Vol 12, No 1 (2012) / Li

Kinematics and amplitude evolution of global coronal extreme ultraviolet waves

Ting Li, Jun Zhang, Shu-Hong Yang, Wei Liu

Abstract

With the observations of the Solar-Terrestrial Relations Observatory (STEREO) and the Solar Dynamics Observatory (SDO), we analyze in detail the kinematics of global coronal waves together with their intensity amplitudes (so-called “perturbation profiles”). We use a semi-automatic method to investigate the perturbation profiles of coronal waves. The location and amplitude of the coronal waves are calculated over a 30˚ sector on the sphere, where the wave signal is strongest. The position with the strongest perturbation at each time is considered as the location of the wave front. In all four events, the wave velocities vary with time for most of their lifetime, up to 15 min, while in the event observed by the Atmospheric Imaging Assembly there is an additional early phase with a much higher velocity. The velocity varies greatly between different waves from 216 to 440 km s−1 . The velocity of the two waves initially increases, subsequently decreases, and then increases again. Two other waves show a deceleration followed by an acceleration. Three categories of amplitude evolution of global coronal waves are found for the four events. The first is that the amplitude only shows a decrease. The second is that the amplitude initially increases and then decreases, and the third is that the amplitude shows an orderly increase, a decrease, an increase again and then a decrease. All the extreme ultraviolet waves show a decrease in amplitude while propagating farther away, probably because the driver of the global coronal wave (coronal mass ejection) is moving farther away from the solar surface.

Keywords


Sun: corona — Sun: coronal mass ejections (CMEs) — Sun: flares

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