Fig. 9From: Penetration electric fields observed at middle and low latitudes during the 22 June 2015 geomagnetic stormZoomed in plots of Hp and He (Earthward) at around the tail magnetic dipolarization. The rapid decrease in He (dotted line) occurs concurrently with the rapid increase in Hp, which signifies a reconfiguration of the tail magnetic field at the onset of substormBack to article page