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11.
We have quantitatively estimated the contributions of anthropogenic forcing characterized by variations in the atmospheric content of greenhouse gases and of natural variability characterized by the Atlantic Multidecadal Oscillation to the trends of global surface air temperature from observations since the middle of the nineteenth century on the basis of three-component autoregressive models. 相似文献
12.
A.L. Piskarev A.A. Kireev V.A. Savin O.E. Smirnov 《Russian Geology and Geophysics》2018,59(7):803-812
Processing of data from regional geophysical surveys completed in the northern Barents Sea has provided updates to gravity and magnetic databases, structural maps of seismic interfaces, and positions of anomaly sources, which made a basis for 3D density and magnetic models of the crust. The new geological and geophysical results placed constraints on the boundaries between basement blocks formed in different settings and on the contours of deposition zones of different ages in the northeastern Barents Sea. The estimated thicknesses of sedimentary sequences that formed within certain time spans record the deposition history of the region. There is a 20-50 km wide deep suture between two basins of Mesozoic and Paleozoic ages in the eastern part of the region, where pre-Late Triassic reflectors have no clear correlation. The suture slopes eastward at a low angle and corresponds to a paleothrust according to seismic and modeling data. In the basement model, the suture is approximated by a zone of low magnetization and density, which is common to active fault systems. The discovery of the suture has important geological and exploration implications. 相似文献
13.
Astronomy Letters - Based on SDSS data, we consider the fraction of active galactic nuclei among polar-ring galaxies. We have found evidence for an excess of Seyfert galaxies and LINERS among... 相似文献
14.
O.?V.?YushkovaEmail author A.?L.?Gavrik V.?N.?Marchuk V.?V.?Yushkov V.?M.?Smirnov M.?A.?Laptev B.?V.?Chernyshev I.?N.?Dutyshev V.?P.?Lebedev A.?V.?Medvedev A.?A.?Petrukovich 《Solar System Research》2018,52(4):287-300
An overview of radiophysical investigations of the lunar soil and plasma shell by active radar detection with the use of spacecraft is presented. The possibility is analyzed of conducting bistatic measurements using the Irkutsk Incoherent Scattering Radar and the onboard radar system RLK-L which is being developed for the orbital station of the Luna-Resurs mission. 相似文献
15.
S.?N.?KulichkovEmail author O.?Ye.?Popov K.?V.?Avilov I.?P.?Chunchuzov O.?G.?Chkhetiani A.?A.?Smirnov V.?I.?Dubrovin A.?A.?Mishenin 《Izvestiya Atmospheric and Oceanic Physics》2018,54(3):293-303
Results obtained from simulating the propagation of infrasonic waves from the Chelyabinsk meteoroid explosion observed on February 15, 2013, are given. The pseudodifferential parabolic equation (PDPE) method has been used for calculations. Data on infrasonic waves recorded at the IS31 station (Aktyubinsk, Kazakhstan), located 542.7 km from the likely location of the explosion, have been analyzed. Six infrasonic arrivals (isolated clearly defined pulse signals) were recorded. It is shown that the first “fast” arrival (F) corresponds to the propagation of infrasound in a surface acoustic waveguide. The rest of the arrivals (T1–T5) are thermospheric. The agreement between the results of calculations based on the PDPE method and experimental data is satisfactory. The energy E of the explosion has been estimated using two methods. One of these methods is based on the law of conservation of the acoustic pulse I, which is a product of the wave profile area S/2 of the signal under analysis and the distance to its source E I [kt] = 1.38 × 10–10 (I [kg/s])1.482. The other method is based on the relation between the energy of explosion and the dominant period T of recorded signal E T [kt] = 1.02 × (T [s]2/σ)3/2, where σ is the dimensionless distance determining the degree of nonlinear effects during the propagation of sound along ray trajectories. According to the data, the explosion energy E I,T ranges from 1.87 to 32 kt TNT. 相似文献
16.
This paper studies the causes and mechanisms of the formation of extreme anomalies in the tropospheric temperature associated
with the North Atlantic Oscillation (NAO). Our approach is based on understanding that, in the annual cycle, continental-scale
tropospheric temperature anomalies (planetary waves with longitudinal wave numbers of 1–3) can both intensify under the direct
action of heat inflow as an energy source for these anomalies (radiation cooling/heating) and weaken as a result of the destructive
action of heat inflow under temperature advections with the opposite (to the heat inflow) sign [4, 5]. According to the monthly
mean data of the NCEP/NCAR reanalysis over the 40-year period, seasonal air temperature anomalies have been studied at the
level 850 hPa (T
850) in different regions of Eurasia. It has been confirmed that the negative NAO phase in winter is favorable for preserving
negative T
850 anomalies in the east of the continent at this time of year, whereas the positive NAO phase is favorable for negative T
850 anomalies in the west. However, it has been revealed that this dependence was critically violated during the winter seasons
approximately two years before an extreme event. This was explained by the fact that, in those years, the NAO influence on
winter T
850 anomalies was limited. This paper formally considers a certain mechanism of anomalous heat inflow as an energy source for
these anomalies with functions of the formation (intensification) of negative T
850 anomalies in winter and positive T
850 anomalies in summer, as well as with a function of the limitation of the influence of the predominant dynamic mode on some
regions of the continent. It is shown that, in the 1960s, T
850 anomalies with negative NAO indices in the east of the continent were governed by a hypothetic mechanism of heat inflow as
an energy source for anomalies; in 1980s, at prolonged positive NAO indices, T
850 anomalies in the west of the continent could also be governed by this mechanism. This paper, within the accepted degree of
detail, demonstrates the process of limitation of the NAO influence in some years (1966, 1967, 1987, and 1988), which leads
to an unbalance of the anomalies and a possible extreme phenomenon. It is demonstrated that, in some seasons, the anomalies
were not governed by the hypothetic mechanism of the heat inflow under the action of large NAO changes and a complete upset
of the annual cycle of anomalies. Determining the first indicators of the unbalance, which can lead to extreme anomalies,
is shown to be difficult if it is based only on an analysis of winter seasons (as is the case with most of the works) without
invoking the annual trends of the tropospheric temperature and the NAO index. 相似文献
17.
18.
Two extreme ultraviolet (EUV) spectrophotometers flown in December 1978 on Venera 11 and Venera 12 measured the hydrogen Lyman α emission resonantly scattered in the atmosphere of Venus. Measurements were obtained across the dayside of the disk, and in the exosphere up to 50,000 km. They were analyzed with spherically symmetric models for which the radiative transfer equation was solved. The H content of the Venus atmosphere varies from optically thin to moderately thick regions. A shape fit at the bright limb allows one to determine the exospheric temperature Tc and the number density nc independently of the calibration of the instrument or the exact value of the solar flux. The dayside exospheric temperature was measured for the first time in the polar regions, with Tc = 300 ± 25°K for Venera 11 (79°S) and Tc = 275 ± 25°K (59°S) for Venera 12. At the same place, the density is nc = 4?2+3 × 104 atom.cm?3, and the integrated number density Nt from 250 to 110 km (the level of CO2 absorption) is 2.1 × 1012 atom.cm?2, a factor of 3 to 6 lower than that predicted in aeronomical models. This probably indicates that the models should be revised in the content of H-bearing molecules and should include the effect of dynamics. Across the disk the value of Nt decreases smoothly with a total variation of two from the morning side to the afternoon side. Alternately it could be a latitude effect, with less hydrogen in the polar regions. The nonthermal component if clearly seen up to 40,000 km of altitude. It is twice as abundant as at the time of Mariner 10 (solar minimum). Its radial distribution above 4000 km can be simulated by an exospheric distribution with T = 1030K and n = 103 atom.cm?3 at the exobase level. However, there are less hot atoms between 2000 and 4000 km than predicted by an ionospheric source. A by-product of the analysis is a determination of a very high solar Lyman α flux of 7.6 × 1011 photons (cm2 sec Å)?1 at line center (1 AU) in December 1978. 相似文献
19.
Yu. M. Smirnov 《Astronomy Reports》2003,47(3):240-247
We have experimentally studied the excitation of the rhenium atom by collisions with slow monoenergetic electrons and measured 47 excitational cross sections for lines of ReI at an electron energy of 50 eV. Previously published information about the probabilities of radiative transitions of ReI is analyzed. The data for two experimental studies of the ratios Iλ/gA for transitions with a common upper level differ by three orders of magnitude. 相似文献
20.
A heat flow isoline map is presented. Low and relatively constant heat flow has been observed in the old shield areas of the East European Platform (25–40 mW/m2). Increased heat flow (>50 mW/m2) has been found in the Dniepr-Donetz depression. The area south of the East European Platform is characterized by highly variable heat flow (55–100 mW/m2). Some geophysical implications are discussed. 相似文献