Fig. 2From: Physical mechanism for the temporary intensification of wintertime sporadic E layers in 2009Daily average foEs as observed by the ionosonde at Kokubunji in 2009 (upper panel) and 2011 (lower panel). The ranges in yellow indicate the periods from 24 DOY (January 24) to 54 DOY (February 23) when the temporary WiEsL intensification was observed in 2009Back to article page