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1.
The effects of reflection on the formation of spectral lines is investigated. We have assumed a purely scattering atmosphere and studied how the equivalent widths change due to irradiation from the secondary. Generally, the flux in the lines is increased at all frequency points, the cores of the lines receiving more flux than the wings. Moreover, the proximity of the secondary component changes the equivalent widths considerably. The further away the secondary is from the primary the higher are the equivalent widths. 相似文献
2.
The absorption spectrum and thermal radiation fluxes are calculated for the lower atmosphere of Venus in the far-wing approximation based on the theory of the collisional broadening of spectral lines. The results are in good agreement with the available experimental data. An outgoing thermal radiation flux is about 2.6 W/m2 near the planetary surface. This indicates that free convection significantly contributes to the thermal balance of the lower troposphere. The fluxes obtained in this study were compared to those calculated on the basis of empirical models of the spectral line profile. It was shown that the far wings of the CO2 lines considerably affect the radiative transfer in the transparency windows. This effect becomes weaker when the contribution of the absorption of minor constituents, primarily water vapor, increases. The profiles of absorption lines of minor constituents do not influence the thermal radiation fluxes.__________Translated from Astronomicheskii Vestnik, Vol. 39, No. 3, 2005, pp. 214–226.Original Russian Text Copyright © 2005 by Afanasenko, Rodin. 相似文献
3.
Solar radiation is the primary energy source for many processes in Earth's environment and is responsible for driving the
atmospheric and oceanic circulation. The integrated strength and spectral distribution of solar radiation is modified from
the space-based {Solar {Radiation and {Climate (SORCE) measurements through scattering and absorption processes in the atmosphere
and at the surface. Understanding how these processes perturb the distribution of radiative flux density is essential in determining
the climate response to changes in concentration of various gases and aerosol particles from natural and anthropogenic sources,
as is discerning their associated feedback mechanisms. The past decade has been witness to a tremendous effort to quantify
the absorption of solar radiation by clouds and aerosol particles via airborne and space-based observations. Vastly improved
measurement and modeling capabilities have enhanced our ability to quantify the radiative energy budget, yet gaps persist
in our knowledge of some fundamental variables. This paper reviews some of the many advances in atmospheric solar radiative
transfer as well as those areas where large uncertainties remain. The SORCE mission's primary contribution to the energy budget
studies is the specification of the solar total and spectral irradiance at the top of the atmosphere. 相似文献
4.
Reflection effect in close binaries. III. Distribution of radiation incident from an extended source
A. Peraiah 《Journal of Astrophysics and Astronomy》1983,4(2):151-159
We have studied the effects of irradiation from an extended surface of the secondary component on the atmosphere of the primary.
We have considered an isothermal and purely scattering medium. The resultant radiation field due to irradiation from an extended
surface and self-radiation is different from that due to irradiation from a point source and self-radiation. In the case of
the point source the middle layers of the exposed part of the atmosphere show maximum reflection while in the former case
the reflection gradually decreases from the centre of the component towards the surface of the outermost layers of the atmosphere.
The reflection effect appears to be strongly dependent on the density distribution of the electrons. 相似文献
5.
The law of limb darkening has been calculated when the atmosphere of the primary component is illuminated by the extended
surface of the secondary component in a binary system. The specific intensities calculated at infinity show marked changes
when the plane-parallel approximation is replaced by the assumption of spherical symmetry. The middle portions of the illuminated
surface reflect maximum radiation while the innermost and outermost layers show lesser amount of reflected radiation. 相似文献
6.
M. Srinivasa Rao 《Monthly notices of the Royal Astronomical Society》2006,371(1):303-311
We have studied the effects of partial frequency redistribution function with angle-averaged R II-A in irradiated and moving atmospheres of close binary components. We have considered the atmospheric extension of the primary component to be twice the radius of the primary component in a close binary system. We have considered two cases: (i) when the atmosphere is at rest and (ii) when the atmosphere is moving. In both the cases, we have computed the line profiles along the line of sight for a given optical depth. The irradiation from the secondary component is assumed to be one, five and 10 times the self-radiation. The line fluxes in the line of sight are calculated by using the total source functions due to self-radiation of the primary component and due to the irradiation from the secondary component. We have noted double-peaked emission lines in the case of a static medium and a reduction of emission peaks in the case of velocity field. 相似文献
7.
G. Ponti G. Miniutti A. C. Fabian M. Cappi G. G. C. Palumbo 《Astronomische Nachrichten》2006,327(10):1055-1058
A spectral variability study of the two Narrow Line Seyfert 1 galaxies NGC 4051 and IRAS13224–3809 is presented. Both sources show a high degree of flux and spectral variability. The nuclear emission, lightly absorbed by warm material, has been decomposed into a direct power law emission and an ionized disc reflection plus constant emission from distant material. The ionized disc reflection component does not follow the variations of the primary component. Its flux is linearly correlated with the one of the power law component only at low fluxes, while it is almost constant at medium high‐flux. This behavior is expected when the light bending effect is important. If so, most of the primary emission comes from only a few gravitational radii from the black hole. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
T. Takashima 《Earth, Moon, and Planets》1994,64(1):39-46
To evaluate the effect of the cliff on the radiation field, the upwelling radiation at the top of the atmosphere is computed over the cliff using the reflection and transmission functions derived from the doubling-adding method. The model is defined by the plane-parallel homogeneous atmosphere, which is composed of aerosol and molecules, and is bounded by the top level surface, cliff and low level surface. These surfaces may be assumed to be the Lambertian.In the computational procedure, the equation for the emergent radiation is expanded into a series of radiative interaction modes among atmosphere, surfaces and the cliff. In respective modes, probabilities of respective interactions are firstly evaluated. With the aid of these probabilities, the emergent radiation is calculated using the doubling-adding method for the model atmosphere bounded by the surfaces and cliff, where the above radiative interactions are considered upto twice as large to obtain the enough accuracy of simulation. The multiple scattering is considered. 相似文献
9.
在太阳大气不同层次连续光谱中叠加有丰富的发射线或吸收线,对这些谱线轮廓进行反演分析可以探测太阳大气的化学成分和物理状态.太阳大气的色球及过渡区由于其密度低难以建立热动平衡,建立相应的大气模型需要采用非局部热动平衡(Non-Local Thermodynamic Equilibrium,N-LTE)理论.根据相对偏离因子计算来研究太阳中低层大气偏离局部热动平衡(Local Thermodynamic Equilibrium,LTE)分布的情况.首先对日全食观测过程中得到色球和过渡区不同高度形成的两条光谱数据进行反演,得到确定观测谱线的参数信息,如连续谱源函数、谱线源函数、多普勒宽度和由此推出的等效动力学温度;根据这些反演出的谱线参量计算出二维视场内每个空间采样点偏离LTE状态的定量结果;其次,根据用于观测的积分视场单元光纤排布阵列重构出辐射强度、等效动力学温度和相对偏离因子二维分布.结果显示:在局部小区域,温度分布和相对偏离因子的分布存在较强相关性,而与辐射强度分布无明显相关.从两条谱线导出的等效温度和相对偏离因子分布存在明显的差异.这两种二维分布揭示出太阳大气某些小尺度区域具有较强的结构性和复杂性,为进一步理解太阳中低层大气物理提供了一种新的视角. 相似文献
10.
A method of computing the diffuse reflection and transmission radiation by an inhomogeneous, plane-parallel planetary atmosphere with internal emission source is discussed by use of the adding method. If the atmosphere is simulated by a number of homogeneous sub-layers, the radiation diffusely reflected or transmitted by the atmosphere can be expressed in terms of the reflection and transmission matrices of the radiation of sub-layers. The diffusely transmitted radiation due to the internal emission source can be also easily computed in the same manner. These equations for the emergent radiation are in a quite general form and are applicable to radiative transfer in the atmosphere in the region from ultraviolet to infrared radiation. With this method, the tiresome treatment due to the polarity effect of radiation is overcome. 相似文献
11.
Studies of eclipsing binaries with Hipparcos parallaxes are found to define a radiative flux relation for main sequence stars
in the spectral range from B6 – F0which is about as well as to the stars derived from angular diameters. At lower temperatures
the fluxes of the components fall below this curve which is caused due to the large intrinsic variations and starspots. From
the present analysis it is found that the secondary component of UV Piscium, a late type eclipsing binary, is a normal K3V
star and it fits the radiative flux-colour relation quite satisfactorily. This is explained due to the reliable values of
the fluxes and colours derived from the clean light curves (light curves obtained after removing the effect of the distortion
wave). However, the primary component which is also responsible for the intrinsic variations and starspots continue to deviate
from this curve.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
A new way is adopted for the evaluation of the upwelling radiation from atmosphere bounded by two half-Lambert surfaces. The atmosphere is assumed to be homogeneous, and is composed of aerosol, molecules, and absorbent gases, where the model aerosol is of the oceanic and water soluble types.In the computational procedure, an iterative doubling-adding equation is expanded into a series of the radiative interaction modes between atmosphere and surface. Next, a probability of radiation interacting with respective half surfaces is calculated based on the assumption of single-scattering in the atmosphere. On the basis of this probability, the emergent radiation at the top of the atmosphere is approximately calculated by considering the radiative intractions to be twice as large. The effect of the multiple-scattering is fully taken into account. A numerical simulation exhibits the extraordinary effect near the two half-surface boundary of different albedoes. The effect of the other half-surface on the radiance decreases monotonically with the distance from the boundary. The present new version enable us to quantitatively discuss radiative transfer near the boundary of two half-surfaces even if the optical thickness is large and (or) surface albedo is great. 相似文献
13.
David Vokrouhlický Paolo Farinella David Lucchesi 《Celestial Mechanics and Dynamical Astronomy》1993,57(1-2):225-244
The force due to radiation pressure on a satellite of arbitrary shape is written in a general form within a formalism similar to that used in the theory of radiative transfer in atmospheres. Then the corresponding integrals are evaluated for the simple case of a spherically symmetric satellite, and applied to model the perturbation due to the Earth-reflected radiation flux on LAGEOS. For this purpose, the optical behaviour of the Earth's surface and atmosphere is described as a combination of Lambertian diffusion (continents), partial specular reflection consistent with Fresnel law (oceans) and anisotropic diffusion according to Chandrasekhar's radiative transfer theory (clouds). The in-plane Gauss componentsT andS vs. mean anomaly are computed for a simple orbital geometry and for different models of the Earth's optical properties. A sensitive dependence is found on the assumed cloud distribution, with significant perturbations possibly arising from oceanic specular reflection when the satellite is close to the Earth's shadow boundaries.On leave from Astronomical Institute, Charles University, védská 8, 15000 Prague 5, Czechoslovakia 相似文献
14.
In this paper we present a new definition and its analytic expressions for the mean optical depth and the mean contribution function of spectral lines in a turbulent atmosphere. These mean values are based on the radiative transfer equation and thus satisfy the general properties of the radiation field. They can be used to study the line formation process in turbulent atmospheres. 相似文献
15.
Peter W. Blum 《Planetary and Space Science》1968,16(12):1427-1440
Since 1958 it is known that there exists a response time of the upper atmosphere to changes in solar activity. This response time is best described as the lag between the 27-day variation of solar decimeter flux and the observed density changes of the upper atmosphere. Roemer obtained as a mean observational value for this lag 1.0 ± 0.12 days. Volland's simplified version of the Harris-Priester model of the upper atmosphere is used to calculate the delay which can be expected from theory. Only the effect of solar EUV radiation is taken into account. A possible influence of the corpuscular component of the solar radiation is not included in our estimate.
The calculations are carried out for the Harris-Priester model with solar activity index and a variation of . The resulting delay is 0.6 days. The calculated amplitude of the variations of the diurnal average temperatures during the solar 27-days cycle is in very good agreement with Jacchia's empirical formula. 相似文献
16.
Net radiative flux measurements by instruments on the Pioneer Venus Day, North, and Night probes are too large below 30 km to be consistent with present estimates of atmospheric opacity. We evaluate the only known mechanisms which could potentially have caused significant errors in the deep atmosphere, namely, (1) radiation field perturbations behind each probe due to its thermal wake, (2) cloud particle deposition on the sensor windows, and (3) thermal perturbations within the radiation sensor produced by gas flow through the sensor window retainers. Thermal analysis of the wake effect shows that temperature perturbations are not large enough to produce significant flux perturbations when gas opacity and sensor field-of-view characteristics are taken into account. The particle deposition effect is rejected because it requires a signature in the measured radiation profile which is not observed. The absence of such a feature also implies that mode 3 cloud particles are either not sulfuric acid or are far less numerous than previously reported. We find that the third mechanism is the most likely source of the large net flux measurements. However, this error is not sufficiently constrained by laboratory data to allow rigorous corrections to the measured flux profiles. If we use radiative transfer calculations to constrain the fluxes at 14 km and limited laboratory data to estimate the altitude dependence of the error, then we obtain a plausible set of corrected flux profiles which are roughly consistent with reasonable H2O mixing ratios below the clouds. 相似文献
17.
G. Lamer P. Uttley I. M. MHardy 《Monthly notices of the Royal Astronomical Society》2000,319(3):949-955
We report on observations of the narrow-line Seyfert galaxy NGC 5506 with the Rossi X-ray Timing Explorer . The observations cover a time interval of ∼1000 d during which the source showed strong flux and spectral variability. The spectrum clearly shows iron fluorescence emission at 6.4 keV and significant reflection features. Both the equivalent width of the iron line and the relative strength of the reflected continuum are higher during low flux states. The variability of the reflection features can be explained by the presence of two reflected components: one that responds rapidly to flux changes of the primary continuum and a second, slowly variable, component originating from a distant reflector, e.g. a molecular torus. 相似文献
18.
19.
We study the relationship between full-disk solar radiative flux at different wavelengths and average solar photospheric magnetic-flux
density, using daily measurements from the Kitt Peak magnetograph and other instruments extending over one or more solar cycles.
We use two different statistical methods to determine the underlying nature of these flux – flux relationships. First, we
use statistical correlation and regression analysis and show that the relationships are not monotonic for total solar irradiance
and for continuum radiation from the photosphere, but are approximately linear for chromospheric and coronal radiation. Second,
we use signal theory to examine the flux – flux relationships for a temporal component. We find that a well-defined temporal
component exists and accounts for some of the variance in the data. This temporal component arises because active regions
with high magnetic-field strength evolve, breaking up into small-scale magnetic elements with low field strength, and radiative
and magnetic fluxes are sensitive to different active-region components. We generate empirical models that relate radiative
flux to magnetic flux, allowing us to predict spectral-irradiance variations from observations of disk-averaged magnetic-flux
density. In most cases, the model reconstructions can account for 85 – 90% of the variability of the radiative flux from the
chromosphere and corona. Our results are important for understanding the relationship between magnetic and radiative measures
of solar and stellar variability. 相似文献
20.
In this work, we describe an analysis of the internal solar radiation fields in Saturn's atmosphere. The aim of this paper is to study how the solar radiation flux in optical wavelengths (0.25-1.0 μm) is attenuated, primarily by the effect of the aerosols located close to the tropopause level, retrieving also the corresponding solar heating rates. We use a doubling-adding method and previous results on the vertical cloud and haze structure of Saturn's atmosphere. Our study shows that the maximum penetration level (∼250 mbar) for these wavelengths is substantially higher than previously expected because of the huge optical thickness of the tropospheric haze described in all vertical cloud structure models. We compare our results with previous estimates and parameterizations for seasonal climate models and propose a new approach for future models, with an intense and concentrated heating rate close to the top level of the tropospheric haze. Given that our spectral range accounts for about the 70% of the total solar flux, and using previous estimates for the penetration levels of infrared radiation in Saturn's atmosphere, we conclude solar radiation effect is negligible at levels below 600 mbar. This result is fundamental for understanding the role of solar radiation in the general atmospheric circulation of Saturn. 相似文献