Deep-seated gravitational slope deformations (DSGSDs) with characteristic sackung landforms (e.g., double crests, trenches, uphill-facing scarps, and toe bulging) are considered by some researchers to be diagnostic features indicating past mountain glaciations.
This further supports the thought that the double-crest pattern measured by Swarm in Figs. 6 and 7 is due to a combined effect of IEFs and the ionospheric disturbance wind dynamo, with a contribution of the latter which is definitely smaller, thus causing an inversion of the usual dynamo zonal electric field from westward to eastward.
About periods M1/M2, for the morning sector (Figs. 6, 7), IRI still models an equatorial pattern characterized by a maximum centered on the magnetic equator, while Swarm measures a double-crest pattern in the west longitude sector of the globe, that is unusual for these local times.
It is interesting to note how the double-crest pattern in the M2 period is still recorded by Swarm A and not by Swarm B, suggesting that, in the 2 h of MLT difference characterizing the two satellites, the plasma fountain from direct became again reverse.
Concerning the period P1 (the same is for the period P2), for the evening sector (Fig. 9), the equatorial band shows for both IRI and Swarm the same usual electron density double-crest pattern around the magnetic equator (e.g., Balan and Bailey 1995).
With reference to periods M1/M2, for the evening sector (Figs. 10, 11), the usual electron density double-crest pattern around the magnetic equator is still shown by both IRI and Swarm, even though the crests measured by Swarm are noticeably narrower than those modelled by IRI.
In summary, Figs. 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 show that, from a morphological point of view, the electron density patterns measured by Swarm and those modelled by IRI are different, especially during the main phase of the storm, for the morning sector, when Swarm highlights an unusual double-crest pattern.
Other types of composite shapes have diverging and doubled crests, either resulting from the splitting of an initial DB or rather from the merging of two DBs with different orientation.
The basic one is a simple black, yellow and white tricolour and others are variations on this, including the imperial double headed eagle crest.
One is a plain tricolour and the other features a double-headed eagle crest.
