The global significance of cep events

Abstract

ABSTRACT Recently, a new magnetospheric phenomenon, CEPevent has been discovered. This discovery has created a great avenue for the Sun-Earth connection investigations. CEP events were detected in the high-altitude cusp for hours at a time, and each of the events is associated with a dramatic decrease and large fluctuations in the local magnetic field strength. Associated with these cavities are ions with energies from 40 keV up to 8 MeV that are more typical of the trapped ring current and radiation belt populations than the solar wind. By their geometry cusp magnetic field lines are connected to all of the magnetopause boundary layers and these cusp particles will form an energetic particle layer on the magnetopause. The intensities of the energetic ions were observed to increase by as large as four orders of the magnitudes during the cusp crossings, indicating the dayside high-altitude cusp is a key region for transferring the solar wind energy, mass, and momentum into the Earth’s magnetosphere. The charge state distribution of these cusp ions is indicative of their seed populations being a mixture of the ionospheric and the solar wind particles. These CEP events together with the cusp’s connectivity have significant global impacts on the geospace environment research and have been shedding light on the long-standing unsolved fundamental issue about the origins of the energetic particles in the ring current and in the upstream ion events. New observational facts demonstrate that these cusp energetic ions drift into the nightside plasma sheet along closed field lines, populate the dayside magnetopause boundary layer along closed/open field lines, and escape into the upstream and downstream regions along open field lines.