International Geophysical Year IGY

International Geophysical Year (IGY)

 

the 18-month period from July 1, 1957, through Dec. 31, 1958, during which 67 countries conducted geophysical observations and research according to a common program and methodology. The IGY was a successor to the two International Polar years. A special committee was established to direct and coordinate the program. The IGY was extended into 1959 and was called International Geophysical Cooperation.

The IGY program, which coincided with a period of maximum solar activity, included observations in various fields, among them aerology and meteorology (including observations of solar radiation, atmospheric ozone, and noctilucent clouds), oceanography, glaciology, magnetism, gravimetry, and seismology. The upper atmosphere was studied—the aurora, the ionosphere, meteors, and cosmic rays. The findings constituted a major contribution to the study of solar-terrestrial relations. Of particular importance was the investigation of Antarctica, where various countries established stations for observations (for example, the Soviet Union’s Mirnyi Observatory) and where a number of expeditions were sent into the interior. Numerous hydro-graphic profiles were secured in all the oceans, in particular by the Soviet ships F/Ywz’and Ob’ The USSR and the United States established several drifting ice-pack stations in the Arctic Ocean.

During the IGY, new equipment and new methods of investigation were used (for example, many geophysical rockets and artificial earth satellites were launched), which resulted in the first estimates of the density and temperature of the atmosphere above 200 km. The earth’s radiation belts were discovered, and it was possible to determine the density of meteoric matter in interplanetary space, an important factor for ensuring safety during space flights.

On the basis of the data from IGY observations in Antarctica, the southern Cold Pole, with mean annual temperatures of as low as — 57°C, was discovered and the average positions of the six regions near the shores of Antarctica where cyclones form with greatest frequency were determined. Visual and radar observations of the luminous traces of meteors made it possible to determine the velocity and direction of winds at altitudes up to 110 km and discover the existence of the semidiurnal flow there. It was proved that the ozone layer is thin and situated high in the tropic zone, and thick and situated low in the polar zone. Rather fast currents were detected at great depths in the ocean. New glacial regions were discovered in Eastern Siberia. It was proved that the thick ice of Antarctica, whose total volume is about 24 X 106 km3, has “pressed down” the formerly mountainous continent to sea level and even below. Seismic observations showed that the extended volcanic zones along the edges of the continents are related to the transition from the thin oceanic crust of the earth to the thick continental crust. The presence of helium in the earth’s upper atmosphere and the existence of streams of protons, which burst into the atmosphere from space and apparently are of solar origin, were proved on the basis of the aurora’s spectrum.

In the ionosphere, ion clouds with heightened density of ionization, which as research showed is related to the waves in the ionosphere, were discovered and described in detail.

The first scientific results of the IGY were summarized in 1958 at the IGY general assembly in Moscow. Copies of all data from IGY observations are stored in the world data centers in Washington and Moscow and in a number of special centers, for example in Geneva and London. In the USSR the results of the IGY have been published in a series entitled Results of the IGY (now titled Results of Research on International Geophysical Projects).

REFERENCE

Silkin, B. I., V. A. Troitskaia, and N. V. Shebalin. Nasha neznakomaia planeta. Moscow, 1962.

A. KH. KHRGIAN

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