How magnetic reconnection at dayside magnetopause effects on oxygen ions in the cusp

Abstract:

Conjunction observations of the electromagnetic field and plasma by Cluster and TC-1 at the dayside magnetosphere are presented to investigate the variations of oxygen ions characteristics in the cusp region during dayside magnetic reconnection period. The number density and energy flux of O⁺ ions from CIS/CODF instrument on Cluster spacecraft both increase significantly in the cusp after dayside magnetic reconnection. The oxygen ions with energy lager than 10 keV partially distributed in the anti-parallel direction along the background magnetic field. This result suggests that the dayside MR not only play a key role in the upward flowing of O+ ions from the ionosphere but also is an important source region of the energetic oxygen ions in the high altitude cusp . Our investigations provide confident evidence that the magnetic reconnection at dayside low latitude magnetopause can accelerate oxygen ions with energy of tens keV into the cusp region.