Solar cycle variation of real CME latitudes

Abstract

With the assumption of radial motion and uniform longitudinal distribution of coronal mass ejections (CMEs), we propose a method to eliminate projection effects from the apparent observed CME latitude distribution. This method has been applied to SOHO LASCO data from 1996 January to 2006 December. As a result, we find that the real CME latitude distribution had the following characteristics: (1) High-latitude CMEs ($\theta >60^{\circ }$ where $\theta$ is the latitude) constituted 3% of all CMEs and mainly occurred during the time when the polar magnetic fields reversed sign. The latitudinal drift of the high-latitude CMEs was correlated with that of the heliospheric current sheet. (2) 4% of all CMEs occurred in the range $45^{\circ }\le \theta \le 60^{\circ }$. These mid-latitude CMEs occurred primarily in 2000, near the middle of 2002 and in 2005, respectively, forming a prominent three-peak structure; (3) The highest occurrence probability of low-latitude ($\theta <45^{\circ }$) CMEs was at the minimum and during the declining phase of the solar cycle. However, the highest occurrence rate of low-latitude CMEs was at the maximum and during the declining phase of the solar cycle. The latitudinal evolution of low-latitude CMEs did not follow the Spörer sunspot law, which suggests that many CMEs originated outside of active regions.

4 pages, 4 figures, accepted by ApJ Letter

References in corpus (1)

• Source Regions of Coronal Mass Ejections

Cited by in corpus (2)

• Signature of Extended Solar Cycles as Detected from Ca II K Synoptic Maps of Kodaikanal and Mount Wilson Observatory
• The interplanetary mass ejections behaviour in the heliosphere