Four long-lived Na ablation trails were el)served during the 18/19 Nov, 2001 Leonid meteor shower with a sodium resunance lidar over Wuhan. The Mean altitude of the 4 trails is 97.95kin. coaststeal with Leonid high entry velocity (-72kn/s). The peak deusit) averages about 3380

Winds and waves measured by the Medium Frequency Radars (MFR) at Saskatoon (52N, 107W), Robsart (49N, lg9W), and Sylvan Lake (52N, 114w), and the Fabry-Perot Interferometer (FPI) at Saskatoon are compared. Particular care has been taken to exclude FPI airglow (558 nm, green line) contamination by aurora or scatter from clouds; radar data were setected from high slgnal-to-noise conditions. Comparisons between the MFR/FPI in seasonal wind climatologies (at a radar height of 98km) and wind speed ratios and direction-difference histograms for the Saskatoon systems show excellent agreement. Zonal and meridional wind comparisons (scatter plots) also show no significant differences in mean winds between the FPI and MFR. Differences between instantaneous measurements, as seen on 91 individual days, are categorized into four types of events, depending upon FPI/MFR similarities and differences and the dominance of the solar tide A gravity wave model is then used to demonstrate the effects of waves, with scales from hundreds to several thousand of kilometers, upon such optical and radar systems, each of which has a different inherent spatial averaging. The model is largely successful in explaining the differences between the instantaneous MFR and FPI measurements. The relevance of such comparisons to satellite/ground-based collaborations is briefly discussed.