NEW RESULTS BY SZ-4 ATMOSPHERIC COMPOSITION MEASUREMENT

An atmospheric composition detector with a quadruple mass spectrometer on board spacecraft SZ-4 was launched on 30 December 2002. Based on the analysis of the three month’s （2003-01-2003-03） data, during these months the summer just located at the southern hemisphere of the earth, and occurred some geomagnetic disturbances, the new results of the abnormal change of the thermospheric composition （near 330-362 km） are measured first. The results show that the density of N₂ clearly increased, in contrast, the density of O showed a decrease, and occurred only at the higher latitudes of the southern hemisphere, during the peak of geomagnetic disturbances. It was quite different in comparison with the results of SZ-2 and SZ-3, where these abnormal change occurred at higher latitude of the northern hemisphere. The reason causing above mentioned phenomena might be related to the en ergetic particle input into the pole and high latitude region which heats the upper atmosphere in a large scale and produce a large scale air upstream which brings the air from lower altitude up to higher altitude and results in the above mentioned abnormal change. These abnormal change occurred at the different hemisphere, it seems that the abnormal change may occur only at hemisphere of Summer season.