Investigation of the variation of the neutral density wave pattern on the basis of San Marco V data

Neutral density measurements by the Drag Balance Instrument (DBI) on board the Italian San Marco V satellite are made with high time resolution. These measurements permit the direct investigation of the thermospheric wave pattern variation in the equatorial zone. The investigation has been carried out not only statistically, but also through case studies. One of the interesting results is that, although the wave amplitude generally increases continuously with altitude, there are some cases when it changes abruptly. These abrupt changes can occur at different altitudes. The coupling processes such as ion drag and spatial resonance have also been studied as a function of altitude (h), local solar time (LST) and other parameters.