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- Title
Dynamics of the Tongue of Ionizations During the Geomagnetic Storm on 7 September 2015: The Altitudinal Dependences.
- Authors
Zhang, Kedeng; Song, Huimin; Wang, Hui; Liu, Jing; Wang, Wenbin; Wan, Xin; Wang, Dedong; Jin, Yaqi
- Abstract
Using the electron density (Ne) observations from the Defense Meteorological Satellite Program, and Constellation Observing Systems for Meteorology, Ionosphere, and Climate mission and simulations from the Thermosphere Ionosphere Electrodynamic General Circulation Model. we investigate the dynamic evolution of the polar tongue of ionization (TOI) from double to single structures at different altitudes during a geomagnetic storm. The modeled Ne depicted that double and single TOIs occurred at altitudes above 300 km, respectively. During the northward turning of interplanetary magnetic field (IMF) Bz, the afternoon TOI disappeared and the morning TOI was reduced. The plasma transport due to neutral winds and ambipolar diffusion facilitated (prevented) the depletion of plasma density of the morning TOI at 300 (500) km, with a relative contribution of 42.8% and 28.6% (−15.4% and −76.9%), respectively. Downward E × B drifts led to an enhancement/reduction of plasma density in the storm enhanced density region in the lower/upper ionosphere. During the duskward turning of IMF By, the morning TOI could be mostly attributed to the anti‐sunward plasma drifts (75.8% at 300 km, 100% at 500 km), with a relatively stronger role of the zonal component than that of meridional E × B drifts. The upward E × B drifts were important/ignorable in the upper/lower ionosphere. Both the neutral winds and ambipolar diffusion resulted in an accumulation of plasma density of the morning TOI at 300 km indirectly (24.2%), however, their roles were minor at 500 km. Plain Language Summary: The ionosphere is part of Earth's upper atmosphere, ranging from 80 to about 1,000 km. The tongue‐like structures occurring in ionospheric electron density in the polar region are an interesting and important phenomenon at high latitudes. During storm (a major disturbance of Earth's ionosphere due to the Sun) time, the electron density is accumulated in the storm enhanced density (SED) region, and enters into the polar region, forming the tongue of ionizations (TOIs). Note that SED occurs at afternoon midlatitudes. The temporal behavior of TOIs at different altitudes is interesting and deserves further exploration. The potential drivers for this behavior can depend greatly on altitudes. This is key to the understanding of dynamic and electrodynamic processes in the coupled ionosphere‐thermosphere system at different altitudes. Key Points: The double (single) tongue of ionization (TOI) occurs at altitudes above 300 kmThe neutral winds, and ambipolar diffusion facilitated (prevented) the depletion of plasma at morning TOI at 300 (500) kmThe anti‐sunward plasma drifts account for 75.8% and 100% of morning TOI at 300 and 500 km during the duskward turning of interplanetary magnetic field By
- Subjects
MAGNETIC storms; THERMOSPHERE; IONOSPHERIC electron density; INTERPLANETARY magnetic fields; GENERAL circulation model; UPPER atmosphere; LATITUDE
- Publication
Journal of Geophysical Research. Space Physics, 2023, Vol 128, Issue 11, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2023JA031735