Fig. 1From: Penetration electric fields observed at middle and low latitudes during the 22 June 2015 geomagnetic stormMaps of the HF Doppler sounders in Japan, Czech Republic and Republic of China (red) and of magnetometers at high-equatorial latitudes (blue). The dip-equator is shown with the red curve. Details of the stations are listed in Table 1Back to article page