Ring current decay during storm recover phase: RBSP Observation

Ring curent is an important current system in the Earth's magnetosphere. Many charged particles, especially protons and oxygen ions, move around the Earth due to due to electromagnetic drifts, which forms the ring current. During the main phase of a magnetic storm, ring current will grow stronger while it will decay slowly during recover phase. It is thought that charge exchange is the main mechanism of ring current decay [Daglis et al., 1999]. Hereby we use charge exchange theories to calculate charge exchange lifetimes of protons and oxygen ions during recover phase of many storms. Meanwhile, data of RBSP has been used for fitting in order to get real lifetimes of  protons and oxygen ions. We compared the observed lifetimes with the theory prediction and find that  a. the two are close at high L(>4) values and low energy(<55keV) for protons, b. the two are similar in a wide energy(1~600keV) range but a relatively narrow L(different at different energies) range, c. day or night make little difference on the comparison results.