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561.
562.
Within the framework of the Space Weather program, 25-year data sets for solar X-ray observations, measurements of plasma and magnetic field parameters in the solar wind, and D
st index variations are analyzed to reveal the factors that have had the greatest influence on the development of magnetospheric storms. The correlation between solar flares and magnetic storms practically does not exceed a level of correlation for random processes. In particular, no relation was found between the importance of solar flares and the minimum of the D
st index for storms that could be connected with considered flares by their time delay. The coronal mass ejections (CME; data on these phenomena cover a small part of the interval) result in storms with D
st < –60 nT only in half of the cases. The most geoeffective interplanetary phenomena are the magnetic clouds (MC), which many believe to be interplanetary manifestations of CMEs, and compressions in the region of interaction of slow and fast streams in the solar wind (the so-called Corotating Interaction Region, CIR). They correspond to about two-thirds of all observed magnetic storms. For storms with –100 < D
st < –60 nT, the frequencies of storms from MC and CIR being approximately equal. For strong storms with D
st < – 100 nT, the fraction of storms from MC is considerably higher. The problems of reliable prediction of geomagnetic disturbances from observations of the Sun and conditions in interplanetary space are discussed. 相似文献
563.
M B Simakov E A Kuzicheva I L Malko 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,19(7):1059-1062
The abiogenic synthesis of pyrimidine nucleotides in solid state has been investigated. Our experiment indicates that natural nucleotides are produced in thin films prepared from nucleoside and inorganic phosphate by irradiating with vacuum ultraviolet light (VUV, lambda=100-200 nm). We have investigated the influence of the type of nucleic acids base (thymidine, cytosine, uracil) and the structure of sugar moiety (ribose or deoxyribose) on the course and yield of reaction. We compared the action of vacuum ultraviolet light with action of gamma-radiation, heat and biology significant UV (254 nm) which have been investigated earlier. The occurrence of these reaction in open space is discussed. 相似文献
564.
C. S. Zerefos D. S. Balis P. Zanis C. Meleti A. F. Bais K. Tourpali D. Melas I. Ziomas E. Galani K. Kourtidis A. Papayannis Z. Gogosheva 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(12):1955-1963
Intensive measurements of UV solar irradiance, total ozone and surface ozone were carried out during the solar eclipse of 11 August 1999 at Thessaloniki, Greece and Stara Zagora, Bulgaria, located very close to the footprint of the moon's shadow during the solar eclipse with the maximum coverage of the solar disk reaching about 90% and 96% respectively. It is shown that during the eclipse the diffuse component is reduced less compared to the decline of the direct solar irradiance at the shorter wavelengths. A 20-minute oscillation of erythemal UV-B solar irradiance was observed before and after the time of the eclipse maximum under clear skies, indicating a possible 20-minute fluctuation in total ozone presumably caused by the eclipse induced gravity waves. The surface ozone measurements at Thessaloniki display a decrease of around 10–15 ppbv during the solar eclipse. Similarly, ozone profile measurements with a lidar system indicate a decrease of ozone up to 2 km during the solar eclipse. The eclipse offered the opportunity to test our understanding of tropospheric ozone chemistry. The use of a chemical box model suggested that photochemistry can account for a significant portion of the observed surface ozone decrease. 相似文献
565.
R Facius K Scherer G Reitz H Bucker L V Nevzgodina E N Maximova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):93-103
The potentially specific importance of the heavy ions of the galactic cosmic radiation for radiation protection in manned spaceflight continues to stimulate in situ, i.e., spaceflight experiments to investigate their radiobiological properties. Chromosome aberrations as an expression of a direct assault on the genome are of particular interest in view of cancerogenesis being the primary radiation risk for man in space. In such investigations the establishment of the geometrical correlation between heavy ions' trajectories and the location of radiation sensitive biological substructures is an essential task. The overall qualitative and quantitative precision achieved for the identification of particle trajectories in the order of approximately 10 micrometers as well as the contributing sources of uncertainties are discussed. We describe how this was achieved for seeds of Lactuca sativa as biological test organisms, whose location and orientation had to be derived from contact photographies displaying their outlines and those of the holder plates only. The incidence of chromosome aberrations in cells exposed during the COSMOS 1887 (Biosatellite 8) and the COSMOS 2044 (Biosatellite 9) mission was determined for seeds hit by cosmic heavy ions. In those seeds the incidence of both single and multiple chromosome aberrations was enhanced. The results of the Biosatellite 9 experiment, however, are confounded by spaceflight effects unrelated to the passage of heavy ions. 相似文献
566.
A. I. Efimov 《Space Science Reviews》1994,70(1-2):397-402
Velocity measurements of the solar wind in the region of its acceleration were carried out in 1984 with Venera Orbiters using the following specific radio sounding techniques: (i) phase and frequency correlations from two or three widely-spaced ground stations; (ii) phase and frequency correlations from two spacecraft and two widely-spaced ground stations; (iii) two station two-way coherent Doppler measurements; (iv) determination of the break frequency in power spectra of intensity fluctuations. Our results are substantially lower than those derived from direct Doppler shift measurements of transition region and lower coronal resonance lines and those from measurements applying the Doppler dimming technique. 相似文献
567.
K Kobayashi H Masuda K I Ushio A Ohashi H Yamanashi T Kaneko J I Takahashi T Hosokawa H Hashimoto T Saito 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(2):207-215
Various types of organic compounds have been detected in Jupiter, Titan, and cometary coma. It is probable that organic compounds were formed in primitive Earth and Mars atmospheres. Cosmic rays and solar UV are believed to be two major energy sources for organic formation in space. We examined energetics of organic formation in simulated planetary atmospheres. Gas mixtures including a C-source (carbon monoxide or methane) and a N-source (nitrogen or ammonia) was irradiated with the followings: High energy protons or electrons from accelerators, gamma-rays from 60Co, UV light from a deuterium lamp, and soft X-rays or UV light from an electron synchrotron. Amino acids were detected in the products of particles, gamma-rays and soft X-rays irradiation from each gas mixture examined. UV light gave, however, no amino acid precursors in the gas mixture of carbon monoxide, nitrogen and nitrogen. It gave only a trace of them in the gas mixture of carbon monoxide, ammonia and water or that of methane, nitrogen and water. Yield of amino acid precursors by photons greatly depended on their wavelength. These results suggest that nitrogen-containing organic compounds like amino acid precursors were formed chiefly with high energy particles, not UV photons, in Titan or primitive Earth/Mars atmospheres where ammonia is not available as a predominant N-source. 相似文献
568.
A.I. Podgorny I.M. Podgorny 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,19(12):1929-1932
The patterns of reconnection in the Earth magnetotail and in the solar corona above the active region are presented. The electric field and field-aligned currents (FAC) generation in the current sheet are discussed. 相似文献
569.
I.V. Chashei 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,20(12):2299-2302
Small scale turbulence in the solar corona and the solar wind is considered. The estimates of dissipation scale in the inner heliosphere are obtained in the assumption that the initial source of turbulence is located near the chromosphere-corona transition layer. Theoretical results are compared with radiooccultation data. 相似文献
570.
S I Ramirez R Navarro-Gonzalez P Coll F Raulin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(2):261-270
A quantitative comparison of the products arising from the irradiation of a Titan's simulated atmosphere is presented. The energy sources used represent some of the main events that occur in the satellite's atmosphere. All of the compounds identified are classified in the hydrocarbon and nitrile chemical families. Almost all of the detected compounds in Titan's atmosphere are produced by one or more energy sources. The compounds with the highest energy yields include the C2 hydrocarbons, methanonitrile and ethanonitrile. The possibility of using some of the produced organics as tracer compounds during the Huygens descend to identify the leading energy form in the different atmospheric levels remains open. 相似文献