Physics of auroral phenomena : proceedings of the 36th Annual seminar, Apatity, 26 February – 01 March, 2013 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2013. - 215 с. : ил., табл.

“Physics o f Auroral Phenomena”, Proc. XXXVI Annual Seminar, Apatity, pp. 143 -146, 2013 © Kola Science Centre, Russian Academy of Science, 2013 Polar Geophysical Institute INVESTIGATION OF THE POLAR CAP SOFT ELECTRONS FLUXES' INFLUENCE ON THE LATITUDINAL VARIATIONS OF THE IONOSPHERE TOTAL ELECTRON CONTENT AND PEAK F2-LAYER ELECTRON DENSITY M.G. B o tov a1, A .A . N am galadze1, B.E. Prokhorov 2,3 Murmansk State Technical University, Murmansk, Russia, e-mail: botovamg@gmail.com Helmholtz Centre Potsdam, GFZ German Research Centre fo r Geosciences, Telegrafenberg, 144734 Potsdam , Germany University Potsdam, Applied Mathematics, Interdisciplinary Centerfor Dynamics o f Complex System (DYCOS), 14476 Potsdam, Germany The paper presents the results of the investigation of the polar cap soft electrons fluxes' influence on the latitudinal variations o f the ionosphere total electron content (TEC) and peak F2-layer electron density (NmF2).The results of the TEC and NmF2 modeling were compared with the data obtained from the empirical ionospheric model IRI-2007 and Global Ionosphere Maps (GIM) of the TEC. It was shown that to improve an agreement between the model case and observation it is necessary to increase the intensity of the "polar rain" for an order. Introduction The aim o f the present work is to study of the polar cap soft electrons fluxes'("polar rain") influence on the latitudinal variations the total electron content(TEC) and peak F2-layer electron density (NmF2). The "polar rain" is a flux of low energy (from a few to a few hundred eV) electrons precipitating in the polar caps. The "polar rain" was discovered and named by Winningham and Heikkila [1]. The "polar rain" electrons access the polar cap by open field lines. The electrons with such energies effectively spend it on the ionization at F2-region altitudes. As a result, the electrons density at the peak F2-layer and TEC in the regions of the precipitations may increase. The model calculations by using the model UAM show that the polar caps F2-layers have the very low density of the electrons, and that is in contrast to the results of the empirical model IRI-2007 and TEC GPS observations. In this paper, we tried to estimate "polar rain", fluxes' required to eliminate the above mentioned difference. Model calculations The computer modeling of the NmF2 and TEC latitudinal variations was performed using the global three- dimensional self-consistent numerical model of the Upper Atmosphere of the Earth (UAM) [2]. UAM describes the thermosphere, ionosphere, plasmasphere and inner magnetosphere of the Earth as a unite system. It covers the altitude range from 60-80 km up to the geocentric distance of 15RE. UAM calculates the concentrations of the main neutral and charged components o f the upper atmosphere, the temperature of neutral, ion and electron gases, the velocities o f charged and neutral particles by numerical integration of quasi-hydrodynamic equations (continuity, momentum and heat balance), as well as equation for the electric potential of the magnetospheric, thermospheric (dynamo) and seismogenic origin. The UAM model calculations o f TEC and NmF2 have been performed with using the empirical thermospheric NRLMSIS-00 model [3] for neutral components (UAM-TM). The model calculations have been carried out for equinox and solstice conditions and different levels of solar activity (FI 0,7 ~ 90 and FI 0,7 ~ 180). In this paper, the model calculations used the following polar cap soft electrons fluxes': 1) according to [4], 2) and increased for an order. The latitudinal variations o f the TEC and NmF2 were analyzed for the meridional section 15-03 of the magnetic local time (MLT). The results o f the model calculations have been compared with the empirical model IRI-2007[5] and GIM of the TEC provided by the NASA in IONEX format derived from IGNSS network data [ 6 ]. Fig. 1 shows the latitudinal variations o f the peak F2-layer electron density (NmF2) calculated by version of UAM-TM and empirical model IRI-2007 for the magnetic meridian 15-03 MLT. Abstract 143