On evaluation of depth of soil freezing based on Smos satellite data

The results of a comparative analysis of the brightness temperatures determined from the SMOS satellite and the corresponding depths of soil freezing, measured at weather stations located at the test sites of the Kulunda Plain, are presented. Based on the daily satellite measurement of brightness temperature, the effect of soil freezing on the microwave radiation of the underlying surface was studied. A theoretical calculation of the dependence of soil brightness temperature on the depth of freezing is performed with the model of microwave radiation of a plane-layered inhomogeneous non-isothermal medium. The real parameters of the Kulunda plain soil as well as the climatic characteristics of the sites under study, obtained from the weather stations for the same period, were used as the input parameters of the model. The analysis of satellite, field and model data showed that the evaluation of the depth of soil freezing with satellite microwave radiometry is limited by the need to conduct the contact measurements of physical properties of soil in the areas, for which the SMOS product on the brightness temperature is given.

Propagation Characteristics of Acoustic Wave in Non-Isothermal Earth’s Atmospheres

Acoustic waves are those waves which travel with the speed of sound through a medium. H. Lamb (1909, 1910) had derived a cutoff frequency for stratified and isothermal medium for the propagation of acoustic waves. In order to find the cutoff frequency many methods were introduced after Lamb's work. In this paper, we have chosen the turning point frequency method following Musielak et.al(2006) Routh et. al.(2014) to determine cutoff frequencies for acoustic waves propagating in non-isothermal medium which can be applied to various atmospheres like solar atmosphere, stellar atmosphere, earth's atmosphere etc. Here, we have analytically derived the cutoff frequency and have analyzed and compared with the Lamb's cut-off frequency for earth's troposphere.

The Simulation of Apparent Directional Emissivity in a Three-Dimensional Non-Isothermal Medium by the DRESOR Method

The emissivity as a thermal property plays an important role required for heat transfer calculations and temperature measurement. In an isothermal purely absorption medium, the emissivity can be calculated by the formula, but no general formula for the emissivity will suit the system with scattering of medium and reflection of walls in a coal-fired boiler or an industrial heating furnace. In this study, a new approach was proposed to scale the apparent field directional emissivity by DRESOR method combined with two-color method in a three-dimensional non-isothermal participating medium with reflection of walls. The results obtained by the new method were compared with those calculated by the formula to verify the validity and accuracy of new method in an isothermal purely absorption medium. Then the new method was extended to examine the effect of absorption coefficient, scattering coefficient and reflection of walls on the apparent directional emissivity in the isothermal and non-isothermal cases. It is found that when there is scattering in the medium, the emissivity cannot be equal to the entity, even if the medium is optically thick. In the condition of walls with cold or low temperature, such as in the case of a coal-fired boiler, the apparent emissivity increases with the increase of absorption coefficient and reflectivity of walls, because radiation from hot media plays a dominated role in emissivity in this situation; Meanwhile, in the case of walls with high temperature, such as in the case of an industrial heating furnace in metallurgy or glass melting industry, the apparent emissivity decreases with the increase of absorption coefficient, because the emissivity is mainly determined by the wall radiation in this situation. And when scattering coefficient increases, the apparent emissivity decreases for all isothermal and non-isothermal cases.

Effect of the radiative damping on magnetohydrodynamic waves in an isothermal medium

We investigate the effect of the heat radiation on the reflection and dissipation of upward propagating waves in an isothermal atmosphere. It is shown that the magnetic field produces a totally reflecting layer. Consequently, the atmosphere can be divided into two distinct regions. In the lower region, the solution can be written as a linear combination of an upward and a downward propagating wave, and in the upper region the solution, which satisfies the upper boundary condition, decays exponentially or behaves like a constant. These two regions are connected by a region in which the reflection and transmission of the waves takes place. Moreover, the heat radiation affects only the lower region and changes the sound speed from the adiabatic value to the isothermal one. The reflection coefficient and the attenuation factor of the amplitude of the waves are derived for all values of the heat radiation coefficient. Finally, the conclusions are presented in connection with the heating process of the solar atmosphere.

Development of a Network Analogy and Evaluation of Mean Beam Lengths for Multidimensional Absorbing/Isotropically Scattering Media

Based on Hottel’s zonal formulation, a network analogy is developed for the analysis of radiative transfer in general multidimensional absorbing/isotropically scattering media. Applying the analogy to the analysis of an isothermal medium and assuming that the incoming and outgoing flux density is homogeneous within the medium, the effect of scattering on the evaluation of mean beam lengths is illustrated. Two concepts of mean beam length, an absorption mean beam length (AMBL) and an extinction mean beam length (EMBL), are introduced and shown to be important for the analysis of radiative transfer in practical systems. Both mean beam lengths differ significantly from the conventional mean beam length in systems of moderate and large optical thickness. Relations between AMBL and EMBL and their limiting behavior are developed analytically. Numerical results for a sphere radiating to its surface and an infinite parallel slab radiating to one of its surfaces are presented to demonstrate quantitatively the mathematical behavior of the two mean beam lengths.

Radiative Transfer From a Gray, Absorbing-Emitting, Isothermal Medium in a Conical Enclosure

Radiative heat transfer from an isothermal participating medium in a truncated, conical enclosure is investigated numerically. Two methods of solution are employed: the Monte-Carlo technique and the P1 differential approximation. The solution to the P1 representation is obtained from a control-volume-based discretization of the governing equation. The medium is assumed to be gray and nonscattering, and the absorption coefficient and temperature are uniform throughout the medium. Overall and local heat flux rates at the walls predicted by the P1 method are compared to the quasi-exact results of the Monte-Carlo solution. Results are obtained for a variety of optical thicknesses and cone shapes.

Band Radiation within Diffuse-Walled Enclosures—Part I: Exact Solutions for Simple Enclosures

Exact radiative transfer solutions for an isothermal medium confined within an isothermal enclosure are given for the planar, cylindrical and spherical configurations. The emphasis is upon band radiation and diffuse reflections. Specular reflections are also considered because solutions are easily obtained and are of interest for comparative purposes as well as intrinsic value.