高层大气原子氧的半年周变

地球高层大气成分的长期变化受太阳黑子周、太阳活动程度和地磁活动程度等诸多因子所控制．本文利用国外有关高层大气成分的数据，分别讨论受上述控制因子影响的高层大气成分长期变化，讨论范围仅限原子氧半年周期变化．选用LDEF在轨飞行器1984年4月—1990年1月高度470km附近的长期资料进行统计分析，结果表明，高度470km附近原子氧在年平均太阳黑子数＜20、太阳活动程度相对低而平稳期间，半年周期的变化尤为明显，相对变幅约为40％—60％、井随平均太阳黑子数增加而增大．而年平均太阳黑子数峰值的1989年期间（＞120），半年变化的相对变幅可达87％左右．

A SEMI-ANNUAL VARIATION OF THE ATOMIC OXYGEN IN THE UPPER ATMOSPHERE

The long-term variation of the atmospheric composition in the Earth's upper atmosphere are controlled by 11-year cycle of the number of sunspots, varied solar and geomagnetic activity and so on. Satellite composition measurements showed that composition variations occurred. In this paper, the discussions are based on data from Satellite LDEF, and only represented in send-annual variation of the atomic oxygen (LDEF, spent 5 years and 10 months in LEO, from 1984 to 1990). The results show that a send-annual variation of the atomic oxygen is very clear, especially during the solar minimum (the mean annual sunspot number< 20). The density of the atomic oxygen changes 40%-60%, and the total amount of variations is further enhanced by the increasing of the sunspots number, while the change is up to 87% during the solar maximum (in 1989, the mean annual sunspots number > 120).