Investigation of tidal wave activities over Wuhan by daytime sodium lidar

The first daytime sodium lidar observations in China were made in Wuhan (30 degree 30'N, 114 degree E). In a long observation cycle lasting more than two days, the sodium layer presented strong diurnal variations. The sodium column density, layer width and centroid height, all presented 24 h periodic variations. The density variation at each height also presents a clear 24 h downward wave phase propagation. All these can be attributed to a prominent diurnal tidal wave perturbation, and the derived phase agrees very well with that obtained from the GSWM00 model. A large sodium diurnal variation was also presented in three other shorter daytime observations, while the mean diurnal variations of the sodium layer present a prominent structure of diurnal tidal wave propagation. These results agree with early reports, namely, that the diurnal tide component is the dominant tide wave over Wuhan.