Pub Date : 2024-12-21DOI: 10.1016/j.jqsrt.2024.109328
J.X. Wang, Z.G. Xu, F.Q. Zhang
Graphene grating structures have potential in enhancing near-field radiative heat transfer because of their anisotropic properties and single-layer graphene grating structures have shown excellent capability for thermal modulation in magnetic fields. In this study, a theoretical model for the near-field radiative heat transfer under the influence of a magnetic field in twisted bilayer graphene grating structures is proposed, in which there exists a rotation angle between bilayer graphene gratings. The emitter and absorber are mirror images of each other. The combined effect of the magnetic field and graphene chemical potentials on modulating near-field radiative heat transfer is investigated. The effect of the graphene grating filling factor on the surface state and the near-field radiative heat transfer is discussed. By manipulating the rotation angle of the graphene gratings, the magnetic field enhances thermal modulation. The hyperbolic and elliptic surface plasmon polaritons of the graphene gratings undergo topological transitions as the rotation angle increases.
{"title":"Near field radiative heat transfer in twisted bilayer graphene grating structures based on magnetic modulation","authors":"J.X. Wang, Z.G. Xu, F.Q. Zhang","doi":"10.1016/j.jqsrt.2024.109328","DOIUrl":"10.1016/j.jqsrt.2024.109328","url":null,"abstract":"<div><div>Graphene grating structures have potential in enhancing near-field radiative heat transfer because of their anisotropic properties and single-layer graphene grating structures have shown excellent capability for thermal modulation in magnetic fields. In this study, a theoretical model for the near-field radiative heat transfer under the influence of a magnetic field in twisted bilayer graphene grating structures is proposed, in which there exists a rotation angle between bilayer graphene gratings. The emitter and absorber are mirror images of each other. The combined effect of the magnetic field and graphene chemical potentials on modulating near-field radiative heat transfer is investigated. The effect of the graphene grating filling factor on the surface state and the near-field radiative heat transfer is discussed. By manipulating the rotation angle of the graphene gratings, the magnetic field enhances thermal modulation. The hyperbolic and elliptic surface plasmon polaritons of the graphene gratings undergo topological transitions as the rotation angle increases.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"333 ","pages":"Article 109328"},"PeriodicalIF":2.3,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-21DOI: 10.1016/j.jqsrt.2024.109331
Claudia D. Morello , Robert A. West , Matthew J. Berg
Enceladus, the sixth largest moon of Saturn, is known to be a geologically active icy body. Observations by NASA's Cassini spacecraft show that Enceladus has cryovolcanoes on its south pole as well as a global subsurface ocean hidden beneath its frozen crust. Photographs from NASA's Cassini Spacecraft during flybys of Enceladus document Enceladus's surface and the cryovolcano plumes. It is known that larger particles ejected from the cryovolcanoes deposit on the surface, while smaller particles escape into Saturn's E-ring. Cassini observations of the sunlight scattered by the plume particles on the surface may provide information about the plume composition and potentially the dynamics of the ocean below. This work presents Enceladus’ disk-averaged degree of linear polarization (DoLP), which has yet to be analyzed, and compares it to spherical, spheroidal, cylindrical, and hexagonal ice particles simulated by light scattering codes ADDA and T-Matrix using a multiple-scattering approximation. The Pearson correlation coefficient is used to quantify the fit of each morphology to the surface polarization data in the GRN (569 nm) and MT2 (727 nm) wavelength filters. The polarization of Enceladus’ surface implies the particles are likely non-spherical, and possibly occur in a narrow size distribution near a mean of two microns in radius.
{"title":"Polarization Analysis of Enceladus’ Surface","authors":"Claudia D. Morello , Robert A. West , Matthew J. Berg","doi":"10.1016/j.jqsrt.2024.109331","DOIUrl":"10.1016/j.jqsrt.2024.109331","url":null,"abstract":"<div><div>Enceladus, the sixth largest moon of Saturn, is known to be a geologically active icy body. Observations by NASA's Cassini spacecraft show that Enceladus has cryovolcanoes on its south pole as well as a global subsurface ocean hidden beneath its frozen crust. Photographs from NASA's Cassini Spacecraft during flybys of Enceladus document Enceladus's surface and the cryovolcano plumes. It is known that larger particles ejected from the cryovolcanoes deposit on the surface, while smaller particles escape into Saturn's E-ring. Cassini observations of the sunlight scattered by the plume particles on the surface may provide information about the plume composition and potentially the dynamics of the ocean below. This work presents Enceladus’ disk-averaged degree of linear polarization (DoLP), which has yet to be analyzed, and compares it to spherical, spheroidal, cylindrical, and hexagonal ice particles simulated by light scattering codes ADDA and T-Matrix using a multiple-scattering approximation. The Pearson correlation coefficient is used to quantify the fit of each morphology to the surface polarization data in the GRN (569 nm) and MT2 (727 nm) wavelength filters. The polarization of Enceladus’ surface implies the particles are likely non-spherical, and possibly occur in a narrow size distribution near a mean of two microns in radius.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"333 ","pages":"Article 109331"},"PeriodicalIF":2.3,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-19DOI: 10.1016/j.jqsrt.2024.109310
Nigar Asadova , Karim Achouri , Kristian Arjas , Baptiste Auguié , Roland Aydin , Alexandre Baron , Dominik Beutel , Bernd Bodermann , Kaoutar Boussaoud , Sven Burger , Minseok Choi , Krzysztof M. Czajkowski , Andrey B. Evlyukhin , Atefeh Fazel-Najafabadi , Ivan Fernandez-Corbaton , Puneet Garg , David Globosits , Ulrich Hohenester , Hongyoon Kim , Seokwoo Kim , Grigorios P. Zouros
The transition matrix, frequently abbreviated as T-matrix, contains the complete information in a linear approximation of how a spatially localized object scatters an incident field. The T-matrix is used to study the scattering response of an isolated object and describes the optical response of complex photonic materials made from ensembles of individual objects. T-matrices of certain common structures, potentially, have been repeatedly calculated all over the world again and again. This is not necessary and constitutes a major challenge for various reasons. First, the resources spent on their computation represent an unsustainable financial and ecological burden. Second, with the onset of machine learning, data is the gold of our era, and it should be freely available to everybody to address novel scientific challenges. Finally, the possibility of reproducing simulations could tremendously improve if the considered T-matrices could be shared. To address these challenges, we found it important to agree on a common data format for T-matrices and to enable their collection from different sources and distribution. This document aims to develop the specifications for storing T-matrices and associated metadata. The specifications should allow maximum freedom to accommodate as many use cases as possible without introducing any ambiguity in the stored data. The common format will assist in setting up a public database of T-matrices.
{"title":"T-matrix representation of optical scattering response: Suggestion for a data format","authors":"Nigar Asadova , Karim Achouri , Kristian Arjas , Baptiste Auguié , Roland Aydin , Alexandre Baron , Dominik Beutel , Bernd Bodermann , Kaoutar Boussaoud , Sven Burger , Minseok Choi , Krzysztof M. Czajkowski , Andrey B. Evlyukhin , Atefeh Fazel-Najafabadi , Ivan Fernandez-Corbaton , Puneet Garg , David Globosits , Ulrich Hohenester , Hongyoon Kim , Seokwoo Kim , Grigorios P. Zouros","doi":"10.1016/j.jqsrt.2024.109310","DOIUrl":"10.1016/j.jqsrt.2024.109310","url":null,"abstract":"<div><div>The transition matrix, frequently abbreviated as T-matrix, contains the complete information in a linear approximation of how a spatially localized object scatters an incident field. The T-matrix is used to study the scattering response of an isolated object and describes the optical response of complex photonic materials made from ensembles of individual objects. T-matrices of certain common structures, potentially, have been repeatedly calculated all over the world again and again. This is not necessary and constitutes a major challenge for various reasons. First, the resources spent on their computation represent an unsustainable financial and ecological burden. Second, with the onset of machine learning, data is the gold of our era, and it should be freely available to everybody to address novel scientific challenges. Finally, the possibility of reproducing simulations could tremendously improve if the considered T-matrices could be shared. To address these challenges, we found it important to agree on a common data format for T-matrices and to enable their collection from different sources and distribution. This document aims to develop the specifications for storing T-matrices and associated metadata. The specifications should allow maximum freedom to accommodate as many use cases as possible without introducing any ambiguity in the stored data. The common format will assist in setting up a public database of T-matrices.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"333 ","pages":"Article 109310"},"PeriodicalIF":2.3,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-18DOI: 10.1016/j.jqsrt.2024.109325
Yifan Sun , Guoliang Chen , Qingze Chen , Haoyang Fu , Benzhi Min , Zhengwei Tao , Tongtong Yue , Junming Zhao , Jun Qiu
Structure-engineering has proven successful in enhancing the thermochromic properties of VO2-based film for smart thermal management under dynamic thermal loads. However, traditional multilayer structures based on interlayer interference and grating structures based on resonance effect exhibit certain wavelength selectivity, thereby hindering broadband absorption. This limitation constrains the improvement of high temperature integrated emissivity (εH), posing great challenges for achieving greater average emissivity tunability (Δε=εH-εL). In this work, we propose a VO2-based 3D pyramid structured film by combining the multilayer structure with the grating structure, achieving an unprecedented high emissivity tunability Δε reaching 0.68. Based on the Magneto-polaron (MP) resonance effect, high absorption over a wide spectral range at high temperature is achieved, with εH of 0.954. Through optimizing the VO2 thickness δ to 30 nm and tilt angle β to 80° respectively, we achieve optimal thermochromic performance of the film. Compared with conventional multilayer and grating regimes, the pyramid textured structure proposed in this work demonstrates a larger design space, which can be a reference for the design and optimization of spacecraft thermal control skin.
{"title":"Pyramid-structured VO2-based thin films with large emissivity tunability for thermochromic radiators","authors":"Yifan Sun , Guoliang Chen , Qingze Chen , Haoyang Fu , Benzhi Min , Zhengwei Tao , Tongtong Yue , Junming Zhao , Jun Qiu","doi":"10.1016/j.jqsrt.2024.109325","DOIUrl":"10.1016/j.jqsrt.2024.109325","url":null,"abstract":"<div><div>Structure-engineering has proven successful in enhancing the thermochromic properties of VO<sub>2</sub>-based film for smart thermal management under dynamic thermal loads. However, traditional multilayer structures based on interlayer interference and grating structures based on resonance effect exhibit certain wavelength selectivity, thereby hindering broadband absorption. This limitation constrains the improvement of high temperature integrated emissivity (<em>ε</em><sub>H</sub>), posing great challenges for achieving greater average emissivity tunability (Δ<em>ε</em>=<em>ε</em><sub>H</sub>-<em>ε</em><sub>L</sub>). In this work, we propose a VO<sub>2</sub>-based 3D pyramid structured film by combining the multilayer structure with the grating structure, achieving an unprecedented high emissivity tunability Δ<em>ε</em> reaching 0.68. Based on the Magneto-polaron (MP) resonance effect, high absorption over a wide spectral range at high temperature is achieved, with <em>ε</em><sub>H</sub> of 0.954. Through optimizing the VO<sub>2</sub> thickness <em>δ</em> to 30 nm and tilt angle <em>β</em> to 80° respectively, we achieve optimal thermochromic performance of the film. Compared with conventional multilayer and grating regimes, the pyramid textured structure proposed in this work demonstrates a larger design space, which can be a reference for the design and optimization of spacecraft thermal control skin.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"333 ","pages":"Article 109325"},"PeriodicalIF":2.3,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-17DOI: 10.1016/j.jqsrt.2024.109320
David Santalices , Juan Meléndez , Susana Briz
Periodic fluctuations in the incoming spectrum to a Fourier-transform infrared (FTIR) spectrometer often result in spectral artifacts that can compromise quantitative measurements. This study presents a novel method that relaxes the conventional assumption of uniform fluctuations across all frequencies, by modeling the radiance fluctuations with a Fourier series expansion with wavenumber-dependent coefficients. By limiting the incoming spectral bandwidth with an interference filter, it is possible to retrieve the artifact-free average spectrum and to obtain the temporal evolution of the incident radiance. Experimental validation was conducted with transmittance measurements on a methane gas sample whose column density was periodically modulated. This method expands FTIR capabilities, particularly for applications involving fluctuating gases, and enhances the potential for time-resolved analysis in complex environments.
{"title":"Analysis of periodic temporal changes in the spectral signature of IR sources by modeling of spectral artifacts in FTIR systems","authors":"David Santalices , Juan Meléndez , Susana Briz","doi":"10.1016/j.jqsrt.2024.109320","DOIUrl":"10.1016/j.jqsrt.2024.109320","url":null,"abstract":"<div><div>Periodic fluctuations in the incoming spectrum to a Fourier-transform infrared (FTIR) spectrometer often result in spectral artifacts that can compromise quantitative measurements. This study presents a novel method that relaxes the conventional assumption of uniform fluctuations across all frequencies, by modeling the radiance fluctuations with a Fourier series expansion with wavenumber-dependent coefficients. By limiting the incoming spectral bandwidth with an interference filter, it is possible to retrieve the artifact-free average spectrum and to obtain the temporal evolution of the incident radiance. Experimental validation was conducted with transmittance measurements on a methane gas sample whose column density was periodically modulated. This method expands FTIR capabilities, particularly for applications involving fluctuating gases, and enhances the potential for time-resolved analysis in complex environments.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"333 ","pages":"Article 109320"},"PeriodicalIF":2.3,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-15DOI: 10.1016/j.jqsrt.2024.109318
Netai Das , Arijit Ghoshal , Yew Kam Ho
The existence and the behaviour of the resonance states in the scattering of electrons from the hydrogen atoms under semi-classical plasma environments are investigated. The organized effect of the plasma charged particles is modelled by a pseudopotential which takes care of the quantum mechanical effect of diffraction at short distances as well as the collective effect of the plasma particles by means of two adjustable parameters, namely the de Broglie wavelength and the screening parameter . An extensive square-integrable basis set is employed within the framework of the stabilization method to determine the S-wave resonance states in the e-H system. In particular, the emergence of three S-wave singlet resonance states is identified by noting the stabilized energy levels, whereas the energy and the width of those states are computed from the fitting of the density of the states with the Lorentzian form. The results for the plasma-free case are in good agreement with the established results in the literature. A comprehensive study is made on the changes in the energy and width of the resonance states as a result of variation in at a given .
{"title":"Electron scattering from hydrogen atom in dense semi-classical hydrogen plasma: S-wave resonance states","authors":"Netai Das , Arijit Ghoshal , Yew Kam Ho","doi":"10.1016/j.jqsrt.2024.109318","DOIUrl":"10.1016/j.jqsrt.2024.109318","url":null,"abstract":"<div><div>The existence and the behaviour of the resonance states in the scattering of electrons from the hydrogen atoms under semi-classical plasma environments are investigated. The organized effect of the plasma charged particles is modelled by a pseudopotential which takes care of the quantum mechanical effect of diffraction at short distances as well as the collective effect of the plasma particles by means of two adjustable parameters, namely the de Broglie wavelength <span><math><mi>λ</mi></math></span> and the screening parameter <span><math><mi>κ</mi></math></span>. An extensive square-integrable basis set is employed within the framework of the stabilization method to determine the S-wave resonance states in the e-H system. In particular, the emergence of three S-wave singlet resonance states is identified by noting the stabilized energy levels, whereas the energy and the width of those states are computed from the fitting of the density of the states with the Lorentzian form. The results for the plasma-free case are in good agreement with the established results in the literature. A comprehensive study is made on the changes in the energy and width of the resonance states as a result of variation in <span><math><mi>λ</mi></math></span> at a given <span><math><mi>κ</mi></math></span>.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"333 ","pages":"Article 109318"},"PeriodicalIF":2.3,"publicationDate":"2024-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-14DOI: 10.1016/j.jqsrt.2024.109323
Olga Shefer
For set of crystals with and without taking into account nonsphericity and preferential orientation, there are presented the calculation results that generalize the features of the spectral behavior of the extinction efficiency factor of radiant energy. The influence of various physico-chemical characteristics of scatterers on extinction is demonstrated. The scheme is proposed for comparative analysis of the extinction coefficient of visible and infrared radiation for different components of ice cloud. Considering a medium containing methane and large ice plates, there is demonstrated the scheme to estimate cooperative and separated contributions of dispersed and gas components to the total extinction by the mixture.
{"title":"Separated and cooperative influence of components of ice cloud on total extinction of optical radiation","authors":"Olga Shefer","doi":"10.1016/j.jqsrt.2024.109323","DOIUrl":"10.1016/j.jqsrt.2024.109323","url":null,"abstract":"<div><div>For set of crystals with and without taking into account nonsphericity and preferential orientation, there are presented the calculation results that generalize the features of the spectral behavior of the extinction efficiency factor of radiant energy. The influence of various physico-chemical characteristics of scatterers on extinction is demonstrated. The scheme is proposed for comparative analysis of the extinction coefficient of visible and infrared radiation for different components of ice cloud. Considering a medium containing methane and large ice plates, there is demonstrated the scheme to estimate cooperative and separated contributions of dispersed and gas components to the total extinction by the mixture.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"333 ","pages":"Article 109323"},"PeriodicalIF":2.3,"publicationDate":"2024-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-10DOI: 10.1016/j.jqsrt.2024.109321
Adam Pastorek , Peter Bernath
We present a comprehensive data analysis of coincident solar occultation data captured by the ACE satellite, alongside the atmospheric river database derived from MERRA-2 reanalysis through the ARTMIP (Atmospheric River Tracking Method Intercomparison Project) initiative. Our investigation, comparing an atmospheric river catalogue by Guan and Waliser (2015) with experimental ACE data, reveals significant differences in altitude-dependent volume-mixing ratios (VMRs) of several molecules (particularly H2O, HNO3, and O3). These differences are observed in pairs of ACE observations that are closely matched in time and location, with one point falling within an identified atmospheric river and the other outside. Additionally, we demonstrate that these differences in VMR profiles are not attributable to random atmospheric turbulence. This is achieved by contrasting our findings with a randomized set of paired ACE observations, where both data points are situated outside of atmospheric rivers. The obtained results corroborate atmospheric mixing between the troposphere and stratosphere during the passage of an atmospheric river through a specific location. Our findings demonstrate the utility of ACE satellite data in observing atmospheric phenomena associated with atmospheric rivers.
{"title":"Comparison of atmospheric river-related phenomena with ACE satellite data","authors":"Adam Pastorek , Peter Bernath","doi":"10.1016/j.jqsrt.2024.109321","DOIUrl":"10.1016/j.jqsrt.2024.109321","url":null,"abstract":"<div><div>We present a comprehensive data analysis of coincident solar occultation data captured by the ACE satellite, alongside the atmospheric river database derived from MERRA-2 reanalysis through the ARTMIP (Atmospheric River Tracking Method Intercomparison Project) initiative. Our investigation, comparing an atmospheric river catalogue by Guan and Waliser (2015) with experimental ACE data, reveals significant differences in altitude-dependent volume-mixing ratios (VMRs) of several molecules (particularly H<sub>2</sub>O, HNO<sub>3</sub>, and O<sub>3</sub>). These differences are observed in pairs of ACE observations that are closely matched in time and location, with one point falling within an identified atmospheric river and the other outside. Additionally, we demonstrate that these differences in VMR profiles are not attributable to random atmospheric turbulence. This is achieved by contrasting our findings with a randomized set of paired ACE observations, where both data points are situated outside of atmospheric rivers. The obtained results corroborate atmospheric mixing between the troposphere and stratosphere during the passage of an atmospheric river through a specific location. Our findings demonstrate the utility of ACE satellite data in observing atmospheric phenomena associated with atmospheric rivers.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"333 ","pages":"Article 109321"},"PeriodicalIF":2.3,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-10DOI: 10.1016/j.jqsrt.2024.109311
Vadim A. Markel , Manabu Machida , John C. Schotland
We consider the collision expansion of the Green’s function of the radiative transport equation (RTE) in an infinite medium. Analytical expressions in terms of quadratures of the most simple form are given for all orders of the expansion. Singularities of the Green’s function are considered in detail. While it is well known that the zeroth and first terms in the expansion are singular (and proportional to delta functions), we show that the second order term contains a logarithmic singularity. All higher-order terms are regular. We further establish a relation between the Green’s function and the signal measured by a collimated detector. In the presence of singularities, this relation is not always obvious and, at second order, it cannot be stated in a form that is independent of the acceptance angle of the detector. We also consider the density and energy current. Theoretical results are supported by Monte-Carlo simulations.
{"title":"Collision expansion for the radiative transport equation: Analytical results and numerical simulations","authors":"Vadim A. Markel , Manabu Machida , John C. Schotland","doi":"10.1016/j.jqsrt.2024.109311","DOIUrl":"10.1016/j.jqsrt.2024.109311","url":null,"abstract":"<div><div>We consider the collision expansion of the Green’s function of the radiative transport equation (RTE) in an infinite medium. Analytical expressions in terms of quadratures of the most simple form are given for all orders of the expansion. Singularities of the Green’s function are considered in detail. While it is well known that the zeroth and first terms in the expansion are singular (and proportional to delta functions), we show that the second order term contains a logarithmic singularity. All higher-order terms are regular. We further establish a relation between the Green’s function and the signal measured by a collimated detector. In the presence of singularities, this relation is not always obvious and, at second order, it cannot be stated in a form that is independent of the acceptance angle of the detector. We also consider the density and energy current. Theoretical results are supported by Monte-Carlo simulations.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"333 ","pages":"Article 109311"},"PeriodicalIF":2.3,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Empirical and semi-empirical models of the continua absorption are still ubiquitously used in atmospheric science and applications despite almost a hundred-years-long persistent theoretical and experimental investigation of the continuum' nature. Based on the empirical knowledge accumulated to-date about the water vapor continuum we propose a physically sound continuum model for practical applications in the subterahertz frequency range (0-1 THz). Our model interpret the water vapor continuum in terms of a combination of various contributions owed to bimolecular absorption. The self-continuum component is presented in the model as a sum of the contributions from absorption by bound and quasibound dimers, which are evaluated with the help of the water vapor second virial coefficient and existing ab initio simulation of the water dimer absorption. The contribution from the far wings of the water monomer resonant lines is taken into account by virtue of a simple analytical function approximating available empirical data. The foreign-continuum component of absorption is taken in a conventional empirical form. The values of its numerical coefficients are updated to achieve better agreement with results of laboratory measurements in the sub-THz range. We demonstrate that our new model is in good agreement with modern versions of atmospheric propagation models. However, the atmospheric brightness temperature calculated using our new model systematically deviates from the results obtained with its empirical version. The deviation amounts up to several Kelvins in the microwindows between resonant water lines.
{"title":"Atmospheric water vapor continuum model for the sub-THz range","authors":"M.Yu. Tretyakov , T.A. Galanina , A.O. Koroleva , D.S. Makarov , D.N. Chistikov , A.A. Finenko , A.A. Vigasin","doi":"10.1016/j.jqsrt.2024.109319","DOIUrl":"10.1016/j.jqsrt.2024.109319","url":null,"abstract":"<div><div>Empirical and semi-empirical models of the continua absorption are still ubiquitously used in atmospheric science and applications despite almost a hundred-years-long persistent theoretical and experimental investigation of the continuum' nature. Based on the empirical knowledge accumulated to-date about the water vapor continuum we propose a physically sound continuum model for practical applications in the subterahertz frequency range (0-1 THz). Our model interpret the water vapor continuum in terms of a combination of various contributions owed to bimolecular absorption. The self-continuum component is presented in the model as a sum of the contributions from absorption by bound and quasibound dimers, which are evaluated with the help of the water vapor second virial coefficient and existing <em>ab initio</em> simulation of the water dimer absorption. The contribution from the far wings of the water monomer resonant lines is taken into account by virtue of a simple analytical function approximating available empirical data. The foreign-continuum component of absorption is taken in a conventional empirical form. The values of its numerical coefficients are updated to achieve better agreement with results of laboratory measurements in the sub-THz range. We demonstrate that our new model is in good agreement with modern versions of atmospheric propagation models. However, the atmospheric brightness temperature calculated using our new model systematically deviates from the results obtained with its empirical version. The deviation amounts up to several Kelvins in the microwindows between resonant water lines.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"333 ","pages":"Article 109319"},"PeriodicalIF":2.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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