Physics of auroral phenomena : proceedings of the 33rd Annual seminar, Apatity, 02 - 05 March, 2010 / [ed.: A.G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 206 с. : ил.

“P hysics o f Auroral P henom ena”, Proc. XXXIII A n n ual Sem inar, Apatity, pp. 121 - 124, 2011 © Kola Science Centre, Russian Academy of Science, 2011 Polar Geophysical Institute TESTING OF THE UPPER ATMOSPHERE MODEL U S ING THE EMPIR ICAL IONOSPHERIC MODELS M.A. Knyazeva1, A.A. N am galadze1, M.G. Deminov2, K.E. Beloushko1, M .A. G rigorieva1, S.V. Porubova1 1 Murmansk State Technical University, 13 Sportivnaya Str., Murmansk, 183010 2 Institute o f Terrestrial Magnetism, Ionosphere and Radio Wave Propagation o f N. V. Pushkov, Troitsk, Moscow Region, Russia, 142190 e-mail: mariknyazeva@yandex.ru, namgaladzeaa@mstu.edu.ru Abstract. The seasonal variations o f the quiet ionospheric F2-layer have been modeled by using different versions of the numerical global Upper Atmosphere of the Earth Model (UAM). The results of foF2 and hmF2 calculations have been compared with data of two empirical models: 1) IRI-2001 and 2) Q-F2 developed by Deminov et al. [2009]. All versions of the model calculations show a better agreement for winter solstice and spring equinox in the northern hemisphere. There are the maximal differences between all model results and experimental data in the night-time sector. It has been shown that these differences are related with the theoretically calculated variations of the thermospheric circulation and neutral gas composition. Introduction In order to investigate the ionospheric F2-layer behaviour during disturbed periods the ionospheric parameters (the F2-layer critical frequency (foF2), the maximal electron density (NmF2) and the height of the F2-layer peak ( hmF2 )) are estimated relative to quiet background values. The reliability and interpretation o f the obtained results depend on a method used for background values calculation. The empirical model Q-F2 developed by Deminov et al [2009] calculates the diurnal variations of the background values o f foF2. The model was approved by using the data o f the middle-latitudinal ionosonde stations Slough (52.5°N, 104°E) and Irkutsk (51.5°N, 359.4°E) for the periods of 1958- 1992 and 1958-1995 respectively [Deminov et al., 2009]. It was shown that the Q-F2 model reproduced qualitatively and quantitatively the observed regular seasonal and annual variations of the quiet ionospheric F2-layer. In this work we present the results of testing of the global numerical three-dimensional time-dependent Upper Atmosphere Model (UAM) [Namgaladze et al., 1998] from the point of view of simulating the seasonal variations of the quiet ionospheric F2-layer by this model. Model calculations We have tested three versions of the UAM: 1) with the theoretically calculated thermosphere parameters (UAM-TT in abbreviated form); 2) with the empirical thermospheric NRLMSISE-00 model [Picone et al., 2002] (UAM- MSIS); 3) with the NRLMSISE-00 and the empirical model of the horizontal neutral wind HWM-93 [Hedin et al., 1996] (UAM-MSIS-HWM). The UAM versions differ from each other in the method of the thermospheric three- dimensional circulation and neutral gas composition calculations. In the UAM-TT version the thermospheric composition and neutral wind velocity are calculated by the numerical integration of the continuity, momentum and heat balance equations for the neutral atmosphere. In the UAM-MSIS version the neutral composition and circulation are calculated by using the MSIS model. In the UAM-MSIS-HWM version the composition is calculated by using the MSIS model and the horizontal neutral wind velocities are calculated by using the HWM. The vertical component of the thermospheric wind velocity is calculated by numerical solution o f the continuity equation for the neutral mass density. The diurnal variations of foF2 and hmF2 over Slough and Irkutsk were calculated by all UAM versions for three selected quiet days representing conditions near the winter and summer solstices and spring equinox under the middle solar activity: December 16,1992 (Fl0,f= 146.0), July 15,1983 {F10.f= 124.6), April 16, 1988 (F;a7=147,6). Two top plots of the Figures 1-3 present the calculated foF2 and hmF2 diurnal variations over Slough. The UAM results were compared with the data of the empirical model Q-F2 [Deminov et al., 2009] and the ionospheric model IRI-2001 [Bilitza D., 2001]. The third and fourth plots of the Fig. 1-3 present the corresponding variations of the northward neutral wind VM and the ratio of the О and N, concentrations at the altitude o f 300 km. The plots are used to analyze possible reasons of the disagreement between the UAM results and the empirical models data. The foF2 and hmF2 variations calculated by the UAM, Q-F2 and IRI-2001 show a good agreement for winter solstice and spring equinox at first twenty four hours. The UAM-MSIS version has a better agreement with the data of the empirical models. 1 2 1