Analysis of the 1.3–1.7 yr Oscillation Relationship between Solar and Geomagnetic Activities

• Published in: Chinese astronomy and astrophysics Vol. 43; no. 3; pp. 365 - 374
• Main Authors: Ya-wen, QIAN, Song, FENG, Lin-hua, DENG, Wei-hang, LIU
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2019
• Subjects: methods: data analysis; Sun: activity; Sunspots; Sun: activity; Sunspots; methods: data analysis
• ISSN: 0275-1062; 1879-128X
• DOI: 10.1016/j.chinastron.2018.09.012

The study on the 1.3–1.7 yr period of the solar and geomagnetic activities is very important for understanding the possible physical processes in the solar-terrestrial coupling system. The sunspot is the most prominent magnetic field structure in the solar photosphere, and the Ap index is an important indicator for the global geomagnetic activity level. The 1.3–1.7 yr period for the sunspot number and the geomagnetic Ap index is obtained by the synchro-squeezing wavelet transform, and the phase relationship between them is studied by the cross-correlation analysis. The main results are as follows: (1) The 1.3–1.7 yr period of the geomagnetic Ap index and sunspot number exhibits an intermittent evolutionary characteristics, and changes continuously with the time; (2) the geomagnetic Ap index has a higher periodic component in the odd solar cycles than the neighboring even solar cycles, which is characterized by fluctuations; (3) the phase relationship between the geomagnetic Ap index and the sunspot number is not always invariant, in most cases the geomagnetic Ap index lags behind the sunspot number, except in the 18th and 22th solar cycles.