Simultaneously-formed Wedge-like Structures of Different Ion Species Deep in the Inner Magnetosphere

Abstract:

Ion data from the HOPE spectrometers onboard Van Allen Probes reveal the existence of wedge-like structures of O⁺, He⁺ and H⁺ ions deep in the inner magnetosphere, which are found at the Mcllwain L shells of L=2-5 in this study. The behaviors of the wedge-like structures in terms of temporal evolution, spatial distribution, upper energy limit, as well as dependence on solar wind and different geomagnetic indices are investigated from both event studies of several consecutive orbits on 3 February 2013 and the subsequent statistical analyses using four years of data. Unlike the dominant distribution at L=4-8 in the dayside observed by the polar orbit satellites in previous studies, the wedge-like structures deep in the equatorial plane of the inner magnetosphere have a preferential location in the duskside and nightside. The O⁺ and He⁺ structures can extend to smaller L shells with higher upper energy limits than the H⁺ structures. Observations indicate that these wedge-like structures are probably attributed to fresh substorm injections from the outer region.