Improving the NeQuick Model in the Plasmasphere Through Radio Occultation and POD TEC Observations

The NeQuick model utilizes three empirical parameters (H 0 , g, and r) to define the effective scale height in the topside ionosphere and plasmasphere, which drives vertical electron density variations. However, previous studies have identified weaknesses in the NeQuick topside model, particularly the underestimation of the plasmaspheric contribution to the total electron content (TEC). To address these shortcomings, the study aims to improve the NeQuick model's empirical representation of electron density distribution in the topside ionosphere and plasmasphere. Radio occultation (RO) electron density profiles from COSMIC/FORMOSAT-3 satellites are integrated with TEC measurements from the same mission derived from precise orbit determination (POD) antennas. A novel two-step optimization procedure is developed for the r parameter, which is critical for describing the plasmaspheric electron density. This process initially derives H 0 , g, and r from RO observations and subsequently refines the r parameter by incorporating PODderived TEC data, yielding a more robust representation of the plasmasphere. The optimized r parameter, derived from a dataset spanning from 2006 to 2018, demonstrates improved consistency with effective scale height observations from the Van Allen Probes (VAP). The results reveal that the improved parameterization of r better captures the spatial, temporal, and solar activity-dependent variations in the topside ionosphere and plasmasphere compared to the fixed value traditionally used