We delineated the climatological characteristics of the potential energy of gravity waves, Ep, using Rayleigh lidar observations made in 1990--1991 at Tsukuba, Japan (36 ¿N, 140 ¿E). Tendency of large and small values of Ep in winter and summer, respectively, was detected in the upper stratosphere (30--45 km), suggesting annual variation with a winter maximum. This annual cycle seemed to be consistent with lidar observations made in France and UK [Wilson et al., 1991; Mitchell et al., 1991>. The obtained Ep values in the upper stratosphere and lower mesosphere (45--60 km) were rather similar to the French data, despite the large scatter of the Tsukuba values. ¿ American Geophysical Union 1994