New insight on the internal waves in the equatorial thermosphere by the S-Marco 5 spacecraft data

Waves with both acoustic and internal gravity characteristics have been recorded by the S. Marco 5 spacecraft during its operation in 1988. The data set evidenced the dependence of the number of wave events upon the local time (with maxima during nighttime) and a correlation with simultaneously measured ionospheric irregularities: Although an accurate analysis of the possible influence of the experimental environment has been already made during the first analysis which indicated the physical nature and the reliability of these data, a supplementary investigation has been added by way of demonstration and is discussed in this paper. Since the gravity waves are recognized as a possible mechanism for the insemination of the the ionospheric bubbles phenomena. the correlation between waves and bubbles events detected on the ion density (IVI) and in the zonal electric field component (EFI) is not surprising. The previously presented analysis proved the correlation on the basis of the occurrence frequency of the bubbles and wave events. In this paper an attempt will be made to analyse the contemporary behaviour of ionospheric, electric and neutral density data searching for point by point possible correspondence and related interaction mechanisms. (C) 1999 COSPAR. Published by Elsevier Science Ltd.