抚仙湖太阳观测和研究基地知识库

Coronal mass ejections (CMEs) are energetic expulsions of organized magnetic features from the Sun. The study of CME quasiperiodicity helps establish a possible relationship between CMEs, solar flares, and geomagnetic disturbances. We used the angular width of CMEs as a criterion for classifying the CMEs in the study. Based on 25 yr of observational data, we systematically analyzed the quasiperiodic variations corresponding to the CME occurrence rate of different angular widths in the northern and southern hemispheres, using frequency and time-frequency analysis methods. There are various periods for CMEs of different angular widths: 9 months, 1.7 yr, and 3.3-4.3 yr. Compared with previous studies based on the occurrence rate of CMEs, we obtained the same periods of 1.2 (+/- 0.01), 3.1 (+/- 0.04), and approximate to 6.1 (+/- 0.4) months, and 1.2 (+/- 0.1) and 2.4 (+/- 0.4) yr. We also found additional periods of all CMEs that appear only in one hemisphere or during a specific solar cycle. For example, 7.1 (+/- 0.2) months and 4.1 (+/- 0.2) yr in the northern hemisphere, 1 (+/- 0.004) and 5.9 (+/- 0.2) months and 1 (+/- 0.1), 1.4 (+/- 0.1), and 2.4 (+/- 0.4) yr in the southern hemisphere, 6.1 (+/- 0.4) months in solar cycle 23, and 6.1 (+/- 0.4) months and 1.2 (+/- 0.1) and 3.7 (+/- 0.2) yr in solar cycle 24. The analysis shows that quasiperiodic variations of the CMEs are a link among oscillations in coronal magnetic activity, solar flare eruptions, and interplanetary space.