Size of the radiation pressure acceleration relative to the aerodynamic acceleration, where the size is measured by the RMS of the acceleration within a sliding one-month window. The curves show the ratio of the RMS of the radiation pressure acceleration over that of the aerodynamic acceleration in the along-track (top) and cross-track direction (center). The bottom panel shows the altitude evolution of the satellites and the solar activity as indicated by the F_10.7 solar radio flux index.