• Journal of Space Technology and Applications
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• v.3 no.3
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• pp.239-256
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• 2023

The Earth's ionosphere is an area where part of the upper atmosphere is ionized and exists in a plasma state that affects radio waves. It is a field that has been studied for a long time as it directly affects real life in relation to communications. Depending on the altitude, it is divided into D, E, and F layers depending on the main ions that make up the electron density. The density of the neutral atmosphere is very large compared to the electron density, so it should be described as plasma taking that effect into account. It is an area where influences from outside the ionosphere are directly reflected, starting from the sun and extending to the earth's surface, and is a field that involves complex and diverse areas of research. In this paper, we explain the process by which the Earth's upper atmosphere is ionized to form the ionosphere and introduce the characteristics of the ionosphere at low and mid-latitudes. In addition, we introduce the research that domestic researchers have participated in related to the ionosphere to date and hope that it will be used to promote exchange in the field of ionospheric research in the future.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.26.3-27
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• 2011

Formation of a steep plasma density gradient in the middle-latitude ionosphere during geomagnetic storms and the latitudinal migration of its location depending on the storm phase are suggested to be associated with the ionospheric signature of the plasmapause. We test this idea by using the satellite and ground observation data during the 11 April 2001 storm. The locations of the steep plasma density gradient identified by TOPEX/Poseidon (2001 LT) and DMSP (1800 and 2130 LT) satellites coincide with the ionospheric footprints of the plasmapause identified by the IMAGE satellite. This observation may support the dependence of the middle-latitude plasma density gradient location on the plasmapause motion, but does not explain why the steep density gradient whose morphology is largely different from the morphology of the middle-latitude ionization trough during quiet period is formed in association with the plasmapause. The ionospheric disturbances in the total electron content (TEC) maps shows that the steep TEC gradient is formed at the boundary of the positive ionospheric storm in low-middle latitudes and the negative ionospheric storm in middle-high latitudes. We interpret that the thermospheric neutral composition disturbance in the dayside is confined within the middle-high latitude ionospheric convection zone. The neutral composition latitudes and, therefore, the locations of the steep plasma density gradient coincide with the footprints of the plasmapause. The TEC maps show that the appearance of the steep plasma density gradient in the pre-midnight sector during the recovery phase is related to the co-rotation of the gradient that is created during the main phase.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.191-193
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• 2006

The ionospheric strom evolution process was monitored during the 18 August 2003 magnetic strom over China, through inversion of the ionospheric electron density from GPS observations. The temporal and spatial variations of the ionosphere were analysed as a time series of ionospheric electron density profiles. Results show that the main ionospheric effects of the storm over China under consideration are: the positive storm phase effect usually happens in the low latitudinal ionospheric; the negative storm phase effect occurs in the middle latitude, and the equatorial anomaly structure can be found as well.