Ionospheric electron density profiling and modeling of COSMIC follow-on simulations

The formosat-3/ constellation observing system for meteorology, ionosphere and climate (fs3/cosmic) has been proven a successful mission on profiling ionospheric electron density $$( {n_e })$$ using the radio occultation (ro) technique. a follow-on program (called fs7/cosmic2) is now in progress. the fs3/cosmic follow-on mission will have six 24 $$^{circ }$$ -inclination and 550-km low earth orbiting (leo) satellites and six 72 $$^{circ }$$ -inclination and 750-km leo satellites to receive tri-g (gps, glonass, and galileo) satellite signals. fs7/cosmic2 ro observations were simulated in this study by calculating limb-viewing gnss-to-leo tec values separately through two independent ionospheric models (the twim and nequick models). we propose a compensatory abel-inversion scheme to improve vertical $$n_e $$ profiling and three-dimensional (3d) $$n_e $$ modeling in this fs7/cosmic2 simulation study with future real observations. in this fs7/cosmic2 feasibility study the number of ro observations will increase of around 10 times compared with fs3/cosmic, and the windowing day number to collect $$n_e $$ profiles and to derive every half-hour 3d $$n_e $$ model could be decreased from 30 to 3 days. the results show that the root-mean-square (rms) fof2 and hmf2 difference improvements are 46 % (32 %) and 21 % (4.6 %), respectively, in relative percentage over the standard abel inversion at the twim-background (nequick-background) simulation experiment. the rms modeling errors are about one order less than those from fs3/cosmic simulations.