Abstract

Coronal Mass Ejections (CMEs) are the major factor that affects the interplanetary medium and space weather. We perform a statistical analysis of the coronal mass ejections from solar minimum to post solar maximum of solar cycle 23 (1996-2003). We study velocities, accelerations, widths and heliocentric latitude of emergence (position angle), their variation with time, as well as possible interdependences among them. The data set come from the observations of CMEs by the SOHO LASCO C2 or C3 coronographs. An increase of the average CME velocity is found from solar minimum to solar maximum. The average acceleration however remains close to zero through the observation period, yet the standard deviation of the distribution of CME accelerations increases as the CME "ejection rate" increases with increasing solar activity. The average width is almost constant, while its standard deviation increases drastically. The latitude of appearance of CMEs changed drastically with the phase of the solar cycle, following the inclination of the heliospheric current sheet and the appearance of filaments on the solar disc. As expected the flare appearance on the disc during the solar cycle follows the sunspot appearance and it is not related with the pattern of appearances of CMEs at the same phase of the solar cycle. The relation of the CME average velocity with the average solar wind velocity is also discussed.

X. Moussas, A. Hillaris, P. Preka-Papadema
Section of Astrophysics, Astronomy and Mechanics
Department of Physics
University of Athens
Panepistimiopolis, GR-15784 Zographos, Athens, Greece
E-mail: xmoussas@cc.uoa.g,r ahilaris@cc.uoa.gr, ppreka@cc.uoa.gr

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