A Statistical Model of Inner Magnetospheric Electron Density: Van Allen Probes Observations

Based on electron density observations between September 2012 and July 2019 from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on board the Van Allen Probes (VAPs) spacecraft, this paper makes a statistical investigation on the distribution of inner magnetospheric electron density in the magnetic equatorial plane (MEP) under different Kp levels, and further develops a new model of inner magnetospheric electron density in the MEP with multi‐parameters (Kp, SYM‐H, Pdyn, F10.7). The statistical results show that the plasmaspheric electron density in the inner magnetosphere in the MEP has an obvious Magnetic Local Time (MLT) distribution characteristic. With the increase of Kp index, the asymmetrical distribution of plasmaspheric electron density in the MEP increases, reaching the maximum value of erosion at MLT = 02:00, and the erosion at MLT = 14:00 is much less than that at MLT = 02:00. The distribution of plasmaspheric electron density in the low L‐value (L is shell parameter) region (L ≤ 2.8) is less affected by the geomagnetic activity than that in the high L‐value region (L ≥ 3.6). Comparison between the model outputs and the VAP's observations indicates that this statistical model could accurately describe the dynamic distribution characteristics of plasmaspheric electron density in the MEP during geomagnetic storms, such as erosion and refilling, and can be applied to space weather forecast. Plain Language Summary The Van Allen Probes Mission (hereinafter referred to as the VAPs) is committed to study the extreme and dynamic regions of space known as the Van Allen Radiation Belts that surround the Earth. Based on the VAP observations, this paper makes a statistical analysis of the electron density distribution of inner magnetosphere in the Magnetic Equatorial Plane (MEP), and constructs a new model that can reflect the electron density distribution of plasmasphere in the inner magnetosphere in the MEP under different geomagnetic conditions. The model outputs are in good consistency with the observed data for different geomagnetic activity conditions. It is shown that this model could accurately describe the dynamic distribution characteristics of inner magnetospheric electron density in the MEP during geomagnetic storms, such as plasmaspheric erosion and refilling. This model can be used to establish three‐dimensional plasmaspheric electron density model. This investigation is helpful to eliminate the positioning de