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A three-dimensional ionospheric electron density (Ne) model (L.-C.Tsai,C.H.Liu,T.Y.Hsiao,and J.Y.Huang,Radio Sci.,44,doi:10.1029/2009RS004154,2009) has been namedthe TaiWan Ionospheric Model (TWIM) and constructed from global distributed ionosonde foF2and foE data and vertical Ne profiles retrieved from FormoSat3/COSMIC GPS radio occultationmeasurements.The TWIM exhibits vertically-fitted α-Chapman-type layers,with distinct F2,F1,E,and D layers,and surface spherical harmonics approaches for the fitted layer parametersincluding peak density,peak density height,and scale height.These results are useful ininvestigation of near-Earth space and large-scale Ne distribution.This way the continuity of Neand its derivatives is also maintained for practical schemes for providing reliable radiopropagation predictions.We have presented a numerical and step by step ray-tracing method (L.-C.Tsai,C.H.Liu,and J.Y.Huang,Radio Sci.,45,doi:10.1029/2010RS004359,2010) on the TWIMand including an Earth-centered magnetic dipole and horizontal Ne gradient effects.