Are the Signals in the Sun's Mean Magnetic Field Associated With Coronal Mass Ejections?
Abstract
A study on time-frequency variability of the solar mean magnetic field (SMMF) using wavelet analysis is presented. The SMMF data of Michelson Doppler Imager (MDI) contain an offset most likely introduced by the random error of the exposure time of MDI. Without the offset correction, the peaks of wavelet power spectra for the full-disk SMMF time series coincide with the onset of coronal mass ejections. It has thus been suggested that the peak of wavelet power spectra is associated with coronal mass ejections [Boberg and Lundstedt 2000]. To localize the source of the peak, the full solar disk has been divided into four quadrants. It turns out unexpectedly that the time series for each quadrant closely resembles that of the full-disk series. In addition, all the five series are nearly in phase. On the other hand, the peaks of wavelet power spectra that coincide with coronal mass ejections disappear for the full-disk SMMF series obtained after the offset correction, suggesting that the signal actually occurs in the offset series. These results give rise to the question -- what is the cause of the signals detected in the offset series by the wavelet technique?
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2001
- Bibcode:
- 2001AGUSM..SH41A06L
- Keywords:
-
- 7500 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7513 Coronal mass ejections;
- 7524 Magnetic fields