【摘要】 本文通过对中纬地区地磁 Z 分量五次谐波的分析,得到振幅及位相随纬度分布变化及各次谐波变化规律:夏季衰减最大;随纬度的增加 m=1,2,3次谐波冬季比夏季和春季下降快;冬季的位相变化较快。焦点纬度（?）f（Z）和（?）f（H）符合较好。1980年 A₁、A₂、A₃较59年大,但衰减较快。更多还原

【Abstract】 Through the analysis of the 5th harmonic waves of the geomagnetic Z component in the middle latitude areas, this paper shows the distribution of amplitude and phase of such waves varies with latitude, and the regularities in. the variation of each harmonic wave is also discussed. The attenuation reaches its maximum in summers. With the latitude increases (m = 1 , 2, 3), the harmonic wave quickly falls in winters as compared with in summers and springs and the phase changes very fast in winters. The focus latitude φf(Z) agrees quite well with φf(H) . A1, A2 and A3 took greater values in 1980 as compared with in 1959 except that they attenuated much quickly.更多还原