Fig. 12

Comparisons between predicted foEs and observed foEs. a Schematic figure showing the prediction time and the predicted period. Prediction for the 24–48 h later is made at 0 JST. The predicted foEs and the observed foEs for three different periods at Okinawa in late 2019 are compared: b DOY 184–200, c DOY 221–236, and d DOY 260–276. The red line indicates a series of predicted foEs of 24–48 h after the start of “free run” (without JRA-55 data). The black line indicates the observed foEs obtained by the ionosonde at Okinawa