With the appearance of such satellite systems as GPS, GLONASS, Galileo, and others, the total electron content TEC measured by means of navigational satellites became a key parameter characterizing a state of the ionized space. In turn, functioning of navigational and telecommunication systems needs models of TEC for an estimation of accuracy of positioning, for the short-term and long-term prediction of this parameter. In this Chapter, empirical models of the total electron content are presented. The new result is their comparison. It is shown that the majority of them provide an adequate accuracy and reliability. As the basic application of TEC measurements, the problem of determination of maximum concentration NmF2 of the ionosphere with use of its equivalent slab thickness τ is considered. It is shown that existing models of τ are not global and do not provide sufficient accuracy in determining NmF2. An approach for new global model is offered.
Part of the book: Empirical Modeling and Its Applications
This chapter includes four sections. The first introduction section provides a brief review of the existing methods of transionospheric sounding and the results obtained, and the shortcomings of each are noted. The second section describes the proposed principle based on the installation of a receiver on the GLONASS platform. The advantages and technical characteristics of the proposed system are justified. The main area of use is the polar region. The third section presents the most modern modeling methods and models used. To calculate the propagation of radio waves, this is a method of ray tracing taking into account the large- and small-scale inhomogeneities of the ionosphere. To describe the state of the ionosphere, it is proposed to use the IRI2016 model, which includes adaptation to the current diagnostic data provided by ground ionosondes, and the IRI-Plas model, which not only can be adapted to ground ionosonde data, but also to values of the total electronic content, the measurement of which is an additional advantage of the proposed system. The fourth sectionincludes areas of application, the main of which is the monitoring of the polar region, and the least provided with ionospheric information.
Part of the book: Satellite Information Classification and Interpretation