Simultaneous storm time equatorward and poleward large‐scale TIDs on a global scale

Abstract

We report on the first simultaneous observations of poleward and equatorward traveling ionospheric disturbances (TIDs) during the same geomagnetic storm period on a global scale. While poleward propagating TIDs originate from the geomagnetic equator region, equatorward propagating TIDs are launched from the auroral regions. On a global scale, we use total electron content observations from the Global Navigation Satellite Systems to show that these TIDs existed over South American, African, and Asian sectors. The American and African sectors exhibited predominantly strong poleward TIDs, while the Asian sector recorded mostly equatorward TIDs which crossed the geomagnetic equator to either hemisphere on 9 March 2012. However, both poleward and equatorward TIDs are simultaneously present in all three sectors. Using a combination of ground‐based magnetometer observations and available low‐latitude radar (JULIA) data, we have established and confirmed that poleward TIDs of geomagnetic equator origin are due to ionospheric electrodynamics, specifically changes in E × B vertical drift after the storm onset.

Dynamic Response of Ionospheric Plasma Density to the Geomagnetic Storm of 22‐23 June 2015

“…They are induced by low-frequency fast moving traveling atmospheric disturbances with wavelengths of several thousand kilometers that can propagate over large distances. Such high velocities are typical of LSTIDs (Dashora et al, 2009;Habarulema et al, 2016;Ngwira, McKinnell, Cilliers, & Coster, 2012). Our claim on the excitation of these LSTIDs is supported by observations and derived quantities in Figure 1.…”

“…For instance, Habarulema et al (2016) suggest that changes in E×B vertical drift after the storm onset could be the source of poleward propagating TIDs, but on the other hand, the poleaward TIDs in the American sectors don't show any correlation with changes in E × B drift. However, the initiation process of poleward propagating TIDs originating at the dip equator is not quite clear.…”

“…These disturbances appear as increase or decrease of the plasma density distributions in the ionosphere (see, e.g., Buonsanto, 1999;Crowley, Emery, Roble, Carlson, & Knipp, 1989;Habarulema et al, 2016;Kuai et al, 2015;Mendillo, 2006;Ngwira, McKinnell, Cilliers, & Yizengaw, 2012). Storm-generated disturbances in electric fields, neutral winds, or composition changes can lead to profound modification of our planet's upper atmosphere through solar wind-magnetosphere-ionosphere interaction.…”

Assessing ionospheric response during some strong storms in solar cycle 24 using various data sources

“…This storm period has been previously studied and different ionospheric aspects reported on both regional and global scales [ Habarulema et al , , ]. Although the aim of considering 5 days (2 days before and after the storm) was to obtain quiet time reference, most of 7–11 March was disturbed and had storm‐related sources with causes elaborated by Tsurutani et al [].…”

“…These TIDs contribute to positive storm effects by moving the F region plasma up to altitudes of low loss rate, thus increasing ionospheric electron density. Recent results showed that TIDs of equator origin can also reach some parts of midlatitudes and contribute to positive storm effects [ Habarulema et al , , ]. Ionospheric response can vary significantly on storm to storm basis [e.g., Field and Rishbeth , ], and excellent reviews about ionospheric storms can be found in Buonsanto [] and Danilov [].…”