Physics of auroral phenomena : proceedings of the 40th annual seminar, Apatity, 13-17 March, 2017 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2017. - 143 с. : ил., табл.

Auroral oval and outer electron radiation belt The dependence (1) yet is not wholly explained and obtaining of its explanation may be connected with definite modification of the standard description of the role of auroral processes in the magnetospheric dynamics. In this paper we try to shortly summarize the main findings demonstrating the deep connection of auroral processes and outer radiation belt formation. We also try to formulate problems, which require solution. 2. Auroral oval mapping One of the main reasons, which oppressed the study of auroral processes as the source o f outer radiation belt formation is the inadequate auroral oval mapping connected with overstretching of magnetic field models with pre-defined geometry of current systems. First such model was created by Alexeev and Shabansky [1972]. Fig. 8 of there paper shows zero radial thickness of the region of plasma sheet mapping near noon. However, from the first auroral oval observations (see, for example, Feldstein et al. [2014]) it was known, that auroral oval has thick structure near noon. The existence of thick auroral oval near noon is supported by multiple results of auroral imagers (DE-1, Polar, IMAGE ets.) and models of auroral precipitations NOAA ( http://www.swpc.noaa.gov/pmap/) , OVATION ( http://sd- www.jhuapl.edu/Aurora/ovation_prime) and АРМ ( http://apm.pgia.ru/) . АРМ model classifies the regions o f the auroral oval according to the kinds of electron precipitations as follows: the auroral oval precipitation region (AOP), the diffuse auroral zone (DAS) located to the equator from the AOP, and the soft diffuse precipitation zone (DAS) located to the pole from AOP. Starkov et al. [2003] showed that AOP statistically coincides with Feldstein auroral oval. Plasma sheet like particle fluxes are observed around the Earth till magnetopause [ Antonova et al., 2013,2014a], which shows the possibility o f auroral oval mapping to the ring like structure. To verify this suggestion Antonova et al. [2014b, 2015] analyzed the auroral oval mapping to the equatorial plane using АРМ model and results of observations of THEMIS mission. They used method of morphological mapping, comparing values of plasma pressure at the auroral latitudes and at the equatorial plane. The validity of the condition of magnetostatic equilibrium was suggested. They show that most part of auroral oval does not map to the plasma sheet. It is mapped to the surrounding the Earth plasma ring. Transverse currents in this ring are the outer part of the ring current. Fig. 2 illustrates this statement. Fig. 2a shows ion pressure distribution in the oval precipitation region (AOP) for quite geomagnetic conditions (AL=-100 nT, Dst=-5 nT) in accordance with Vorobjev et al. (2015) model of ion precipitations. Dots show boundaries of AOP in accordance with АРМ model. It is possible to see that ion pressure in AOP exceeds 0.2 nPa. This value is larger than typical values o f plasma sheet full pressure. Fig. 2b shows plasma pressure distribution at the equatorial plane in accordance with THEMIS data. It is possible to see that isoline />=0.2 nPa surround the Earth. Existence o f field-aligned potential drops in inverted V structures decrease ion pressure at the ionospheric altitudes in comparison with the equatorial plane. This effect leads to decrease of ion pressure at auroral altitudes in comparison with the equatorial plane. Therefore, Fig. 2 clearly shows the quite time auroral oval cannot map to the plasma sheet. It is mapped to the surrounding the Earth plasma ring. Kirpichev et al. [2016] showed that equatorial boundary o f the nightside quite auroral oval is mapped to geocentric distance ~7Re and polar boundary at geocentric distance ~10Re. 10.0 о a. с 1)' 1.0 5 i a. ^ о e о CL 0.1 15 10 5 0 -5 -10 -15 Xsm- a b Figure 2. An example of comparison of ion pressure in AOP in accordance with Vorobjev et al. [2015] (a) with pressure distribution at the equatorial plane, obtained using data of Themis mission for quite geomagnetic conditions AL=-100 nT, Dst=-5 nT. Mapping the equatorial boundary o f the quite auroral oval to geocentric distance ~7Re is in a good agreement with the first auroral arc brightening at the equatorial boundary of the oval (see Akasofu [1964] and multiple results o f later works) and position of the dispersionless injection boundary [Lopez et a l, 1990; Spanswick et al., 2010]. Position of the polar boundary at geocentric distance ~10REis in a good agreement with the position of the outer boundary of the ring current [Kirpichev and Antonova, 2014]. 7