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1.
The previously proposed (Rodin, 2002) method for calculating the microphysical properties of spatially inhomogeneous rarefied aerosol media with mixing using the lowest-order moments of the size distribution is generalized to particle coagulation. We show that when the problem is formulated in terms of moments, all of the solutions admitted by the stochastic coagulation equation lie within a narrow range whose boundaries can be determined by means of quadratic programming. We discuss the choice of an optimal solution within this range and compare the moment method with the results of our computations by the classical finite-difference method using a model of photochemical aerosols in Titan's atmosphere as an example. The moment method allows the efficiency of microphysical computations to be significantly increased by using precomputed low-dimension interpolation tables. It can be used to construct self-consistent models for the globular circulation of planetary atmospheres. 相似文献
2.
P. B. Price D. M. Lowder A. J. Westphal R. D. Wilkes R. A. Brennen V. G. Afanasyev V. V. Akimov V. G. Rodin G. K. Baryshnikov L. A. Gorshkov N. I. Shvets O. S. Tsigankov 《Astrophysics and Space Science》1992,197(1):121-143
The goals of the TREK experiment, now in place on the MIR Space Station, are to resolve and measure the composition of both odd-Z and even-Z cosmic-ray nuclei up to uranium, to measure the isotopic composition of Fe-group nuclei, and to search for transuranic nucleic and exotic particles such as strangelets. To collect tracks of ultraheavy cosmic rays, exterior panels holding an array of BP-1 phosphate glass 1.2m2 in area and 16 plates thick are now mounted outside the Kvant-2 module on MIR. Heaters and relays regulate the temperature of the glass at 25°±5°C. The detectors will record 103 cosmic-ray tracks withZ50 during 2.5 years. An interior panel consisting of an array 0.09 m2 in area and 32 plates thick and mounted on the inside wall of the Soyuz spacecraft (attached to the Space Station) will collect tracks of about 13000 Fe and 500 Ni nuclei. 相似文献
3.
Timing of highly stable millisecond pulsars provides the possibility of independently verifying terrestrial time scales on intervals longer than a year. An ensemble pulsar time scale is constructed based on pulsar timing data obtained on the 64-m Parkes telescope (Australia) in 1995–2010. Optimal Wiener filters were applied to enhance the accuracy of the ensemble time scale. The run of the time-scale difference PTens?TT(BIPM2011) does not exceed 0.8 ± 0.4 μs over the entire studied time interval. The fractional instability of the difference PTens?TT(BIPM2011) over 15 years is σ z = (0.6 ± 1.6) × 10?15, which corresponds to an upper limit for the energy density of the gravitational-wave background Ω g h2 ~ 10?10 and variations in the gravitational potential ~10?15 Hz at the frequency 2 × 10?9 Hz. 相似文献
4.
Dlugach Zh. M. Korablev O. I. Morozhenko A. V. Moroz V. I. Petrova E. V. Rodin A. V. 《Solar System Research》2003,37(1):1-19
Atmospheric aerosols play an important role in forming the Martian climate. However, the basic physical properties of the Martian aerosols are still poorly known; there are many contradictions in their estimates. We present an analytical overview of the published results and potentialities of various methods. We consider mineral dust. Zonally averaged data obtained from mapping IR instruments (TES and IRTM) give the optical thickness of mineral aerosols 9 = 0.05–0.1 in the 9-m band for quite atmospheric conditions. There is a problem of comparing these estimates with those obtained in the visible spectral range. We suggest that the commonly used ratio vis/9 >2 depends on the interpretation and it may actually be smaller. The ratio vis/9 1 is in better agreement with the IRIS data (materials like montmorillonite). If we assume that vis/9 = 1 and take into account the nonspherical particle shape, then the interpretation of ground-based integrated polarimetric observations ( < 0.04) can be reconciled with IR measurements from the orbit. However, for thin layers, the sensitivity of both methods to the optical thickness is poorly understood: on the one hand, polarimetry depends on the cloud cover and, on the other hand, the interpretation of IR measurements requires that the atmospheric temperature profile and the surface temperature and emissivity be precisely known. For quite atmospheric conditions, the local optical-thickness estimates obtained by the Bouguer–Lambert–Beer method and from the sky brightness measured from Viking 1 and 2 and Mars Pathfinder landers are much larger: = 0.3–0.6. Estimates of the contrasts in images from theVikingorbiters yield the same values. Thus, there is still a factor of 3 to 10 difference between different groups of optical-thickness estimates for the quiet atmosphere. This difference is probably explained by the contribution of condensation clouds and/or by local/time variations. 相似文献
5.
The absorption spectrum and thermal radiation fluxes in the lower atmosphere of Venus are calculated using the theory of molecular state interference in the strong collision approximation. Comparison is made with the absorption and radiative transfer calculations in terms of the statistical theory of collisional line broadening and based on an empirical form factor. The calculations show that the line broadening mechanism does not affect the thermal regime of the atmosphere at heights above 60 km, but affects significantly the behavior of the greenhouse effect below the cloud layer. 相似文献
6.
R. O. Kuzmin E. V. Zabalueva I. G. Mitrofanov M. L. Litvak A. V. Rodin W. V. Boynton R. S. Saunders 《Solar System Research》2007,41(2):89-102
The seasonal variation of neutron emissions from Mars in different spectral intervals measured by the HEND neutron detector for the entire Martian year are analyzed. Based on these data, the spatial variations of the neutron emissions from the planet are globally mapped as a function of season, and the dynamics of seasonal variation of neutron fluxes with different energies is analyzed in detail. No differences were found between seasonal regimes of neutron fluxes in different energy ranges in the southern hemisphere of Mars, while the regime of fast neutrons (with higher energies) during the northern winter strongly differs from that during the southern winter. In winter (L s = 270°–330°), the fast neutron fluxes are noticeably reduced in the northern hemisphere (along with the consecutive thickening of the seasonal cap of solid carbon dioxide). This provides evidence of a temporary increase in the water content in the effective layer of neutron generation. According to the obtained estimates, the observed reduction of the flux of fast neutrons in the effective layer corresponds to an increase in the water abundance of up to 5% in the seasonal polar cap (70°–90°N), about 3% at mid-latitudes, and from 1.5 to 2% at low latitudes. The freezing out of atmospheric water at the planetary surface (at middle and high latitudes) and the hydration of salt minerals composing the Martian soil are considered as the main processes responsible for the temporary increase in the water content in the soil and upper layer of the seasonal polar cap. The meridional atmospheric transport of water vapor from the summer southern to the winter northern hemisphere within the Hadley circulation cell is a basic process that delivers water to the subsurface soil layer and ensures the observed scale of the seasonal increase in water abundance. In the summer northern hemisphere, the similar Hadley circulation cell transports mainly dry air masses to the winter southern hemisphere. The point is that the water vapor becomes saturated at lower heights during aphelion, and the bulk of the atmospheric water mass is captured in the near-equatorial cloudy belt and, thus, is only weakly transferred to the southern hemisphere. This phenomenon, known as the Clancy effect, was suggested by Clancy et al. (1996) as a basic mechanism for the explanation of the interhemispheric asymmetry of water storage in permanent polar caps. The asymmetry of seasonal meridional circulation of the Martian atmosphere seems to be another factor determining the asymmetry of the seasonal water redistribution in the “atmosphere-regolith-seasonal polar caps” system, found in the peculiarities of the seasonal regime of the neutron emission of Mars. 相似文献
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8.
Astronomy Reports - In the paper, observation results of the magnetar SGR 1935+2154 at the frequency 111 MHz by the LPA (BSA) FIAN radio telescope are presented. For the search of single... 相似文献
9.
Yu. P. Ilyasov M. Imae Y. Hanado V. V. Oreshko V. A. Potapov A. E. Rodin M. Sekido 《Astronomy Letters》2005,31(1):30-36
We present the results from our timing of the millisecond pulsar B1937+21, performed jointly since 1997 on two radio telescopes: the RT-64 in Kalyazin (Russia) at a frequency of 0.6GHz and RT-34 in Kashima (Japan) at a frequency of 2.15 GHz. The rms value of the pulse time of arrival (TOA) residuals for the pulsar at the barycenter of the Solar system is 1.8 μs (the relative variation is ≈10?14 over the observing period). The TOA residuals are shown to be dominated by white phase noise, which allows this pulsar to be used as an independent time scale keeper. The upper limit for the gravitational background energy density Ωgh2 at frequencies ≈6.5 × 10?9 Hz is estimated to be no higher than 10?6. Based on the long-term timing of the pulsar, we have improved its parameters and accurately determined the dispersion measure and its time variation over the period 1984–2002, which was, on average, ?0.00114(3) pc cm?3 yr?1. 相似文献
10.
Bruno Bézard Anna Fedorova Jean-Loup Bertaux Alexander Rodin Oleg Korablev 《Icarus》2011,216(1):173-183
Observations of the 1.10- and 1.18-μm nightside windows by the SPICAV-IR instrument aboard Venus Express were analyzed to characterize the various sources of gaseous opacity and determine the H2O mole fraction in the lower atmosphere of Venus. We showed that the line profile model of Afanasenko and Rodin (Afanasenko, T.S., Rodin, A.V. [2007]. Astron. Lett. 33, 203–210) underestimates the CO2 absorption in the high-wavelength wing of the 1.18-μm window and we derived an empirical lineshape that matches this wing well. An additional continuum opacity is required to reproduce the variation of the 1.10- and 1.18-μm radiances with surface elevation as observed by the VIRTIS-M instrument aboard Venus Express. A constant absorption coefficient of 0.7 ± 0.2 × 10−9 cm−1 am−2 best reproduces the observed variation. We compared spectra calculated with different CO2 and H2O line lists. We found that the CDSD line list lacks the 5ν1 + ν3 series of CO2 bands, which provide significant opacity in Venus’ deep atmosphere, and we have constructed a composite line list that best reproduces the observations. We also showed for the first time that HDO brings significant absorption at 1140–1190 nm. Using the best representation of the atmospheric opacity we could reach, we retrieved a water vapor mole fraction of ppmv, pertaining to the altitude range 5–25 km. Combined with previous measurements in the 1.74- and 2.3-μm windows, this result provides strong evidence for a uniform H2O profile below 40 km, in agreement with chemical models. 相似文献