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| Titel |
LION: A dynamic computer model for the low-latitude ionosphere |
| VerfasserIn |
J. A. Bittencourt, V. G. Pillat, P. R. Fagundes, Y. Sahai, A. A. Pimenta |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 25, no. 11 ; Nr. 25, no. 11 (2007-11-29), S.2371-2392 |
| Datensatznummer |
250015947
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| Publikation (Nr.) |
 copernicus.org/angeo-25-2371-2007.pdf |
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| Zusammenfassung |
| A realistic fully time-dependent computer model,
denominated LION (Low-latitude Ionospheric) model, that simulates the
dynamic behavior of the low-latitude ionosphere is presented. The time
evolution and spatial distribution of the ionospheric particle densities and
velocities are computed by numerically solving the time-dependent, coupled,
nonlinear system of continuity and momentum equations for the ions O+,
O2+, NO+, N2+ and N+, taking into account
photoionization of the atmospheric species by the solar extreme ultraviolet
radiation, chemical and ionic production and loss reactions, and plasma
transport processes, including the ionospheric effects of thermospheric
neutral winds, plasma diffusion and electromagnetic E×B plasma drifts. The Earth's magnetic field is represented by a tilted
centered magnetic dipole. This set of coupled nonlinear equations is solved
along a given magnetic field line in a Lagrangian frame of reference moving
vertically, in the magnetic meridian plane, with the electromagnetic E×B plasma drift velocity. The spatial and time distribution
of the thermospheric neutral wind velocities and the pattern of the
electromagnetic drifts are taken as known quantities, given through
specified analytical or empirical models. The model simulation results are
presented in the form of computer-generated color maps and reproduce the
typical ionization distribution and time evolution normally observed in the
low-latitude ionosphere, including details of the equatorial Appleton
anomaly dynamics. The specific effects on the ionosphere due to changes in
the thermospheric neutral winds and the electromagnetic plasma drifts can be
investigated using different wind and drift models, including the important
longitudinal effects associated with magnetic declination dependence and
latitudinal separation between geographic and geomagnetic equators. The
model runs in a normal personal computer (PC) and generates color maps
illustrating the typical behavior of the low-latitude ionosphere for a given
longitudinal region, for different seasons, geophysical conditions and solar
activity, at each instant of time, showing the time evolution of the
low-latitude ionosphere, between about 20° north and south of the
magnetic equator. This paper presents a detailed description of the
mathematical model and illustrative computer results. |
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