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 fAuroral P h enom en a", Proc. XXXIII A n n u a l Sem inar, A patity, pp. 1 0 9 -1 1 2 , 2011 © Kola Science Centre, Russian Academy of Science, 2011 Polar Geophysical Institute DISTURBANCES OF HELIOGEOPHYSICAL PARAMETERS DISPLAYING IN THE MAXIMUM OBSERVED FREQUENCIES ON IONOSPHERIC OBLIQUE SOUNDING TRACES 0 .M . Barkhatova ’’2, N .A . Barkhatov S.E. Revunov 1 (1) Nizhniy Novgorod State Pedagogical University, Nizhniy Novgorod, Russia (2) Nizhniy Novgorod State Universityfo r Architecture and Civil Engineering, Nizhniy Novgorod, Russia Abstract. The influence of heliogeophysical parameters on maximum observed frequencies (MOF) variations on short-wave (SW) ionospheric traces of oblique sounding Inskip - Rostov-on-Don and Cyprus - Rostov-on-Don in December 2006 r, traces Inskip - Rostov-on-Don, Norilsk - Rostov-on-Don and Irkutsk - Rostov-on-Don in March, 2007 is executed. The key parameters of the interplanetary space which have the greatest influence on MOF variations on subauroral, mid-latitude and low-latitude ionospheric traces are established. The analysis of received results shows that changes of Interplanetary Magnetic Field components By and Bz are revealed in MOF of Norilsk - Rostov-on-Don subauroral trace. At middle latitude traces Inskip - Rostov-on-Don and Irkutsk - Rostov-on-Don the influence of Bx, By and Bz Interplanetary Magnetic Field components is more evident. At low-latitude trace Cyprus - Rostov-on-Don the influence of Interplanetary Magnetic Field module and its components By and Bz is marked. Solar wind density and velocity are revealed in MOF variations on all traces. 1. Introduction The studying o f the maximum observed frequencies at SW oblique sounding traces is the effective tool for diagnostics o f ionosphere condition. Analysis of MOF variations on various ionospheric oblique sounding traces helps to reveal interplanetary space parameters which have the greatest influence on variations of ionospheric density both in high and middle latitudes. It is well known that on location of plasma ring and main ionospheric trough changes of ionospheric density has appreciable influence at high latitudes. Moving of these structures for one's turn is substantially determined by Solar wind velocity and by quantity and orientation of Interplanetary Magnetic Field components By and Bz [Kolesnik ct al., 2001; Mikhailov et al., 1998; Yokoyama et al., 1998; Ahmed and Sagalin, 1973; Caan, 1980]. The middle and low latitude ionosphere basically exists due to x-ray and ultra-violet ionizing radiation. However a displaying of interplanetary space parameters in density variations at these latitudes must not map out. The basic purpose o f current research is the establishment of key interplanetary space parameters which have the greatest influence on the maximum observed frequencies of subauroral trace Norilsk - Rostov-on-Don, mid-latitude traces Inskip - Rostov-on-Don and Irkutsk - Rostov-on-Don and low-latitude trace Cyprus - Rostov-on-Don. 2. Used data The influence o f interplanetary space parameters on variations of maximum observed frequencies has been carried out for subauroral, mid-latitude and low-latitude SW ionospheric oblique sounding traces Inskip - Rostov-on-Don and Cyprus - Rostov-on-Don in December 2006 r, Inskip - Rostov-on-Don, Norilsk - Rostov-on-Don and Irkutsk - Rostov-on-Don in March, 2007. Solar wind (PSW) and Interplanetary Magnetic Field (IMF) parameters have been taken from spacecraft ACE for times corresponding to the specified intervals. The data of x-ray radiation have been taken from spacecraft GOES for wavelengths range 1-8 Ang (XL) and 0.5-3 Ang (XS). The removal of a daily variation from initial data at each of considered traces is made. It allows us to study only MOF disturbances. For this purpose all initial MOF sequences has been approximated by Gauss function: / = al ■ exp( - ( ( * - i>,) / c,)2)+... + a, ■ exp( - ( ( * - bt ) / cg)2) Further calculated values of Gauss function were subtracted from initial sequence. The received result (Rez F) represents so-called MOF "residuals" which contain only MOF disturbances (DMOF). Further in this work under MOF it will be meant Rez F values (DMOF). The example of daily variations removal on Fig. 1 for trace Inskip - Rostov-on-Don on March, 16-31 2007 is represented. Here the top panel is the initial MOF data approximated by Gauss function and the bottom panel is MOF "residuals" (Rez F). 109