Ionospheric radio occultation inversion with the help of data assimillation

The traditional ionospheric radio occultation (IRO) inversion uses the assumption that electron density distribution is spherically symmetric, which is the main error source of IRO inversion. This article provides a new method without the assumption of spherical symmetry. We assimilate the GPS radio occultation and ground GPS observations into the ionosphere model, and get more accurate ionosphere information. Then the ionosphere assimilation result is used to constrain the IRO inversion. The inversion result is greatly improved, better than both the traditional method and the assimilation result.