Visualizing sporadic E using aeronautical navigation signals at VHF frequenciesKeisuke Hosokawa, Kotaku Kimura, Jun Sakai, Susumu Saito, Ichiro Tomizawa, Michi Nishioka, Takuya Tsugawa and Mamoru IshiiJ. Space Weather Space Clim., 11 (2021) 6DOI: https://doi.org/10.1051/swsc/2020075