Dynamics of the Earth's ionosphere in spherical functions

This paper examines the time series of spherical decomposition coefficients of global maps of the total electron content of the Earth's ionosphere. It has been demonstrated that zonal harmonics correlate well with the 11-year cycle of solar activity; tesseral harmonics of the 1st order have a pronounced daily periodicity. The resulting series of spherical expansion coefficients will be used to construct a model of the ionosphere.