大气行星波对LF和VLF无线电波传播的影响

EFFECTS OF THE ATMOSPHERIC PLANETARY WAVES ON RADIO WAVE PROPAGATION AT LF AND VLF

本文采用最大熵谱估计方法,对1985-1987年三个冬天,在东半球(20°S—65°N、13°E—141°E)白天观测的LF和VLF电波相位、幅度、卫星观测的Ly-α射线通量及高纬上空的行星波活动等大量资料,进行了熵谱分析。观测及分析结果表明:(1)LF和VLF电波的相位具有2—2.2天、3—4天、6—12天、12—20天、20—32天周期范围的行星尺度扰动.Ly-α射线辐射通量主要具有20—32天周期范围内的波动.(2)发现在中纬地区冬天观测的LF电波幅度大的扰动与高纬60°N上空观测的行星波H_1的变化规律非常一致. 波形结构的主要峰和谷几乎完全对应,仅在时间上前者约滞后3—4天.计算给出两者的相关系数在0.65—0.85之间.根据观测事实和谱分析结果对比,作者认为LF和VLF电波相位、幅度周期在20天以上的扰动主要受太阳Ly-α辐射通量变化的控制.冬天其周期在2—20天范围内的扰动,主要受来自对流层和下平流层中激发的大气行星波的影响.

In this paper, using the method of the maximum entropy spectrum estimation, three kinds of data are analysed. They include phase and amplitude of LF and VLF observed in the Eastern hemisphere (20°S-65°N, 13°E-141°E), Ly-α radiation flux measured by satellite, and the planetary wave in the high latitude during three winters from 1985 to 1988. These results show that(1) The phase disturbances at LF and VLF have periods with 2-2.2, 3-4, 6-12, 12-20 and 20-32 days, while the solar I.y-α radiation flux presents 20-30 days fluctuation as well.(2) In the winter, larger amplitude distubmces at LF have fairly good correlation to the planetary wave H1 observed in the high latitude (60°N), valleys and peaks of their wave forms correspond each other except shifting about 3-4 days in the time axis. Cross correlation coefficients are between 0.65 and 0.85, We also notice that there are little differences between them.The observed results are compared with those of the spectral analyses, and considered that Ly-a radiation flux variation could be a reason which causes disturbances of LF and VLF with period more than 20 days, while those with periods ranging from 2 to 20 days seem to be controled by the planetary waves from the stratosphere and troposphere.