Fig. 11

Altitudes of the CHAMP (red) and the Swarm Bravo (orange), Alpha, and Charlie (blue) satellites, as indicated by the left scale, and the \(F_{10.7}\) solar radiation index (green), as indicated by the right scale, from 2000 to the end of the CIY4 data envelope. The solid dark lines show the daily mean altitude, while the shaded areas indicate the range (difference between daily max and daily min)