Pressure corrected daily mean SYO_MD_V count rate shown by red solid circles and the left vertical axis. ΔT_MSS (calculated with Eq. (3)) is shown by blue solid circles on the right vertical axis using an inverted scale. The left panel is calculated from the temperature below the 200 hPa altitude and the right panel from the temperature above the 200 hPa altitude. The SSW event is indicated by a red rectangle in both panels. Minor tick marks on the horizontal axis are indicated every 27 days.