The impact of aerosols on polarized sky radiance: model development, validation, and applications

Emde, Claudia; Buras, R.; Mayer, Bernhard; Blumthaler, M.

doi:10.5194/acp-10-383-2010

Cited by 136 publications

(69 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is required, for example, for closure experiments (consistency checks between different measurement methods involving an aerosol model, e.g., Wiegner et al, 2009;Gasteiger et al, 2011b;Müller et al, 2012;Bell et al, 2013;Ma et al, 2014;Zieger et al, 2014;Düsing et al, 2018), radiative transfer studies (e.g., Otto et al, 2009;Emde et al, 2010), the inversion of remote-sensing measurements (e.g., Dubovik et al, 2006;Gasteiger et al, 2011a;Müller et al, 2016), the inversion of in situ data (e.g., Weinzierl et al, 2009;Szymanski et al, 2009;Kassianov et al, 2014), aerosol layer visibility simulations (e.g., Weinzierl et al, 2012), dynamic aerosol transport models (e.g., Heinold et al, 2007;Balzarini et al, 2015), aerosol characterization (e.g., Gasteiger et al, 2017;Che et al, 2018;Zhuang et al, 2018), and solar energy (e.g., Polo et al, 2016;Kosmopoulos et al, 2017).…”

Section: Applicationsmentioning

confidence: 99%

MOPSMAP v1.0: a versatile tool for the modeling of aerosol optical properties

Gasteiger

Wiegner²

2018

Geosci. Model Dev.

View full text Add to dashboard Cite

Abstract. The spatiotemporal distribution and characterization of aerosol particles are usually determined by remotesensing and optical in situ measurements. These measurements are indirect with respect to microphysical properties, and thus inversion techniques are required to determine the aerosol microphysics. Scattering theory provides the link between microphysical and optical properties; it is not only needed for such inversions but also for radiative budget calculations and climate modeling. However, optical modeling can be very time-consuming, in particular if nonspherical particles or complex ensembles are involved.In this paper we present the MOPSMAP package (Modeled optical properties of ensembles of aerosol particles), which is computationally fast for optical modeling even in the case of complex aerosols. The package consists of a data set of pre-calculated optical properties of single aerosol particles, a Fortran program to calculate the properties of userdefined aerosol ensembles, and a user-friendly web interface for online calculations. Spheres, spheroids, and a small set of irregular particle shapes are considered over a wide range of sizes and refractive indices. MOPSMAP provides the fundamental optical properties assuming random particle orientation, including the scattering matrix for the selected wavelengths. Moreover, the output includes tables of frequently used properties such as the single-scattering albedo, the asymmetry parameter, or the lidar ratio. To demonstrate the wide range of possible MOPSMAP applications, a selection of examples is presented, e.g., dealing with hygroscopic growth, mixtures of absorbing and non-absorbing particles, the relevance of the size equivalence in the case of nonspherical particles, and the variability in volcanic ash microphysics.The web interface is designed to be intuitive for expert and nonexpert users. To support users a large set of default settings is available, e.g., several wavelength-dependent refractive indices, climatologically representative size distributions, and a parameterization of hygroscopic growth. Calculations are possible for single wavelengths or user-defined sets (e.g., of specific remote-sensing application). For expert users more options for the microphysics are available. Plots for immediate visualization of the results are shown. The complete output can be downloaded for further applications. All input parameters and results are stored in the user's personal folder so that calculations can easily be reproduced. The web interface is provided at https://mopsmap.net (last access: 9 July 2018) and the Fortran program including the data set is freely available for offline calculations, e.g., when large numbers of different runs for sensitivity studies are to be made.

show abstract

Section: Applicationsmentioning

confidence: 99%

MOPSMAP v1.0: a versatile tool for the modeling of aerosol optical properties

Gasteiger

Wiegner²

2018

Geosci. Model Dev.

View full text Add to dashboard Cite

show abstract

“…Although Rayleigh scattering is known to cause high polarization of sky radiance, multiple scattering, and aerosol scattering tend to lower the polarization. Emde et al (2010) found that the maximal sky polarization decreases to ∼15% for an atmosphere containing water soluble aerosol and to ∼12% for an atmosphere containing sea salt aerosol. Since both of these aerosol types are prevalent in the area of Rosh HaNikra (e.g., Bardouki et al, 2003), we can assume that such aerosol contribute to the relatively low maximal sky polarization observed in the current study.…”

Section: Two-dimensional Maps Of Dolp and Aolpmentioning

confidence: 99%

“…However, the intensity of light reflected off of the ocean is lower than the intensity of light propagating from the sky into the cave. Furthermore, as mentioned above, the presence of marine aerosols may cause a decrease in sky polarization (Emde et al, 2010). Therefore, the proximity of the cave to the ocean may or may not produce a net increase in polarization within the cave.…”

Section: Mean Dolp and Aolp For Each Section Of The Imagementioning

confidence: 99%

Linear Polarization Characteristics Within the Rosh HaNikra Mid-Littoral Cave, Israel

et al. 2018

View full text Add to dashboard Cite

Light polarization characteristics, i. e., degree of linear polarization (DoLP) and angle of linear polarization (AoLP), were documented in the depth of the littoral cave system of Rosh HaNikra on the northern Mediterranean shore of Israel (33 • 5 ′ 35.24 ′′ N, 35 • 6 ′ 17.16 ′′ E), based on light intensity sampled through polarizing filters at different hours of the day on different days of the year. This is the first study to investigate the state of light polarization in such a unique habitat in which photosynthetic organisms, such as cyanobacteria, microalgae, and macroalgae thrive. Such organisms play an essential ecological role as the energy base for the cave's fauna. Using these two methods, we found unique winter polarization characteristics within the cave, including high values of DoLP in the morning and at noon, reaching 50%, and nearly constant AoLP throughout the day. Given the low levels of light intensity that typically exist within the cave in the winter months, the relatively high DoLP and the nearly constant AoLP throughout the day may play a significant role in improving the ability of photosynthetic organisms within the cave to harvest light by orienting their light-harvesting receptors with respect to the AoLP. Using the polarization photograph analysis method, we were able to determine the polarization characteristics originating from the sky, reflection off of (including refraction into followed by refraction out of) the far sea surface, and reflection off of the cave wall separately. The maximum DoLP values originating from the sky, far ocean, and cave walls were found to be 27, 50, and 35%, respectively. The lowest daily variation in AoLP was that of light reflecting off the cave walls. The present study lays the foundation for any subsequent study of the role of light polarization in the distribution of the algal flora on the cave walls in and out of the water in the Rosh HaNikra cave and in sea caves in general.

show abstract

“…BMC algorithms generally treat the sampling of propagation directions by omitting the radiation's polarisation state and correcting subsequently for the bias introduced (Collins et al 1972 and works thereafter; e.g. Emde et al 2010;Gay et al 2010;Oikarinen 2001). As shown below, that approach may fail to render accurate solutions in conditions for which the scattering directions of the photons are strongly influenced by their polarisation states.…”

Section: The Bmc Algorithmmentioning

confidence: 99%

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

Muñoz

Mills

2014

A&A

View full text Add to dashboard Cite

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.

show abstract

The impact of aerosols on polarized sky radiance: model development, validation, and applications

Cited by 136 publications

References 37 publications

MOPSMAP v1.0: a versatile tool for the modeling of aerosol optical properties

MOPSMAP v1.0: a versatile tool for the modeling of aerosol optical properties

Linear Polarization Characteristics Within the Rosh HaNikra Mid-Littoral Cave, Israel

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

Contact Info

Product

Resources

About