Fig. 3
From: Electrodynamics of ionospheric weather over low latitudes
a All-sky images of OI 630-nm airglow emission taken at magnetic conjugate points, Boa Vista (BV), and Campo Grande (CG) in Brazil. The images show magnetic North–South aligned airglow depletion patches, symmetric in conjugate images, that are the footprint (in the airglow emission layer) of the flux tube aligned plasma depletions (Abdu et al. 2012); b The corresponding Digisonde ionograms; c TIMED/GUVI 135.6 nm images extending in the entire longitude span showing the global distribution of the EIA brightness and the patches of brightness depletions indicating plasma bubbles symmetric on either side of the dip equator (Kil et al. 2006)