SOLAR GEOPHYSICS: UPS AND DOWNS

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Источник: Science in Russia, №5, 2012, C.92-96

There was a time when we in this country had an effective network of ground-based research facilities like telescopes, radars, lidars and so forth for making a study of the sun and circumterrestrial space. The results thus obtained were on a par with the world level. Yet as of the early 1980s the situation was starting to change--not for the better either. With the breakup of the Soviet Union a decade after part of the equipment passed into the possession of the former constituent Soviet republics, while the rest became outdated for lack of funds for modernization. Meanwhile it is highly important to look into the ongoing solar processes and their effects on interplanetary space, the magneto- and ionosphere, and the upper atmosphere, that is what concerns solar geophysics.

 

As to the circumterrestrial space, it is no more an exotic thing being now part and parcel of human activities. This idea was voiced by Hely Zherebtsov, a foremost interplanetary researcher expert in space weather, and full member of the national Academy of Sciences. Interviewed by Galina Kiseleva of the newspaper Nauka v Sibiri ("Science in Siberia"), he continued:

 

-- Working in near-earth space today are a great number of orbiters and other vehicles playing a big role in our vital activities. Radio and telecommunications, Internet and other facilities are a part of this global network. Add also the International Space Station making an active use of theoretical knowledge for practical problem solving in the interests of the nation's economy and security. The station is carrying out a variety of research projects, too. Therefore, Dr. Zherebtsov says, it is important to be in the know about processes in and on the sun, in circumterrestrial space, in the magneto-sphere and ionosphere. To cull related data we need not only orbital satellites, we need also ground-based facilities, such as solar optical and radio telescopes, radars and lidars (laser infrared radars).

 

As Dr. Zherebtsov sees it (for twenty-six years, from 1984 to 2010, he had been heading the Irkutsk-based Institute of Solar Geophysics affiliated with the Siberian

 
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Branch of the Academy of Sciences), related problems should be handled within the framework of a megaproject, the National Geophysical Complex of the RAS. Since 2007 the Irkutsk research institute has been cooperating with the RAS, as this program was tabled to the federal government on the instructions of President Putin. It provides for a network of major experimental setups based on observatories run by the Irkutsk Institute. This network will be geared to basic and practical problem solving in the interests of national security and development of new competitive space technologies, including dual-purpose facilities. The total bill of federal investments runs into ten billion rubles. When commissioned, this complex will enable our country to shift to a new and higher level of experimental research in solar geophysics. The megaproject won support from federal ministries and agencies having a stake in its success. Yet its financing from the federal budget was shelved, though the Siberian Branch of the Russian Academy of Sciences had earmarked funds for research and R&D works.

 

It was quite natural for the Institute of Solar Geophysics to come up with the initiative of the megaproject. The Irkutsk research center is Russia's largest involved with studies of the sun and interplanetary space, and their effects on the earth. It has no equal in the set of instruments, testing ranges and observatories all over the vast expanses of eastern Siberia.

 

We might as well recall here it was in Irkutsk that a magnetic observatory was opened in 1886 for systematic geo- and heliophysical inquisitions. In 1908 this observatory registered the sudden dramatic change of the earth's magnetic field in the wake of the fall of the Tunguska space body* In 1956, just on the eve of the International Geophysical Year, the Irkutsk observatory was reorganized into an amalgamated magneto-ionospheric station. Two years later, the first instruments appeared there for observing the sun over the optical and radio bands. In 1960 the station changed its status to become the Siberian

 

See: E. Galimov, M. Nazarov, "Centennial of the Tunguska Event", Science in Russia, No. 3, 2008.--Ed.

 
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Institute of Terrestrial Magnetism and Ionosphere; today it is the Institute of Solar Geophysics of the Siberian Branch of the Russian Academy of Sciences.

 

Eastern Siberia boasts of an excellent astrophysical climate. So, in 1960 ground was broken for a Sayan Mountains solar observatory, 300 km west of Irkutsk, 2,000 meters above sea level, on the Soviet-Mongolian border. An astrophysical observatory was founded 60 km southwest of Irkutsk on a mountain slope above Lake Baikal; it was equipped with a large solar vacuum telescope. Yet another one, a radioastronomical observatory, rose in a scenic valley next to Lake Baikal. Quite nearby, near the Badary woodland, a unique Siberian Solar Radio Telescope was built. Its radio interferometer is composed of 256 antennae arranged in the shape of a giant cross. In 1996 its makers merited a federal government prize.

 

The Irkutsk Institute survived with a minimum of losses in the hard 1990s. Thanks to effective managerial policies it upgraded the observatories and testing-ranges, and installed new equipment there. The 50-year record of this research center shows that its collective is able to shoulder a program on the national scale.

 

Our megaproject, Hely Zherebtsov went on to say, will integrate the large solar telescope, radio heliograph and the multifunctional radiophysical complex for further studies of circumterrestrial space. Hooked in will be the system of radars and the lidar-optical complex for studying the upper layers of the atmosphere.

 

A coronograph telescope with a 3 m mirror, when commissioned, is bound to make a decisive contribution to our understanding of solar activity orchestrating weather processes in interplanetary and near-earth space. "We know that powerful solar flares generate flows of high-energy particles. Solar corona mass discharges beget Shockwaves that speed them up. All that can interfere with the performance of technical systems and endanger the health of astronauts and airline passengers in the polar zones."

 

The trigger mechanism of imbalance is anchored in the fine structure of the solar magnetic field. The coronograph telescope will furnish exact data on the structure of magnetic fields deep in the photosphere, and will make it possible to pry into subphotospheric strata. "Ultimately, we shall come to a physically validated idea of a solar-terrestrial interaction model," Dr. Zherebtsov stressed.

 

Another device--a multiwave radio heliograph or a multiwave solar radio telescope hooked to the helio-geophysical complex--will help astrophysicists in studying processes in the solar corona. Solar flares as well as corona mass discharges result in a dramatic increase in solar wind plasma currents, in flows of fast hard electromagnetic radiation in circumterrestrial space. The magnetic field of the solar atmosphere is the energy source of explosive processes. The earth-bound plasma discharges draw in magnetic clouds whose fields are exerting a drastic effect on the geoefficiency of solar wind disturbances. Determining the structure of such fields is a key issue in our understanding of the nature of solar activity and for methods of space weather forecasts. Coronal magnetic fields can be measured only by emissions from the sun, the star nearest to us, should such measurements be made over the radio bands. Observations on a modern radio heliograph will likewise allow to glean qualitatively new information relevant to solar activity.

 

Our megaproject envisages three T-shaped antenna arrays (beam length, ~1 km) to be built stage by stage. Signals from the arrays will be harvested in the control central with the aid of opticalfiber communication lines, with as many as six solar images obtained at different frequencies. The project will take in the radiator of the Siberian Solar Radio Telescope at Badary and its infrastructure.

 
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Two telescopes will be set up ~2,000 m above sea level for a monitoring of powerful proton flares. One will be installed on the grounds of the Sayan Mountains solar observatory, and the other, in the community of Nizhni Arkhyz (Karachayevo-Cherkesskaya Republic, Caucasus), the site of RATAN-600, a megaradio telescope of the Russian Academy of Sciences. This system should work as one instrument, its components spaced wide apart.

 

A radiophysical complex for studying the air layers closest to the terrestrial surface will involve great expenditures. The upper atmosphere, at altitude from 80 to 1,500 km, is an essential part of the sunearth system playing a key role in processes implicated in the interaction of ionized and neutral gas envelopes. This is the region acted upon by processes on the sun, on the ground and ocean surface, and below. The radiophysical complex is bound to bring us closer to the understanding of these processes.

 

An important role is assigned to a mesosphere/strato-sphere/troposphere radar that will make it possible to measure atmospheric parameters at 1 to 90 km altitude. This method, the world's first, will allow to approach the atmosphere and its layers as one system. An up-to-date incoherent scattering radar, a component part of the radiophysical complex, will furnish data on near-earth space starting from the ionosphere (100 km above the ground surface) to the magnetosphere (2,000 km) inclusive.

 

The processes we are studying, Dr. Zherebtsov said, are global, planetary, and it is impossible to obtain an integral picture of this or that phenomenon if observations are made just at one place. Therefore, such large-scale studies should be international. The study of the ionosphere and upper atmosphere has practical applications in different fields of science and engineering, specifically, in space and ground radio communications, radar, ship and aircraft navigation, and space flights.

 

The radiophysical complex will be based 200 km from Irkutsk, and it fill in the present gap in the longitudinal chain of geophysical centers of the United States, Europe and Japan. This region is known for high seismicity that provides required conditions for atmosphere and ionosphere explorations. In the last few years this area has seen many unusually powerful disturbances in the upper atmosphere, also during moderate magnetic storms. Measurement data will be of much significance for learning about the global distribution of ionosphere/ atmosphere parameters, an essential thing for understanding sundry planetary phenomena.

 

The action of the solar wind on the terrestrial magneto- and ionosphere is one of the central problems of solar geophysics now in the sphere of attention of the international "Superdarn" network comprising 17 high-frequency shortwave radars of coherent backward scattering, their field covering the polar regions of the

 
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Northern and Southern Hemispheres. This network is run by nine countries: USA, Canada, Great Britain, France, Italy, Japan, South Africa and China. Plans are underway to set up yet another seven radars in polar and subpolar regions. Yet this cooperative undertaking is hardly feasible without Russia, for her territory covers a significant longitudinal sector. So, it will be impossible to monitor the system of ionospheric plasma convection in the Northern Hemisphere and forecast upper atmosphere disturbances and perturbations during magnetic storms. Therefore our national program provides for an addition to the Russian network of coherent high-frequency radars to supplement the "Superdarn" network. Thus it will be able to realize its potential to the full, and our research scientists will get a chance of parity participation in the international cooperative effort.

 

We should built at least four radar stations: at testing ranges of the Space Physics Research Institute (at Paratunka, Kamchatka) in the Far East, at Magadan and at Bratsk in eastern Siberia, and near Yekaterinburg in the Urals so as to close the ring of monitoring stations targeted into the polar and subpolar ionosphere of the Northern Hemisphere.

 

And last but not least, a lidar optical complex should become a significant addition to the national heliogeo-physical program. Optical devices like interferometers, photometers, spectrographs and lidars are in for scanning the upper atmosphere and ionosphere composed of neutral gas and charged glowing particles (electrons and ions). Lidars (laser infrared radars) send short light pulses into the atmosphere; bounced off, such signals supply data on gas envelope parameters.

 

Our program provides for a multichannel lidar on the grounds on the Baikal Astrophysical Observatory at Listvyanka for collecting important data in the medium and upper layers of the atmosphere: on temperature, wind density and aftereffects of natural and anthropogenic man-induced processes.

 

This lidar-optical complex is also to probe into what we call the mesopause, that is in the 80-100 km range above the ground surface. "The scientific community is intrigued: if the climate changes as high as the meso-sphere? If it does, then why?" The multichannel lidar will elucidate these and other moot points.

 

Unfortunately our country does not have at its disposal a far-flung set of technical facilities, and this extends her lag. Over the last twenty years the West has created a great number of major experimental setups and observatories of a new generation. For instance, a brand new heated stand and radar has been commissioned in Alaska to do ionospheric sounding by powerful shortwave radio frequency emission. The United States has built an incoherent scattering radar in that country's north. Effective facilities are now in Spitsbergen, too. China has deployed a ramified network of regional stations. European countries as well as the United States are building super solar telescopes. The RAS National Heliogeographical Complex is in the mainstream of such trends. If realized, our megaproject will make it possible to bridge our lag and reach the forward frontiers of solar geophysics.

 

G. Kiseleva"Megaproject, a Breakthrough to World Level Knowledge", Nauka v Sibiri ("Science in Siberia") newspaper No. 15, 2012


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() Источник: Science in Russia, №5, 2012, C.92-96

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