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Vol. 8 (2005 year), No. 1

Knyazeva M.A., Namgaladze A.A.
Mathematical modelling of forming the night middle-latitude maxima of the electron density in the F2-region of the quiet middle-latitude ionosphere and in the Earth plasmasphere

The relative role of the thermospheric wind and electromagnetic drift in forming the night middle-latitude maxima of the electron density has been investigated for the quiet geomagnetic conditions by using the global numerical upper atmosphere model (UAM). It has been shown that the thermospheric wind creates these maxima, and the electromagnetic drift influences on the form and latitude location of the high-latitude side of the higher electron density regions, the latter depends on the value of the electromagnetic drift velocity. It has been found that appreciable UT- and MLT-effects become apparent in the latitudinal location, form and structure of these regions. The night middle-latitude maxima are clearly seen in the Northern Hemisphere near 00:00 UT and in the Southern Hemisphere - near 18:00 UT. The maxima are shifted to the more low latitudes when getting from the evening hours to the postmidnight ones.

(in Russian, стр.12, fig. 12, tables. 0, ref 10, Adobe PDF, Adobe PDF 1700 Kb)

Vol. 13 (2010 year), No. 4

Knyazeva M.A., Zubova Yu.V., Namgaladze A.A.
Numerical modelling of the Weddell Sea Anomaly in behaviour of the ionospheric F2-region

The morphology and mechanism of the Weddell Sea Anomaly (WSA) forming has been investigated by using the global numerical model of the Upper Atmosphere Model and empirical model of the ionosphere IRI-2001. It has been shown that both models reproduce WSA in the summer southern hemisphere in longitudinal sector 255-315?E. It has been found that the analogous WSA longitudinal variation of the electron density takes place in the summer northern hemisphere in longitudinal sector 75-135?E. It has been shown that both phenomena are caused by the non-coincidence of the geomagnetic and geodetic axes which produces the difference in vertical velocities of the ion transfer by the thermospheric wind action in the western and eastern longitudinal sectors.

(in Russian, стр.10, fig. 6, tables. 0, ref 32, Adobe PDF, Adobe PDF 0 Kb)

Vol. 15 (2012 year), No. 3

Knyazeva M.A., Romanovskaya Yu.V., Namgaladze A.A.
Numerical modeling of the electron density enhancements in the night-time ionospheric F2-layer

The middle-latitude enhanced electron density regions (EEDRs) in the night-time ionospheric F2-layer have been investigated using the global numerical Upper Atmosphere Model (UAM) and the empirical ionospheric model IRI-2001. The mechanism of formation, seasonal and latitudinal-longitudinal variations of the EEDRs has been studied. It has been shown that two types of the EEDRs exist on the geomagnetic foF2 maps: 1) winter type with maxima in the latitudinal and diurnal foF2 variations and 2) summer type with the maximum in the latitudinal variation only. Formation of both types of the EEDRs is explained by the corresponding seasonal variations of the thermospheric wind. The physical mechanism of the EEDRs forming is based on the joint action of the plasma flows from the plasmasphere and the neutral wind inducing transportation of the ionospheric plasma along the geomagnetic field lines. The Weddell Sea Anomaly and the analogous phenomenon observed in the Northern Hemisphere have been explained.

(in English, стр.14, fig. 7, tables. 0, ref 56, Adobe PDF, Adobe PDF 0 Kb)