Fig. 7From: Periodic oscillations of Doppler frequency excited by the traveling ionospheric disturbances associated with the Tonga eruption in 2022A map showing the geometry of GNSS TEC measurements for GPS PRN8, PRN16, and PRN27. The red circle shows the position of GNSS receiver (0161). The black circles show the reflection points of the mid points between the transmitters and receiversBack to article page