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1.
The Siberian Solar Radio Telescope: the current state of the instrument,observations, and data 总被引:2,自引:0,他引:2
Grechnev V.V. Lesovoi S.V. Smolkov G. Ya. Krissinel B.B. Zandanov V.G. Altyntsev A.T. Kardapolova N.N. Sergeev R.Y. Uralov A.M. Maksimov V.P. Lubyshev B.I. 《Solar physics》2003,216(1-2):239-272
The Siberian Solar Radio Telescope (SSRT) is one of the world's largest solar radio heliographs. It commenced operation in
1983, and since then has undergone several upgrades. The operating frequency of the SSRT is 5.7 GHz. Since 1992 the instrument
has had the capability to make one-dimensional scans with a high time resolution of 56 ms and an angular resolution of 15 arc sec.
Making one of these scans now takes 14 ms. In 1996 the capability was added to make full, two-dimensional images of the solar
disk. The SSRT is now capable of obtaining images with an angular resolution of 21 arc sec every 2 min. In this paper we describe
the main features and operation of the instrument, particularly emphasizing issues pertaining to the imaging process and factors
limiting data quality. Some of the data processing and analysis techniques are discussed. We present examples of full-disk
solar images of the quiet Sun, recorded near solar activity minimum, and images of specific structures: plages, coronal bright
points, filaments and prominences, and coronal holes. We also present some observations of dynamic phenomena, such as eruptive
prominences and solar flares, which illustrate the high-time-resolution observations that can be done with this instrument.
We compare SSRT observations at 5.7 GHz, including computed `light curves', both morphologically and quantatively, with observations
made in other spectral domains, such as 17 GHz radio images, Hα filtergrams and magnetograms, extreme-ultraviolet and X-ray
observations, and dynamic radio spectra. 相似文献
2.
Large-scale ancient landslides of the area of more than 5 km2 and volume exceeding 200 × 106 m3 are characteristic features of the valleys incised in the northern periphery of the Crimean Mountains (Ukraine). The largely
affected area is located in the outermost cuesta range of the Crimean Mountains which consists of rigid Sarmatian limestones
overlying weak Middle Miocene and Upper Palaeogene deposits. A giant landslide arose in the Alma water gap as a reflection
of several coincident preparatory factors such as suitable bedrock stratification, smectite-rich bedrock exposed to swelling
activity, presence of faults parallel to the valley trend, and river capture event which preceded the landslide event. The
occurrence of such ancient megaslides is particularly interesting in the area which is characterized by low precipitation
(<500 mm/year) and weak contemporary seismicity. It probably reflects a more dynamic environment in humid phases of the Holocene;
however, seismic triggering along the Mesozoic suture zone cannot be rejected. Compressional features such as gravitational
folds in the central and distal parts of the landslide, which probably correlate with the whole landslide genesis or its significant
reactivation, arose, according to the radiocarbon dating, during the Holocene climatic optimum in the Atlantic period. The
slope deformation has been relatively quiescent since that time, except minor historic reactivization which took place in
the frontal part of the landslide. We suppose that the studied landslide could be classified as a transitional type of slope
deformation with some signs of spreading and translational block slides. 相似文献
3.
4.
Veronika S. HEBER Roger C. WIENS Amy J. G. JUREWICZ Nadia VOGEL Daniel B. REISENFELD Heinrich BAUR Kevin D. McKEEGAN Rainer WIELER Donald S. BURNETT 《Meteoritics & planetary science》2011,46(4):493-512
Abstract– We report concentrations and isotopic compositions of He, Ne, and Ar measured with high spatial resolution along a radial traverse of a silicon carbide (SiC) quadrant of the Genesis mission concentrator target. The Ne isotopic composition maps instrumental fractionation as a function of radial position in the target: the maximum observed isotopic fractionation is approximately 33‰ per mass unit between the center and periphery. The Ne fluence is enhanced by a factor of 43 at the target center and decreases to 5.5 times at the periphery relative to the bulk solar wind fluence. Neon isotopic profiles measured along all four arms of the “gold cross” mount which held the quadrants in the concentrator target demonstrate that the concentrator target was symmetrically irradiated during operation as designed. We used implantation experiments of Ne into SiC and gold to quantify backscatter loss and isotopic fractionation and compared measurements with numerical simulations from the code “stopping and range of ions in matter.” The 20Ne fluence curve as a function of radial distance on the target may be used to construct concentration factors relative to bulk solar wind for accurate corrections for solar wind fluences of other light elements to be measured in the concentrator target. The Ne isotopic composition as a function of the radial distance in the SiC quadrant provides a correction for the instrumental mass‐dependent isotopic fractionation by the concentrator and can be used to correct measured solar wind oxygen and nitrogen isotopic compositions to obtain bulk solar wind isotopic compositions. 相似文献
5.
Large-scale, low-gradient ancient landslides estimated at 5.4–18.9 km2 in area and 0.2–1.2 km3 in volume have been studied in the northern hilly periphery of the Crimean Mountains (Ukraine). They originated on slopes along wide water gaps of rivers (Belbek, Kacha, Alma and Biyuk–Karasu) crossing the cuestas of the northern foothills. The slopes generally consist of slightly northward tilting Miocene (mainly Sarmatian) limestones overlying weak, clay-rich Lower Neogene–Palaeogene substratum with a significant content of smectite. Although the region is characterised by the least active contemporary morphodynamics within the Crimean Mountains, the landslides which were studied are of the same size or even larger than various types of landslides occupying active geomorphic domains of the highest mountain range in the southernmost part of the peninsula. The landslides are generally a spreading type, but the sliding mechanics were probably very complex, involving toppling, rotational slides, gravitational folding and translational block slides. All the landslides which were studied are located in the vicinity of regional faults and three of them have headscarps aligned along faults. A common feature is also a location close (within several km) to the Mesozoic suture zone which is the most important tectonic feature in the northern periphery of the Crimean Orogene. This suture was formerly classified as aseismic; however, evidence of strong, low-frequency palaeoearthquakes was collected during the last decade within both the Mesozoic suture and the low-lying northern part of the Crimean Peninsula. Radiocarbon dating of deposits associated with the landslides has revealed at least two phases of increased landslide-activity during the Late Glacial chronozone and Holocene epoch. The main landslide phase presumably took place at some time between the Late Glacial and Atlantic chronozones. Minor reactivation of landslide toes occurred during the Subatlantic chronozone and some of them have been active up to recent times. The first major landslide phase was possibly triggered by an earthquake, whereas late Holocene activity can be attributed both to seismic and hydroclimatic factors. 相似文献
6.
Gabriella Sátori Michael Rycroft Pál Bencze Ferenc Märcz József Bór Veronika Barta Tamás Nagy Károly Kovács 《Surveys in Geophysics》2013,34(3):255-292
This paper gives a resume of the papers written in English which (a) describe some of the recording instruments in use at the Nagycenk Observatory (NCK) since the International Geophysical Year (IGY 1957–1958) and up to the present time, (b) summarise the most important and different types of observations associated with thunderstorms which have been made there, and (c) discuss their various geophysical interpretations. The paper describes the main results which have been obtained in four areas of thunderstorm associated atmospheric and geospace science within the context of Earth system science. These relate to the following parameters of atmospheric electricity: the vertical electric potential gradient just above the Earth’s surface and the air–Earth current as well as the point discharge current, Schumann resonance (SR) signals of the Earth-ionosphere cavity at 8, 14 and 20 Hz, transient luminous events (TLEs), and some aspects of the behaviour of the ionosphere. Deductions from these data sets are concerned with the global lightning activity and the conductivity of the air, with diurnal, seasonal, annual and long-term variations of the SR amplitudes and resonant frequencies in terms of migrating thunderstorm centres, with transient SR excitations and with sprites and other TLEs, and with ionospheric disturbances. The paper closes with some thoughts on future research directions based on the observations at NCK and Sopron and the results achieved since the IGY. 相似文献
7.
Rainfall-induced landslide event of May 2010 in the eastern part of the Czech Republic 总被引:3,自引:2,他引:1
Tom��? P��nek Rudolf Br��zdil Jan Klime? Veronika Smolkov�� Jan Hradecky Pavel Zahradn��?ek 《Landslides》2011,8(4):507-516
More than 150 landslides originated in the eastern part of the Czech Republic (region of the Flysch Outer Western Carpathians—hereinafter,
OWC) due to soil saturation caused by antecedent precipitation and long lasting and intensive rainfalls on 16–18 May 2010
(>300 mm as measured by some stations). As a consequence, a multitude of small failures originated 88% of which was smaller
than 104 m2. Most landslides are characterised as shallow (<10 m) or middle–deep (10–30 m) incipient (rather short travel) landslides,
debris slides and soil slips spatially clustered to a geological domain underlain by rather weak thin-bedded flysch and unconsolidated
Quaternary deposits. An exception to this is represented by a kilometre-long rockslide (∼2–3 mil m3) affecting tectonically weakened and weathered claystone/mudstone-dominated flysch on the southern slope of Mt. Girová (the
Beskydy Mountains). The rockslide is one of the largest long runout landslides in the territory of the Czech Republic activated
over the past few decades as it reaches the dimensions of the largest documented Holocene long runout landslides in the Czech
part of the OWC. A majority of the May 2010 landslide events developed inside older (Holocene or historic) landslide terrains,
which points to their spatial persistency and recurrent nature. In spite of the fact that the May 2010 landslide event was
not as destructive as some previous landslide activisation in the OWC region (e.g. July 1997 event), it left many slope failures
at the initial stage of their potential future reactivation. 相似文献
8.
Veronika Gälman Johan Rydberg Andrei Shchukarev Staffan Sjöberg Antonio Martínez-Cortizas Richard Bindler Ingemar Renberg 《Journal of Paleolimnology》2009,42(1):141-153
Easily discernible sediment varves (annual laminations) may be formed in temperate zone lakes, and reflect seasonal changes in the composition of the accumulating material derived from the lake and its catchment (minerogenic and organic material). The appearance of varves may also be influenced by chemical processes. We assessed the role of iron (Fe) and sulfur (S) in the appearance of varves in sediments from Lake Nylandssjön in northern Sweden. We surveyed Fe in the lake water and established whether there is internal transport of Fe within the sediment. We used a unique collection of seven stored freeze cores of varved sediment from the lake, collected from 1979 to 2004. This suite of cores made it possible to follow long-term changes in Fe and S in the sediment caused by processes that occur in the lake bottom when the sediment is ageing. We compared Fe and S concentrations using X-ray fluorescence spectroscopy (XRF) in specific years in the different cores. No diagenetic front was found in the sediment and the data do not suggest that there is substantial vertical transport of Fe and S in the sediment. We also modeled Fe and S based on thermodynamic, limnological, and sediment data from the lake. The model was limited to the five components H+, e?, Fe3+, SO4 2?, H2CO3 and included the formation of solid phases such as Fe(OH)3 (amorphous), FeOOH (aged, microcrystalline), FeS and FeCO3. Modeling showed that there are pe (redox) ranges within which either FeS or Fe(OH)3/FeOOH is the only solid phase present and there are pe ranges within which the two solid phases co-exist, which supports the hypothesis that blackish and grey-brownish layers that occur in the varves were formed at the time of deposition. This creates new possibilities for deciphering high-temporal-resolution environmental information from varves. 相似文献
9.
Veronika S. Heber Rainer Wieler Chad Olinger Donald S. Burnett 《Geochimica et cosmochimica acta》2009,73(24):7414-7432
We present the elemental and isotopic composition of noble gases in the bulk solar wind collected by the NASA Genesis sample return mission. He, Ne, and Ar were analyzed in diamond-like carbon on a silicon substrate (DOS) and 84,86Kr and 129,132Xe in silicon targets by UV laser ablation noble gas mass spectrometry. Solar wind noble gases are quantitatively retained in DOS and with exception of He also in Si as shown by a stepwise heating experiment on a flown DOS target and analyses on other bulk solar wind collector materials. Solar wind data presented here are absolutely calibrated and the error of the standard gas composition is included in stated uncertainties. The isotopic composition of the light noble gases in the bulk solar wind is as follows: 3He/4He: (4.64 ± 0.09) × 10−4, 20Ne/22Ne: 13.78 ± 0.03, 21Ne/22Ne: 0.0329 ± 0.0001, 36Ar/38Ar 5.47 ± 0.01. The elemental composition is: 4He/20Ne: 656 ± 5, and 20Ne/36Ar 42.1 ± 0.3. Genesis provided the first Kr and Xe data on the contemporary bulk solar wind. The preliminary isotope and elemental composition is: 86Kr/84Kr: 0.302 ± 0.003, 129Xe/132Xe: 1.05 ± 0.02, 36Ar/84Kr 2390 ± 150, and 84Kr/132Xe 9.5 ± 1.0. The 3He/4He and the 4He/20Ne ratios in the Genesis DOS target are the highest solar wind values measured in exposed natural and artificial targets. The isotopic composition of the other noble gases and the Kr/Xe ratio obtained in this work agree with data from lunar samples containing “young” (∼100 Ma) solar wind, indicating that solar wind composition has not changed within at least the last 100 Ma. Genesis could provide in many cases more precise data on solar wind composition than any previous experiment. Because of the controlled exposure conditions, Genesis data are also less prone to unrecognized systematic errors than, e.g., lunar sample analyses. The solar wind is the most authentic sample of the solar composition of noble gases, however, the derivation of solar noble gas abundances and isotopic composition using solar wind data requires a better understanding of fractionation processes acting upon solar wind formation. 相似文献
10.
G. Ya. Smolkov V. E. Stepanov V. M. Grigoryev V. G. Banin 《Astrophysics and Space Science》1986,118(1-2):21-30
The Sayan Solar Observatory, the Tunkinskaya Radiophysical Observatory, and the Baikal Astrophysical Observatory of SibIZMIR have been described. Some results of the investigations carried out over the past years have been expounded. Clarifying solar activity mechanisms and the nature of solar magnetic fields, active regions and flares as well as solar wind are their main problems. In the interest of these investigations the Institute has initiated and developed laboratory-scale simulation of plasma processes.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献