Ionospheric plasma bubble zonal drift: a methodology using OI 630 nm all-sky imaging systems

Abstract

With the recent advances in all-sky imaging technology for nightglow emission studies, the F-region OI 630 nm emission has become an important tool for ionospheric/thermospheric coupling studies. At equatorial and low latitude regions, the all-sky imaging observations of the OI 630 nm emission show quasi north-south aligned intensity depletion bands, which are the optical signatures of large scale F-region plasma irregularities. By observing the motion of the intensity depleted bands it is possible to infer the ionospheric plasma zonal velocity of the depletion. The north-south aligned structures seen in the field of view of the all-sky imaging system corotate with the ionospheric plasma, so that by calculating the spatial displacements occurring during successive OI 630 nm emission images we can infer the ionospheric plasma drift velocity. However, the plasma bubbles have their own internal space-time dynamics leading to changes in their shape and dimensions and this may induce some errors in the calculated drift velocities. In this paper we take into account the space-time changes in the plasma bubbles in order to calculate the ionospheric plasma zonal drift velocities using the OI 630 nm nightglow emission.