Russia, 142092, Troitsk, Moscow Region

Tel.: 7(095)334 01 20 Fax: 7(095)334 01 24

e-mail: root@izmiran.rssi.ru ,

home-page: www.izmiran.rssi.ru

The Institute of Terrestrial Magnetism, Ionosphere and Radio Wave propagation deals with solar and terrestrial physics, physics of the solar-terrestrial relations, cosmic rays, physics of the ionosphere and magnetosphere, the ionosphere and magnetosphere radio wave propagation, the magnetism of the Earth, the planets and bodies of the solar system. All studies undertaken at the Institute deal mainly with electrodynamic processes in continuous phases listed above. These processes are acompanied by optical, nuclear and other phenomena reflecting the specifics of objects studied. A distinctive feature of IZMIRAN research is a desire to stage multi-disciplined investigations, using ground, aircraft, balloon, rocket and satellite methods. The most noticeable results have been obtained in programmes based on cooperation and coordination of efforts of Soviet/Russian and foreign scientists and specialists in related disciplines.

The Institute met its 59th anniversary in January 1999. At present the Institute employs about 750 staff, of whom the R@D employees are about 300. The bulk of the Institute is located in the town of Troitsk, outside Moscow, which is one of scientific centres of the Russian Academy of Sciences. In addition, IZMIRAN comprises the St.Petersburg branch and magnetic ionospheric observatory in Kaliningrad.

The history of IZMIRAN is largely that of investigating magnetic storms and sub-storms on the Earth surface, in circum-terrestrial and interplanetary space, initially by means of a network of ground stations of the Soviet Union (1930s -- 1940s) and the nonmagnetic skunner "Zarja", then through the extensive use of magnetic measurements on artificial Earth satellites and on automatic stations.

With the advent of the space era investigators became able to make direct measurements in outer space (near-Earth space in particular) by means of rockets, satellites, orbital stations and spacecrafts. IZMIRAN was one of the trail-blazers here

In 1958, IZMIRAN magnetologists for the first time made magnetic measurements from an artificial Earth satellite. World magnetic surveying from an artificial Earth satellite began in 1964, from the satellite Cosmos-49, equipped with proton magnetometer. Global survey of the field modulus from the near-polar orbit was effected in 1970 from the satellite Cosmos-321, equipped with a quantum cesium magnetometer. In particular, this survey made it possible to explore polar electro-jets, the effect of longitudinal magnetospheric-ionospheric currents, and the effect of an non-ionospheric ring current. The effect of an ionospheric equatorial electro-jet over the ionosphere and its induction effect in the Earth were measured for the first time.

IZMIRAN has taken an active part in developing and performing the active experiments involving injection of particles into outer space. The Institute coordinated a number of Russian and international rocket experiments and developed a large-scale international satellite experiment called APEX (Active Plasma Experiment, launch -- 1991, active period -- upto 1997). Its main scientific objectives were to simulate an artificial aurora and to study optical and radio emission from the aurora region, the study of the dynamics and relaxation of modulated electron and plasma jets, artificially injected in the circum-terrestrial plasma.

Already on the first Soviet satellites IZMIRAN began investigating electromagnetic emissions and signals from circum-terrestrial plasma. An important result obtained by means of the satellite Intercosmos-19, was the discovery of an anomalous increase in the intensity of low-frequency emissions (0.1-20kHz) over the epicentrial regions of future earthquakes.

IZMIRAN studies phenomena of solar-terrestrial physics starting from the onboard investigation of the solar ultraviolet and gamma-ray emission (satellites Cosmos-166,230, spacecrafts of Intercosmos series, Phobos space probes, Prognoz, Soyuz, et cetera).

A long series of experimental and theoretical investigations was carried out on solar radio outbursts and their fine structure in the metre wavelength. These helped to assess parameters of solar corona.

Multi-disciplined experimental and threoretical investigations produced a two-component model of the sunspot, which for the first time gave a consistent explanation for all kinds of emissions from the sunspot area, also explaining the structure and the dynamics of the sunspot.

• Experimental and theoretical investigation of the problem of the geomagnetic field generation was carried out. The spectral space-temporal analysis of the field behaviour during the last century is performed, and it is shown that its spectrum corresponds to that of a random distribution. This result confirms the statement about the stohastic nature of the geomagnetic secular variations of the spectral range and allows to make a choice in favour of the short-correlated dynamo mechanism as the very mechanism responsible for the Earth magnetic field generation. It appears that a problem of the magnetic force line reconnection is the one of the most important in such kind of dynamo. A new generalization of the known topological invariants is found, which constrain from below a possible value of electromagnetic energy in the electroconductive liquid medium.

• The main scientific results of the International Project APEX (1991 -- 1997).

1. Within the frame of the space experiment it was shown for the first time that there is an opportunity of ballistic transformation of a wave propagating through an ionospheric wave barrier. A qualitative theory of this phenomenon is formulated.
2. New nonlinear electromagnetic structures resembling collisionless shock waves ("jumps" of electric and magnetic fields, plasma density "jumps") are revealed.
3. It is shown that in polar area there exists a new type of ionospheric throws -- the so-called "slanting" ionospheric throw.
4. The modulated electron beam is shown to be of use for the nonlocal determination of electron density and the magnetic field amplitude.

• Recently proposed a new effective ionospheric index MF2 and a multiquadric (MQ) method for spacial approximation were used to derive a new monthly median model MQMF2 of foF2 (F2 -layer critical frequency) and M(3000)F2 (an oblique incidence propagation parameter) over Europe. The results of international testing in the framework of COST 251 European Project has shown the MQMF2 model to be the best. It was officially accepted as a result of COST 251 Project and recommended for the international use.

• The cooling of thermal electrons in the ionosphere is revised on the base of the theoretical computations of cross sections for electron impact excitation of the ground-state fine-structure levels in atomic oxygen. It is found that the electron temperature variations are determined by Coulomb collisions of electrons with oxygen ions and excitation of the vibrational states of N₂ at F region altitudes, but not by the atomic oxygen fine structure excitation as it was assumed in previous studies. The result obtained changes the generally accepted conception about the processes of electron temperature altitude profiles formation within the ionosphere.

• The problem of the ionospheric electric field generation due to field-aligned currents was examined with the explanation of the mesoscale convection vortex at dayside of high lattitude ionosphere detected by SuperDARN radar network. The simultaneous Viking and DMSP satellites data show close relation of the magnetosphere convection to plasma domains. The antisunward convection is typical for the inner magnetosphere and the plasma sheet. A quantitative comparison of the high-lattitude convection patterns under space weather IZMEM model and SuperDARN radars observations showed that IZMEM model describes correctly the large-scale distribution of the convection velocity in the high lattitude dayside sector.

• The energy stored in geotail was studied for magnetic storm on November 23-27 1986 using the dynamic paraboloid model and data of on-ground and satellite measurements. It is shown that the amount of energy correlates strongly with power delivered from solar wind to magnetosphere.

• IZMIRAN is the Head Institution charged with preparation and implementation of CORONAS-I and CORONAS-F missions. CORONAS as a whole is a unique complex space mission, comprising three special-purpose satellites to be launched in 1994, 1999, and after 2000. The first satellite of the series, CORONAS-I was launched in 1994. The chosen polar orbit (altitude about 500km above the Earth, inclination about 83 degrees) ensures continuous observations of the Sun in recurrent intervals about 20 days. The scientific payload of CORONAS is designed to measure electromagnetic radiation in a broad range from radio to gamma wavelengths, as well as the fluxes of neutral (neutrons) and charged (electrons, protons and nuclei) solar particles. A detailed information on data and results of separate measurements can be found at IZMIRAN Web-site. Here it is worth to mention the data obtained by the DIFOS photometer.

This photometer provided a continuous series of observations of solar brightness in three spectral ranges with a general duration of 52 days. The power spectra of global oscillations of the Sun were plotted to reveal the p-modes of the order l = 0,1,2. The frequency splitting of p-modes as a result of solar rotation was demonstrated experimentally.

• The model of coronal mass ejection was developed, basing on the break of equilibrium of the twisted magnetic tubes(loops), emerging from the photosphere to the corona. It is shown that the loops, that loose a large amount of mass owing to their slow emergence or rapid mass outflow, are not susceptible to eruptive instability. The rapidly emerging loops, that therefore cannot loose much mass, experience eruptive instability, that leads to a mass ejection. The onset of the kink instability which may occur at the stage of non-quasistatic expansion of the tube results in an explosive release of magnetic energy.

• An up-to-date concept of solar activity, based on the entire complex of phenomena and structures in the local and global magnetic fields in the Sun, was developed using ground-based data from Russian observatories, Stanford (USA), Kodaikanal (India), Nobeyama (Japan), as well as satellite observations on KORONAS (Russia), Yohkoh (Japan), SOHO (ESA), and TRACE (USA). According to this concept:

1. Solar activity manifests itself in various forms at all latitudes from the poles to the equator and at all space scales from several hundred to many hundred thousand km. Some structures and phenomena may cover nearly the entire solar disk and are called global.
2. The active events are not confined to the relatively short periods of the 11-year maxima, but occur permanently in one or other form, including the minimum epochs of the 11-year cycles.
3. A certain parallelism exists between the local and large-scale (global) fields, so that most objects and phenomena in local fields have their analogy in global fields (e.g. sunspots -- coronal holes, flares -- coronal mass ejections, active region filaments – giant global filaments).
4. Giant and super-giant systems are shown to exist in the large-scale solar magnetic fields, the former determining the occurrence rate and energy and the latter – the location of coronal mass ejections.
5. Intensive kG fields are revealed in the polar zone. It is shown that processes in the local fields follow processes in the global fields with a delay of 5-6 years.
6. A new phenomenon of the large-scale solar activity has been discovered – long bright chains with characteristic dimensions comparable with the diameter of the solar disk. It is found out that often, the light elements and bright points are not randomly scattered over the solar disk, but are rather arranged in large-scale chains and threads of various configurations along certain structures.

These results make it possible in prospect to conceive a physically consistent model of solar activity, including its forecast. (The results were obtained at IZMIRAN in collaboration with GAO RAN)

• For the first time the atlas of magnetic maps of the Baltic Sea is prepared and published. It contains detailed information about space-temporal distribution of the geomagnetic field components, its secular variations, and information about geological structure of the bottom of the Baltic Sea. All data are presented both in analogous and digital version in the scale 1 : 5 000 000 ( St.Petersburg Branch of IZMIRAN in collaboration with the Institute of Geodesy and Cartography of Republic Poland).

• A new method of joint analysis of data from magnetic observatories and satellite surveys has been developed. It is the space-time modeling of geomagnetic variations with their division into natural orthogonal components which correspond to different geophysical sources of the variations. The method can be applied to the regional or global analyses of variations in different spectral ranges.

• Satellite magnetic surveys data were analyzed to extract magnetic anomalies of the crustal origin. Developed for this aim new methods allow to design global and regional maps and models of magnetic anomalies. Thus obtained anomalies correlate with those, obtained from stratospheric balloons observations of the vertical component of the magnetic field total force, as vell as with the main units of the Earth' crust tectonic structure.