Physics of auroral phenomena : proceedings of the 34th Annual seminar, Apatity, 01 - 04 March, 2011 / [ed.: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 231 с. : ил.

Fig-3 demonstrates the F2-layer peak electron density and height calculated by the UAM-T and UAM-MSISE- HWM versions for the geodetic meridian of 285° in comparison with the IRI-2001 data. In Fig.3 the NmF2 diurnal variations calculated by the IRI-2001 for the geomagnetic latitudes o f -50° and -55° have the maximum values at 22- 24 LT. The hmF2 diurnal maximum of about 350 km is produced by the IRI-2001 for the same hours. The UAM versions give the NmF2 maximum at 19-21 LT. The UAM-MSISE-HWM results agree better with the IRI-2001 for both NmF2 and hmF2 values. Longitudinal variations o fthe electron density enhancements in the summer night-time ionospheric F2-layer: numerical modeling 23.12.1985 X = 285° hmF2, km * / ф= -40° <p= -45° Ф = -50° i | i i | i i | i i | i i j i i | i i j i i | i i | i i | I i | i i | Ф = -55° 18 21 24 3 LT, hours — IRI -2001 UAM-T I I I I I I I I I II I I I | I 'I | II j' I I | I I | IT |"I I | IT 18 21 24 3 6 LT, hours ......... UAM-MSIS-HWM Fig.3. LT variations of NmF2 and hmF2 at geodetic longitude of 285° at several geomagnetic latitudes calculated by the UAM versions for December 23, 1985 in comparison with the IRI-2001 data. 4. Conclusions We have reproduced the Weddell Sea Anomaly by the global theoretical 3D Upper Atmosphere Model. The UAM gives similar WSA patterns in the versions taking into account the non-coincidence of the geodetic and geomagnetic axes. These patterns reproduce the corresponding IRI-2001 foF2 distribution qualitatively. The phenomenon is 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 at different longitudinal sectors. 145