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​Ionospheric tomography

By observing the ionospheric delay of the two-frequency radio waves (1575.42 MHz, 1227.60 MHz) transmitted from the GPS satellite with a ground receiver, it is possible to determine the Slant TEC between the satellite and the receiver.*1. This method is widely used as an extremely effective method in upper-level physics.

It is possible to reconstruct the electron density distribution by solving the inverse problem using Slant TEC over many raypaths, but it is difficult to solve this accurately due to the limited number of data and the lack of horizontal raypaths. Not. In many cases, reconstruction is achieved using some kind of initial distribution or a priori information, but such methods are not suitable for reconstructing disturbance structures.*twenty three.

Therefore, in order to solve the problems caused by the limited number of data and the lack of horizontal ray paths, we developed a method using neural networks and GPS data (RMTNN method:*Four), it is possible to reconstruct from a small amount of data without relying on a specific ionospheric model.*5, 6.

*1 Mannucci et al., 1998

*2 Austen et al., 1988

*3 Seemala et al., 2014

*4 Ma et al., 2005

*5 Hirooka et al., 2011

*6 Hirooka et al., 2014

Radio waves being transmitted from a GPS satellite to the earth

Fig.1 GPS appearance

GPS tomography

Fig.2 Ionospheric tomography results over North America

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