Periodogram Analysis on Solar Activities Based on El Campo Solar Radar Observation Data

Solar radar can transmit radar waves toward the Sun actively at a specific waveband and receive the reflected waves. By analyzing the echoes, we can obtain the information of motion, magnetic field, and other properties of the solar atmosphere. The El Campo solar radar has done regular observations on the solar corona for 8 years from 1961 to 1969, to trace the variation of solar activities. We have made a periodicity analysis on the obtained data with the Lomb-Scargle periodogram algorithm, and found that there are the 200 day and 540 day periods existed in the variation of the measured solar radar cross section. In addition, we have selected the larger radar cross sections (≥ 20σ⊙) to compare with the Dst indexes. Finally, we have summarized the El Campo solar radar experiment and give a prospect for the future development of the solar radar observation.