Linearized vector radiative transfer model MCC++ for a spherical atmosphere

Postylyakov, O. V.

doi:10.1016/j.jqsrt.2004.01.009

Cited by 55 publications

(26 citation statements)

References 28 publications

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“…Thus, MC algorithms are often used as standards in the validation of other methods, particularly in cases that involve complex viewing and/or illumination geometries (Loughman et al 2004;Postylyakov 2004).…”

Section: The Bmc Algorithmmentioning

confidence: 99%

Pre-conditioned backward Monte Carlo solutions to radiative transport in planetary atmospheres

Muñoz

Mills

2014

A&A

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Context. The interpretation of polarised radiation emerging from a planetary atmosphere must rely on solutions to the vector radiative transport equation (VRTE). Monte Carlo integration of the VRTE is a valuable approach for its flexible treatment of complex viewing and/or illumination geometries, and it can intuitively incorporate elaborate physics. Aims. We present a novel pre-conditioned backward Monte Carlo (PBMC) algorithm for solving the VRTE and apply it to planetary atmospheres irradiated from above. As classical BMC methods, our PBMC algorithm builds the solution by simulating the photon trajectories from the detector towards the radiation source, i.e. in the reverse order of the actual photon displacements. Methods. We show that the neglect of polarisation in the sampling of photon propagation directions in classical BMC algorithms leads to unstable and biased solutions for conservative, optically-thick, strongly polarising media such as Rayleigh atmospheres. The numerical difficulty is avoided by pre-conditioning the scattering matrix with information from the scattering matrices of prior (in the BMC integration order) photon collisions. Pre-conditioning introduces a sense of history in the photon polarisation states through the simulated trajectories. Results. The PBMC algorithm is robust, and its accuracy is extensively demonstrated via comparisons with examples drawn from the literature for scattering in diverse media. Since the convergence rate for MC integration is independent of the integral's dimension, the scheme is a valuable option for estimating the disk-integrated signal of stellar radiation reflected from planets. Such a tool is relevant in the prospective investigation of exoplanetary phase curves. We lay out two frameworks for disk integration and, as an application, explore the impact of atmospheric stratification on planetary phase curves for large star-planet-observer phase angles. By construction, backward integration provides a better control than forward integration over the planet region contributing to the solution, and this presents a clear advantage when estimating the disk-integrated signal at moderate and large phase angles.

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Section: The Bmc Algorithmmentioning

confidence: 99%

Pre-conditioned backward Monte Carlo solutions to radiative transport in planetary atmospheres

Muñoz

Mills

2014

A&A

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“…The largest advantage of Monte Carlo models in limb geometry is that they properly take into account Earth´s sphericity both for single and multiple scattering (Oikarinen et al, 1999;Loughman et al, 2004). Furthermore they also provide the possibility to simulate an inhomogeneous atmosphere up to a high degree.…”

Section: Radiative Transfer Model "Tracy-ii"mentioning

confidence: 99%

Accounting for the effect of horizontal gradients in limb measurements of scattered sunlight

et al. 2008

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Abstract. Limb measurements provided by the SCanning Imaging Absorption spectrometer for Atmospheric CHartographY (SCIAMACHY) on the ENVISAT satellite allow retrieving stratospheric profiles of various trace gases on a global scale, among them BrO for the first time. For limb observations in the UV/VIS spectral region the instrument measures scattered light with a complex distribution of light paths: the light is measured at different tangent heights and can be scattered or absorbed in the atmosphere or reflected by the ground. By means of spectroscopy and radiative transfer modelling these measurements can be inverted to retrieve the vertical distribution of stratospheric trace gases.The fully spherical 3-D Monte Carlo radiative transfer model "Tracy-II" is applied in this study. The Monte Carlo method benefits from conceptual simplicity and allows realizing the concept of full spherical geometry of the atmosphere and also its 3-D properties, which is important for a realistic description of the limb geometry. Furthermore it allows accounting for horizontal gradients in the distribution of trace gases.In this study the effect of horizontally inhomogeneous distributions of trace gases along flight/viewing direction on the retrieval of profiles is investigated. We introduce a tomographic method to correct for this effect by combining consecutive limb scanning sequences and utilizing the overlap in their measurement sensitivity regions. It is found that if horizontal inhomogenity is not properly accounted for, typical errors of 20% for NO 2 and up to 50% for OClO around the altitude of the profile peak can arise for measurements close to the Arctic polar vortex boundary in boreal winter.

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“…(1), depends on the scattering angle Θ and the particle size, which for a spherical particle is described by the size parameter x 2πr∕λ, where r is the particle radius. Researchers in atmospheric remote sensing have reported that a scalar theory of light scattering is not sufficient to obtain accurate radiative transfer calculations [31,32]. When polarization effects are ignored, errors are introduced in the calculations of planetary phase functions, and the errors increase with the total scattering angle, defined as the angle between the incident starlight and the observer [33].…”

Section: Introductionmentioning

confidence: 99%

Stokes scattering matrix for human skin

et al. 2012

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We use a layered model of normal human skin based on size distributions of polydisperse spherical particles and their complex refractive indices to compute the Stokes scattering matrix at wavelengths in the visible spectral band. The elements of the Stokes scattering matrix are required in a polarized radiative transfer code for a coupled air-tissue system to compute the polarized reflectance and examine how it is dependent on the vertical structure of the inherent optical properties of skin, including the phase matrix. Thus, the elements of the Stokes scattering matrix can be useful for investigating polarization-dependent light propagation in turbid optical media, such as human skin tissue.

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Linearized vector radiative transfer model MCC++ for a spherical atmosphere

Cited by 55 publications

References 28 publications

Pre-conditioned backward Monte Carlo solutions to radiative transport in planetary atmospheres

Pre-conditioned backward Monte Carlo solutions to radiative transport in planetary atmospheres

Accounting for the effect of horizontal gradients in limb measurements of scattered sunlight

Stokes scattering matrix for human skin

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