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.

LONG -TERM VAR IAT ION S OF ENERGET IC ELECTRON S AT LOW ALT ITUDES V .L. Petrov, M.I. Panasyuk ( Skobeltsyn Institute o f Nuclear Physics o f Moscow State University, Moscow, Russia) Abstract. The charged particles under the Radiation belts at the small altitudes are few studied till now. The wide- used radiation models do not take into account such fluxes. The long-term variations of the electrons with energies of hundreds keV at L < 2 are discussed. The variations were studied using the NOAA POES series satellites data. These satellites are operating at ~ 800-km circle polar orbits. The variations o f the average electron flux for more than 10 years (1998-2009) are presented. The new effects were revealed at near-equatorial and middle-latitudinal regions: - Seasonal semiannual variation of the quasi-trapped electrons flux; - The average flux of the quasi-trapped electrons considerably increased in the previous solar cycle. The electron flux variations were compared to different magnetospheric parameters. The results o f the comparison are discussed below. Introduction This paper analyzes experimental data about the long-term variations o f electron fluxes under the Radiation Belts. Charged particles’ formations are observed at near-equatorial, low and middle latitude regions at L-values < 2. Electron flux enhancements under the Radiation Belts at L < 2 have been observed since early 1978 in a number of space experiments (Nagata et a l, 1988; Voss et a l, 1980). Later these fluxes were studied and some of their spatial and spectral characteristics were described in (Grigoryan et a l, 2008). Nevertheless many questions concerning the structure, dynamics and sources of these electron flux formations in this region still remain open. Experimental data We need to study the long-term variations of the charged particles at the bottom of the inner radiation belt to understand completely their dynamics. The only way to make the continuous series of data is to use similar instruments in similar conditions for all the period. In the terms of space experiment it means either long living satellite or the series of identical satellites on the same orbits. Polar Operational Environmental Satellites o f NOAA agency satisfy these conditions. At the table below one can see some details o f POES missions. These satellites produce a continuous row of charged particles monitoring data since 1998 till nowadays ( http://www. oso.noaa.sov/poes/index.him and further on the links). “P hysics o f Auroral P h en om en a ”, Proc. XXXIII A n n u a l Sem inar, A patity, pp. 144 - 146, 2011 © Kola Science Centre, Russian Academy of Science, 2011 Table 1. NOAA series satellites. № Satellite index Years of operation Orbit details Description 1 NOAA TIROS-N 1978-1981 Out of orbit 2 NOAA POES-O 6 1979-1986 Out of orbit Not all data 3 NOAA POES-07 1981-1985 Out of orbit Not all data 4 NOAA POES-O 8 1983-1985 Out of orbit Not all data 5 NOAA POES-10 1986-1991 Out of orbit 6 NOAA POES-11 1988-2002 Out of orbit Not all data 7 NOAA POES-12 1991-2002 Out o f orbit Not all data 8 NOAA POES-14 1995-2004 Out of orbit 9 NOAA POES-15 Launched in 1998 807 km (curr.), 98.5° Operating 10 NOAA POES-16 Launched in 2001 849 km (curr.), 99.0° Operating 11 NOAA POES-17 Launched in 2002 810 km (curr.), 98.7° Operating 12 NOAA POES-18 Launched in 2005 854 km (curr.), 98.7° Operating 13 NOAA MetOp-2/А Launched in 2006 817 km (curr.), 98.7° Operating 14 NOAA POES-19 Launched in 2009 870 km (curr.), 98.7° Operating 144 Polar Geophysical Institute