Study of ionospheric models for satellite orbit determination

Abstract

A study of empirical ionospheric models was undertaken to improve the accuracy of the ionospheric correction that is needed in satellite orbit determination. Our evaluation concerns the two most widely used empirical ionospheric models (Bent and international reference ionosphere (IRI)) and suggests improvements based on comparisons with satellite and ground‐based data. In both models, the topside electron density profiles decrease too sharply with increasing altitude. Our improved IRI topside formula compares well with AEROS satellite data and incoherent scatter measurements of the Jicamarca, Peru, radar facility. For the bottomside, a model for the effective parabolic thickness is introduced, based on the detailed IRI predictions. Recent progress in modeling the F2 peak altitude and electron density is reviewed. The increase in prediction accuracy compared to older F2 models is evaluated with Ionosphere Sounding Satellite b results (for density) and incoherent scatter measurements from Millstone Hill, Massachusetts (for altitude). The plasmaspheric electron content is also taken into account. Finally, results of a METEOSAT tracking exercise are used to check the ionospheric delays calculated with the different models. The changes indicated above were found to be helpful and resulted in an overall improvement.