Equatorial depletions in the 630.0 nm airglow at Vanimo

Using ground based airglow photometry, depletions in the 630.0 nm airglow were observed at Vanimo near the southern limb of the intertropical airglow arc. The results were compared with the more common properties of equatorial plasma bubbles such as depletion magnitude, cross-sectional size and East-West drift, with good agreement. In particular, airglow depletion depths ranged from 18 to 64% with a maximum loss in emission rate of 700 R (55%) on a night when the maximum recorded airglow was almost 1700 R. This corresponds to an electron density depletion of about 1.5 × 10¹² el m ^?3 observed near solar maximum. It is somewhat higher than values reported near solar minimum. The airglow depletions move eastward with velocities ranging from 90 to 140 ms ^?1. There is qualitative evidence of vertical motion and strong correlation with range type spread F.