Место издания:Полярный геофизический институт Апатиты
Первая страница:45
Аннотация:The ionization of the upper atmosphere is mainly caused by the X-ray and UV/EUV electromagnetic radiation from the Sun. At the same time, subauroral and auroral ionization is significantly contributed by corpuscular fluxes. Due to the stronger connection to the magnetosphere, the subauroral and auroral ionosphere noticeably differs from the midlatitude ionosphere. The ionization rate in the midlatitude ionosphere is almost fully determined by short-wave solar radiation whereas important role in ion production in the high latitudes is played by particle fluxes from the magnetosphere which are even the only source of ionospheric ionization during polar night. Ionization produced by the corpuscular fluxes from the magnetosphere is typically small compared to the ionization by the electromagnetic radiation; however, its contribution can still be noticeable during the sufficiently strong geomagnetic storms and in the nighttime when ionization of the ionospheric plasma by solar electromagnetic radiation is inefficient.
Our presentation is devoted to studying the ionospheric effects of particle precipitation based on radio tomographic (RT) imaging of the ionosphere. Particular attention is focused on the results of RT reconstructions of the ionosphere which were obtained in the different years at the receiving stations of the Svalbard–Murmansk–Moscow Russian RT chain. We identified particle precipitation events based on the satellite particle flux measurements by the DMSP satellites. We present and discuss the examples of the comparison of the ionospheric RT images with the fluxes of precipitating particles measured by DMSP satellites as well as with the auroral oval data.
The RT images of the ionosphere show multi-extremum patterns of ionization with the presence of wavelike disturbances on the spatial scales from dozens to hundreds kilometers during the severe geomagnetic storms. The spatial scales of corpuscular precipitation in these cases widely varied from a few to ten degrees in latitude. An overall qualitative agreement is observed between the spatial structure of the corpuscular ionization in the RT images and the latitudinal distributions of the fluxes of precipitating particles.
The work was supported by the Russian Foundation for Basic Research (grants 17-05-01250 and 19-05-00941)