All‐Sky Imaging Observations of the Interaction Between the Brightness Wave and ESF Airglow Depletions

The midnight temperature maximum (MTM) and equatorial spread F (ESF) are common processes in the low‐latitude ionosphere and thermosphere. This work shows the first interaction between the brightness wave (BW), associated with the MTM, and plasma depletions, associated with ESF. Observations from the El Leoncito all‐sky imager (ASI) (31.8°S, 69.3°W, 19.7°S magnetic latitude) show concurrent observations of a plasma depletion and a BW. As the BW passes through the depletion, the depletion is modified and becomes an enhancement. Concurrent measurements at the conjugate location show an airglow depletion, indicating that the enhancement is an evolution of the depletion and not a separate feature and that it only occurs in one hemisphere. Previous model results were able to recreate the evolution of an airglow depletion into an enhancement when there is a poleward wind combined with converging zonal winds. We discuss how these wind conditions are often associated with the MTM/BW and can explain this observed enhancement. Key Points Presented here is the first observation of an interaction between a BW and an ESF depletion ESF depletion evolves into an enhancement in only one hemisphere as the BW passes by Evolution of the ESF structure is attributed to neutral winds associated with the MTM/BW