Investigation of tidal wave activities over Wuhan by daytime sodium lidar

The first daytime sodium lidar observations in China were made in Wuhan(30°30'N,114°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.