Ionosphere occultation inversion method and anti-disturbance performance analysis

Ionosphere occultation inversion technique is an important means of the ionosphere exploration. Researches on its accuracy and anti-disturbance performance contribute to improve the retrieval results, which is also useful to assess the applied conditions of different methods. In this paper, we firstly analyses three kinds of inversion methods for the electron density in detail, including the Abel integral method, the 'Onion-layered' method and the least squares method. Then, we put forward a smoothing way by averaging three fitting functions with weights for the upper ionosphere. Eventually we discuss the retrieved accuracy and anti-disturbance performance of the inversion methods. And numerical simulations based on the calibrated TEC data of COSMIC are carried out. In conclusion, the retrieved accuracy of upper electron density significantly improves after the smooth, which verifies its effectiveness. In addition, the retrieved accuracy by 'Onion-layered' method is better than by the least squares method. But when the input disturbances present, the latter behaves better.