广州地磁Z分量日变幅的谱特征

利用1972—1993年广州地磁资料,分析了Z分量日变幅的年平均、年变化和半年变化等低频成分的逐年变化,以及小于60天的短周期变化特征．同时对1972—1993年的F10.7日均值进行了谱分析．结果指出,广州地磁Z分量日变幅的年平均与太阳活动指数F10．7的年平均存在良好的线性相关;具有幅度大约5nT夏季极大的年变化,与太阳活动没有明显相关,是一种季节效应;存在春秋分极大的半年变化,幅度与太阳活动有关,高年的幅度明显大于低年;具有明显的与太阳自转相关的27天左右的变化和明显的与行星波有关的接近16日、10日、5日、2日等短周期变化．广州地磁Z分量日变幅的这些谱特征,有助于更深入地了解中低层大气对电离层影响的物理机制．

SPECTRAL CHARACTERISTICS OF DAILY RANGES OF Z COMPONENT AT GUANGZHOU GEOMAGNETIC STATION

Using the geomagnetic data of daily variation of Z component observed from 1972 to 1993 at Guangzhou station, the low frequency components that include the annual average, the annual variation and the semiannual variation, and the short period component with periods less than 60-day are analyzed year after year. The daily averages of the F_(10.7) also are analyzed. The daily variations of Z at Guangzhou station can approximately reflect the magnitude of the equatorial electro jet. The results show that, the annual averages of daily variations of Z are favorably linearly correlative with the annual averages of the F_(10.7); the annual variation with the amplitude of about 5 nT and summer maxima is existent in every year, it is not virsually correlative with the solar activity and it is a seasonal effect; the semiannual variation with equinoctial maxima is existent, the amplitude of the semiannual variation is obviously greater at solar maximum than at solar minimum, for example, the amplitude of the semiannual variation is about 10 nT at 1981 that is the year of solar activity maximum, but the amplitude is about 2 nT at 1976 that is the year of solar activity minimum; the oscillation with period about 27 day which relate to solar rotation and the oscillations with periods close to 16, 10, 5, 2 d which relate to the planetary wave are obviously existent. The spectral characteristics of the geomagnetic daily ranges of Z at Guangzhou station prompts further investigation into the physical mechanism of that the ionosphere is affected by the middle and lower atmosphere.