E.V. Kononovich (Sternberg Astronomical Institute of Moscow University, 119899 Moscow, Russia)

The relative numbers of sunspots are known for a rather long period of time. Their continuous observations cover about two and a half centuries including 24 complete 11-year cycles. R.Wolf has made a lucky suggestion to introduce them as a solar activity index by adding to the total number of sunspots the tenfold number of the groups formed by them. Up to now the Wolf numbers have the highest value of their citation index. Their sequence incorporates a large amount of information not yet exhausted. The main fact is that it is non stationary: the most pronounced frequency of its spectrum (about 0.6 rad/year corresponding to 11 year period) is rather wide and modulated by several long-term oscillations. This frequency is the first harmonic of physically more significant 22-year cycle reflecting the regular change of the solar magnetic field. The nonstationary character of the solar activity produces difficulties for solar activity predictions. Nevertheless many efforts have been made to obtain sound prognosis. Forecasts for the new coming cycle 23 lead to ambiguity due to the fact that the current pattern of solar activity is possibly near to its critical point. There are two different versions of the next cycle forecast: the high prognosis (W~200) and the low one (W~100). We have elaborated a method to forecast simultaneously the both cycles 23 and 24. Assuming this result we can find out the current maximum of the long-term cycle (so called 80-100 year cycle) has occurred in 1981. This means that we have just passed it and begin to exercise the long-term cycle fall. It is important to connect this event with the solar irradiance variations recently observed e.g by SOHO experiment especially because of the fact that the solar activity is strongly connected with the geomagnetic and ionosphere activity. During the last decades the connection with parameters of the lower atmosphere (which are very important to the mankind) also was proved. This relationship, however, turned out to have a rather complicated pattern strongly depended upon region, season, latitude, solar cycle phase etc. We have shown that the solar activity influence interferes with the circulation form transformations. The importance of considering the better determined F_10.7 is emphasised. A more simple formula connecting the both indices is given.

A.I. Podgorny, I.M. Podgorny (Lebedev Institute of Physics RAN, Moscow 117 924, Russia, Institute for Astronomy RAN, Moscow, 109 017, Russia)

Many observations demonstrate strong dependence of phenomena in different parts of solar-terrestrial environments on explosive events in the Sun (flares, solar mass ejections). For investigations of these relationships it is very important to know when and where a solar flare should occur. X-ray images show that primary solar flare energy release in the solar corona above an active region. The mechanism of energy accumulation in the current sheet above the active region has been investigated. It is shown that the initially stable current sheet can be transferred into an unstable state during the evolution, and fast energy release occurs. The flare model based on this theory permits to understand all solar flare events: fast energy release, its transfer to the chromosphere, high energy particles acceleration, mass ejection, field-aligned currents and post flare loops production at al. The condition of current sheet formation has been investigated in the 3D MHD numerical experiment, including current sheet evolution above an real active region. The different modes of photospheric disturbances (up flow velocities, magnetic tube flowing up at al.) course the current sheet creation. The PERESVET program is used. It is shown that solar flare appearance can be predicted from numerical simulation of active region development.

K.I. Nikol'skaya, T.E. Val'chuk (Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of Russian Academia of Sciences, 142092, Troitsk of Moscow Region, e-mail: solter@charley.rssi.ru)

An alternative solar wind (SW) and solar corona (SC) concept suggested in [1,2] is considered in the light of new experimental data. According to this concept, both SW and SC are a result of the interaction between the initial solar high speed plasma outflow with coronal magnetic fields. A velocity model of inner fast SW V(r) (within 1Rsun < r < 1 AU) was computed using outer SW measurement data by Ulysses (Vsw = 750 km/s at r>1 AU). In contrast to standard SW acceleration models this model reveals sharp deceleration of SW streams from 1000 to 760 km/s between 1 and 7 solar radii with following fall to ~750 km/s. Such a velocity model is in a very good agreement with the new results of Helios [3] in situ measurements and EISCAT & VLBA [4] solar wind velocity determinations by the technique of radio scintillation observations that is considered as convincing argument in favour of an alternative solar wind concept under investigation.

[1] Nikol'skaya K.I. & Val'chuk T.E. Cosm.research (Russ.),1996, V.34, N6, P.415

[2] Nikol'skaya K.I. & Val'chuk T.E. Physics of auroral phenomena, 20 Annual Seminar, Abstracts, 1997, P.13.

[3] Schwenn R., Montgomery M.D., Rosenbauer H. et al. J.Geophys.Res. 1978. V.83, A3, P.1011.

[4] Grall R.R., Coles W.A., Klinglessmith M.T. et al. Letters to Nature. Nature. 1996. V.371. P.429.

G.A. Bazilevskaya, M.B. Krainev, V.S. Makhmutov (Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Prospect, 53, Moscow, 117924, Russia, krainev@fiand.msk.su)

The double- (or multy-) peak structure in many solar characteristics during solar maximum epochs was revealed for the first time by M.N.Gnevyshev in 1960s and studied later by several authors. However underlying physical processes still remain obscure. It was found that the double peak structure is actually connected with a short lasting (~6 - 18 months) quietness in occurrence of powerful solar flares, coronal mass ejections (CMEs), consequent interplanetary disturbances, galactic cosmic ray characteristics etc., that take place near the sunspot maximum. The phenomenon was named "Gnevyshev gap" (Storini and Pase, 1995) emphasizing the interest to the nature of dips between peaks of solar activity. It is important that the gaps occur during periods of the solar polar magnetic field reversal. In our opinion, there is a cause-and-effect relationship between the two phenomena.

The interplanetary parameters (solar wind speed and density, the strength and direction of the regular magnetic field) respond to the decreasing in the transient activity on the Sun during Gnevyshev gaps by the changes in magnitude and/or in the degree of fluctuation. Since the interplanetary conditions influence the magnetospheric processes, the Gnevyshev gap effect has to be present in the magnetosphere too. In this talk we examine behaviour of magnetospheric indices during epochs of solar activity maximum and compare it with parameters of interplanetary medium and characteristics of solar polar magnetic field reversals.

O.N. Savina (State Technical University, 24 Minina st., Nizhny Novgorod, 603600, Russia)

We study peculiarities of propagation of atmospheric waves in the solar transition region. Our investigations are based on a dispersion relation of surface waves in a two-layer model approximation with different temperatures.

These results are useful for interpretation of experimental data of the solar atmosphere.

Acknowledgments. This work is supported by the Russian Foundation of Fundamental Research grant No. 96-05-64277.

P.V. Klshcha and l.V. Dmitrieva (Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, 142092, Troitsk, Moscow region, Russia)

Long series of sunspot numbers and indices of geomagnetic activity from 1868 to 1990 have been examined by the method of cross-correlation analysis. Secular variations of the 23-year running correlation between the sunspot numbers and the parameters of geomagnetic activity with a characteristic period of about 50 years have been obtained. The selected secular variations are due to long-term variations of the time shift between indices of solar and geomagnetic activity from 1 to 3 years. These variations are well defined for the short-term part of spectrum of the datasets under investigation with periods not greater than 11 years and are not defined for long-term part of the spectrum.

По данным о спектрах полуночных полярных сияний обс. Лопарская рассматриваются интенсивности зеленой и красной линий и их отношений во время геомагнитных бурь. Получены зависимости этих величин от скорости и южной компоненты ММП для случая стационарных потоков от корональных дыр и нестационарных вспышечных потоков солнечного ветра. Отличие спектральных характеристик полярных сияний для разных типов потоков солнечного ветра наиболее ярко проявляется в отношении интенсивностей зеленой к красной эмиссий, характеризующее жесткость высыпающихся в атмосферу электронов. В случае стационарных потоков характерны высыпания в атмосферу жестких электронов, вызывающих полярные сияния с I557.7/I630.0 < 0.4. Во время нестационарных потоков в атмосферу высыпаются более мягкие электроны с широкополосным спектром и I557.7/I630.0 > 0.8. Данный вывод, что разные типы потоков солнечного ветра определяют принципиально различные спектры высыпающихся в ионосферу частиц, подтверждается по данным измерений высотных профилей электронной концентрации. При одинаковых величинах Ne в Е области, в области F профили резко расходятся, так что в максимуме F2 слоя величина электронной концентрации для нестационарных потоков значительно (более чем в два раза) превышает эту величину для стационарных.

E.V. Vashenyuk, V.V. Pchelkin (Polar Geophysical Institute, Apatity, Russia)

The ground-level enhancement (GLE) of the relativistic solar cosmic rays (RSCR) during the 29.09.1989 event was not only the largest for the last 40 years but was marked also by a number of unusual characteristics, such as two maximum intensity profile and complicated behavior of the rigidity spectrum and anisotropy. Characteristics of RSCR in this event were studied by data of the worldwide neutron monitor network together with their asymptotic direction of approach calculations. These asymptotic direction were calculated by means of numerical integrations of motion equations of primary CR protons in the modified Tsyganenko 89 magnetospheric model. An increase effect due to RSCR at the earth surface has been modeled by using tentative forms of rigidity spectra, pitch-angle distributions and anisotropy axis directions. The exact values of these quantities could be obtained by fitting calculated with their suggested forms increase effects at the earth surface to observed ones by the neutron monitor network. A hypothesis about bidirectional RSCR anisotropy at the late phase of the event has been checked. The last one suggests that the IMF during the 29.09.1989 GLE had a shape of giant loop with its both ends rooted into the Sun.

V.V. Pchelkin, E.V. Vashenyuk, O.M. Ostapenko, Yu.P. Maltsev

A.A. Lubchich (Polar Geophysical Institute, Apatity, Russia)

Ideal MHD approximation has been used for consideration of transmission of the small amplitude forward or backward fast magnitosonic wave having an arbitrary incident angle trough the fast shock wave of arbitrary intensity. It is shown that in general the six emanating waves: entropy wave, forward fast magnitosonic wave, forward and backward slow magnitosonic waves and Alfven waves appear behind the discontinuity. In addition, the shock surface can be disturbed by small oscillations. The correct formula describing the oscillations has been obtained. Amplitudes and propagation angles of all emanated waves have been calculated in dependence on orientation of wavevector of the incident perturbation and orientation and intensity of the ambient magnetic field. It is shown that if the incident angle is large, the refracted wave transfers into the elliptical polarized surface wave. We conclude that interaction of incident wave with discontinuity can effectively transform the oscillations of one type into other modes, and can lead to significant increase of the magnetic field and plasma pressure fluctuations. Comparison of the transmission calculations made in HD and MHD approximations is discussed.

D.N. Korolkov, M.B. Krainev (Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Prospect, 53, Moscow, 117924, Russia, krainev@fiand.msk.su)

It is usually assumed that the influence of the magnetospheric magnetic fields (MMF) on the primary cosmic ray (CR) intensity inside magnetosphere could be described by the integral characteristics of MMF-CR interaction - cutoff rigidity and angles of assymptotic direction - which can be calculated using the adequate MMF model. From this viewpoint the characteristics of the local MMF near the site of CR measurement is important only insofar as they influence the integral characteristics. On the other hand in the experiments, where the secondary CR of small energies from large solid angles are detected, the dependence of the detector count rate both on some complex integral MMF parameter and on the local MMF strength could be expected. Here we consider our long-term (since 1957) experiment on the frequent stratospheric sounding of cosmic rays. The aim of this talk is two-fold: 1) to formalize the connections between the primary CR beyond magnetosphere and the count rates of FSS detectors in order to isolate the relevant integral MMF-CR parameter and 2) to bring forward arguments for the manifestation of the local MMF variations in the high-latitude FSS data.

V.S. Makhmutov, G.A. Bazilevskaya, M.B. Krainev, A.A. Lazar (Lebedev Physical Institute,Russian Academy of Sciences, Leninsky Prospect, 53, Moscow, 117924, Russia, makhmutv@fiand.msk.su)

The energetic electron precipitation events (EPEs) in the Earth's polar atmosphere (Murmansk region, 68.95 N, 33.05 E and Mirny, Antarctica-66.57 S, 33.05 E) were observed in the long-term balloon cosmic ray experiment beginning from 1958 up to now. The EPEs occurrence demonstrates rather regular patterns on the 11-year and 1-year basis. The spectra of precipitating electrons derived from the stratospheric measurements can be described as exponential function dN/dE = No*exp(-E/Eo), where No=10² - 10⁵ (1/cm²*s*sr) and Eo in the range 10 - 300 keV. We will concentrate on the EPEs observed in 1994, when strong enhancements of energetic electrons were also observed at the geostationary orbit (GOES-7). The results obtained in the stratosphere are compared with the available data from GOES-7, geomagnetic data, etc., in order to find relation between the features of EPEs and geomagnetic, interplanetary conditions.

Stochastic resonance in runaway electron kinetics and some peculiarities of high atmospheric lightning

A.E. Dubinov, K.E. Mikheyev, V.D. Selemir, A.V. Sudovtsov

It is well known that the electrons moving through the gas in external electric field in some conditions can form two stable energetic groups of electrons: the group of non-relativistic electrons with energy 1-10 keV and the group of so-called runaway electrons with energies higher than 1 MeV [1,2]. The appearance of such bistable system is a result of non-monotonic dependence of the electron dynamic friction force (which depends on the elastic and non-elastic transactions as well as radioactive losses).

As a result of numerical Fourier transforms of the Langeven equation calculations, which describes the dynamic of the electrons flow including the group of runaway electrons, was obtained that during the electrons motion, the process of stochastic self-excitation of oscillating transfers of electrons from one group to another takes place. The appearance of these oscillations is an example of such well-known dynamic phenomenon as stochastic resonance [3] in non-potential systems.

The discovered peculiarity in the kinetics of electrons can add some new particular consequences to the theory of the initiations of high atmospheric lightning, based on the important role of runaway electrons [4]. For that purpose, the dependence of the frequency of self-excitation from the height was calculated. Thus, for example, at the height of 40 km in the external electric field with the strength of 10 kV/cm the frequency of self-excitation was about 0.5 kHz.

[1] Dreiser H., // The second international conference for peaceful using on nuclear energy, Geneva, 1958, p.170

[2] Babich L.P. // Teplofizika Vysokih Temperatur, 1995, V.33, p. 659

[3] McNamara B., Wiesenfeld K., // Phys. Rev. A, 1989, V.39, p.4854

[4] Roussel-Dupre R., Gurevich A.V., // Phys. Rew. E, 1994, V.49, p. 2257

L. Borovkov, L. Lazutin (Polar geophysical Institute, Apatity, Russia)

J.P. Treilhou (CESR, University of Paul Sabatier, Toulouse, France)

K.R. Lorentzen, M.P. McCarthy (University of Washington, Seattle, USA)