The Response of Middle Thermosphere (∼160 km) Composition to the November 20 and 21, 2003 Superstorm

Abstract

The response of thermospheric composition to geomagnetic storms has been studied for several decades. The first such study was carried out by Seaton (1956), who proposed that an increase in molecular oxygen (O 2 ) number density might account for the decrease of electron density during a major storm that took place on January 25, 194925, . Jacchia (1959 first presented evidence of thermospheric density increases during storms using the measured changes in satellite orbital elements, which were explained in terms of atmospheric heating during geomagnetically disturbed conditions. Prölss and von Zahn (1974aZahn ( , 1974b and Prölss (1980Prölss ( , 1987Prölss ( , 2011 did further studies on the storm-time perturbations in composition, mainly by using the in situ multi-satellite observations near 300 km (e.g., Dynamics Explorer [DE]-2 and ESRO 4 satellites). Based on these studies, a picture of the main thermospheric compositional perturbations during geomagnetic storms was established: an increase of heavier constituents (molecular nitrogen [N 2 ] and oxygen [O 2 ]), and a height-dependent change of atomic oxygen (O) at high-latitudes and middle-latitudes (decreases at lower heights (<∼300 km) and increases higher up); an increase of all constituents at low latitudes over all heights in the thermosphere. In addition, the basic evolution of these perturbations can be described as follows. When a storm begins, strong temperature enhancements occur at high latitudes due to Joule heating, which lead to upward winds (Burns et al., 1995). The nitrogen-rich air is brought up from lower altitudes into the upper thermosphere. The horizontal pressure gradient from temperature differences, in conjunction with ion drag, drives strong horizontal wind changes within a few hours (Ponthieu et al., 1988;Prölss, 2011). Horizontal winds transport the nitrogen-rich air toward the middle-low latitudes at night (

The Height‐Dependent Delayed Ionospheric Response to Solar EUV

“…TIE‐GCM calculates the major species (O, O 2 , and N 2 ) using vertical molecular diffusion, vertical eddy diffusion, horizontal and vertical advection as well as production and loss due to chemical reactions (Cai et al., 2021; Qian et al., 2014; Sutton et al., 2015; Yu et al., 2021). The O + density is calculated according to the continuity equation considering transport due to neutral winds, transport due to ambipolar diffusion, E × B transport as well as production Q and loss L due to chemical reactions (Liu et al., 2016) $$$\frac{\partial n}{\partial t}-Q+L\cdot n=-\nabla \left(n\cdot {\mathbf{v}}_{i}\right).$$$ The ion velocity v i combines the different transport processes in Equation .…”

“…The strong shift of the 27-day signature for O and O 2 at low heights, which is also observed in Figure 7, reflects the role of ionization and recombination on the delayed ionospheric response (Ren et al, 2018) and reveals to which extent the photodissociation has to be considered. The 𝐴𝐴 Ψ𝑁𝑁 2 profiles are estimated according to the implementation (Yu et al, 2021) as…”

“…The strong shift of the 27‐day signature for O and O 2 at low heights, which is also observed in Figure 7, reflects the role of ionization and recombination on the delayed ionospheric response (Ren et al., 2018) and reveals to which extent the photodissociation has to be considered. The $${{\Psi}}_{{N}_{2}}$$ profiles are estimated according to the implementation (Yu et al., 2021) as $$${{\Psi}}_{{N}_{2}}=1-{{\Psi}}_{{O}_{2}}-{{\Psi}}_{O},$$$ and present the interaction of O and O 2 . For that reason, the results are shown in Figures 7 and 10 to provide a complete overview of the major species.…”

Relation of Extreme Ionospheric Events with Geomagnetic and Meteorological Activity

“…The electric field is not the only source of extreme increase in the electron density. The important role of thermospheric composition changes was demonstrated by Yu et al [5]. Their study showed that the increase in the oxygen mass density reached up to ~90% during the 20-21 November 2003 superstorm.…”

“…In this paper, we take an unconventional approach to the study of extreme ionospheric events. Instead of investigating ionospheric responses to extreme space weather events (as is usual for case studies [1][2][3][5][6][7][8][9][10][11][12] or statistical investigations [15][16][17]), we collect statistics of extreme ionospheric disturbances from datasets of two ionosondes. Similar to our study, the extreme values of TEC over Japan with frequencies of once per year, 10 years, and 100 years were investigated using 22-year GPS TEC measurements and 62-year ionosonde slab thickness observations [18].…”