Abstract

Based on nearly 4.6 million radio occultation ionospheric profile data from COSMIC satellites in 2006-2020, a global three-dimensional ionospheric electron density model was constructed by a new concept. The global 3D ionosphere structure was divided into total 338,661 grids with longitude intervals of 10 degrees, latitude intervals of 2 degrees, and height intervals of 5 km. Each individual grid model is first constructed, and then all grid models are combined to form a global ionospheric model. Each grid model has 21 coefficient for modeling solar activity, geomagnetic activity, local time, and season variation.This method makes full use of all ionospheric electron density data without any spatial smoothing, and can effectively model the fine ionospheric spatial structure like longitudinal wavenumber-4 structure in low latitudes. The model also takes into account the influence of both solar and geomagnetic activities on the ionosphere. It can give the climatological variation of ionospheric electron density with geomagnetic activity. In addition, by combined with the International Reference Ionospheric electron density results of E layer below 140km, the problem of three-peak error of occultation data below peak height of F2 layer in middle and low latitude region is effectively solved, and accurate low-altitude profile data can be obtained. Compared with other data sources such as ZH01 and ROCSAT-1, the simulation ability of the model in fine spatial structure is verified.