Abstract
Abstract. The first-ever high resolution 2-D maps of OI 630.0 nm dayglow obtained from equatorial latitudes clearly reveal the movement as a large-scale feature of the equatorial ionization anomaly (EIA). These also show the presence of wave-like features classified as gravity waves presumably originating at the crest of the EIA, similar to the equatorial electrojet acting as a source of these waves. These results are presented and discussed.Key words. Atmospheric composition and structure (Airglow and aurora) · Ionosphere (Equatorial ionosphere; Instruments and techniques).
Highlights
Both large- and small-scale processes extended in space and time continue to occur in the Earth's upper atmosphere as an outcome of the dynamical behaviour of the dierent regions responding to external energy inputs
The equatorial ionization anomaly (EIA) is generated by the E B drift [Vd (E B)/ B 2] experienced by the plasma over the dip equator
The OI 630.0 nm dayglow emission serves as a good indicator for investigating the processes of the ionosphere owing to the thermosphere-ionosphere coupling. Measurement of these emissions by the unique dayglow photometer resulted in obtaining the ®rst twodimensional maps with a temporal resolution of $12 min and these maps revealed the evolution of the EIA, including the movement of its crests and its spatial extent
Summary
Both large- and small-scale processes extended in space and time continue to occur in the Earth's upper atmosphere as an outcome of the dynamical behaviour of the dierent regions responding to external energy inputs. As the eastward electric ®eld strength increases during the course of a day due to the intensi®cation of global scale dynamo action, the drift, Vd, too, increases in consonance and the plasma which is lifted to higher heights is (eventually) transported poleward due to ®eld aligned diusion. This would appear as the movement of the excess density in ionization (i.e. thecrest'), in latitude with time and is generally referred to as themovement of the crest of the ionization anomaly'. The development of the anomaly shows day-to-day as well as long period (such as season, solar cycle, etc.) variabilities
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
