Wave motions in the lower thermosphere during the Energy Budget Campaign 1980 from three locations in the Northern Hemisphere

Simultaneous meteor-radar wind observations were performed at Budrio, Italy (45 deg N), Sheffield, UK (53 deg N), and Stornoway, UK (58 deg N) during the Energy Budget Campaign, November-December 1980, in the height region between 75 and 115 km. Wind results are given in terms of prevailing components and oscillations of different time scales: tidal (8, 12, and 24 h), gravity (3-6 h), and planetary (2-10 day) waves. The variability of the winds in the upper mesosphere and lower thermosphere as observed in late autumn at the three stations is confirmed. It is shown that tidal wind components observed at Budrio exhibit amplitudes generally lower than those measured at the other two stations. The daily variations in the amplitudes of the semidiurnal wave at Budrio and Sheffield over time scales larger than 5-6 days suggest changes in the source, while the daily drift in the phase of this tide could mean that its vertical structure is consistent with short vertical wavelength propagating modes. The Budrio observations indicate the possible importance of gravity waves in the energy budget of the regions investigated.