PLANETARY WAVE ACTIVITY IN THE LOWER IONOSPHERE DURING CRISTA-I CAMPAIGN IN AUTUMN 1994 (OCTOBER-NOVEMBER)

On the basis of MEM spectrum analysis, the main planetary scale fluctu ations formed in the lower ionosphere are studied over a period of 3-2 5 days during the CRISTA campaign (October-November 1994). Three domin ant period bands are found: 3-5, 6-8 and 15-23 (mainly 16-18) days. Fo r 7-8 and 16-18 day fluctuations, propagation was eastward with wave n umbers K = 3 and K = 1, respectively. The magnitude of planetary wave activity in the mid-latitudes of the Northern Hemisphere during the CR ISTA campaign seems to be fairly consistent with the expected undistur bed normal/climatological state of the atmosphere at altitudes of 80-1 00 km.