Journal ArticleDOI
Aerosol light absorption and its measurement: A review
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TLDR
In this paper, the authors used Mie theory for spherical particles and with more complicated numerical methods for other particle shapes to calculate aerosol light absorption in the atmosphere, which contributes to solar radiative forcing through absorption of solar radiation and heating of the absorbing aerosol layer.Abstract:
Light absorption by aerosols contributes to solar radiative forcing through absorption of solar radiation and heating of the absorbing aerosol layer. Besides the direct radiative effect, the heating can evaporate clouds and change the atmospheric dynamics. Aerosol light absorption in the atmosphere is dominated by black carbon (BC) with additional, significant contributions from the still poorly understood brown carbon and from mineral dust. Sources of these absorbing aerosols include biomass burning and other combustion processes and dust entrainment. For particles much smaller than the wavelength of incident light, absorption is proportional to the particle volume and mass. Absorption can be calculated with Mie theory for spherical particles and with more complicated numerical methods for other particle shapes. The quantitative measurement of aerosol light absorption is still a challenge. Simple, commonly used filter measurements are prone to measurement artifacts due to particle concentration and modification of particle and filter morphology upon particle deposition, optical interaction of deposited particles and filter medium, and poor angular integration of light scattered by deposited particles. In situ methods measure particle absorption with the particles in their natural suspended state and therefore are not prone to effects related to particle deposition and concentration on filters. Photoacoustic and refractive index-based measurements rely on the heating of particles during light absorption, which, for power-modulated light sources, causes an acoustic signal and modulation of the refractive index in the air surrounding the particles that can be quantified with a microphone and an interferometer, respectively. These methods may suffer from some interference due to light-induced particle evaporation. Laser-induced incandescence also monitors particle heating upon absorption, but heats absorbing particles to much higher temperatures to quantify BC mass from the thermal radiation emitted by the heated particles. Extinction-minus-scattering techniques have limited sensitivity for measuring aerosol light absorption unless the very long absorption paths of cavity ring-down techniques are used. Systematic errors can be dominated by truncation errors in the scattering measurement for large particles or by subtraction errors for high single scattering albedo particles. Remote sensing techniques are essential for global monitoring of aerosol light absorption. While local column-integrated measurements of aerosol light absorption with sun and sky radiometers are routinely done, global satellite measurements are so far largely limited to determining a semi-quantitative UV absorption index.read more
Citations
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Journal ArticleDOI
Bounding the role of black carbon in the climate system: A scientific assessment
Tami C. Bond,Sarah J. Doherty,David W. Fahey,Piers M. Forster,Terje Koren Berntsen,Benjamin DeAngelo,Mark Flanner,Steven J. Ghan,Bernd Kärcher,Dorothy Koch,Stefan Kinne,Yutaka Kondo,Patricia K. Quinn,Marcus C. Sarofim,Martin G. Schultz,Michael Schulz,Chandra Venkataraman,Hua Zhang,Shiqiu Zhang,Nicolas Bellouin,Sarath K. Guttikunda,Philip K. Hopke,Mark Z. Jacobson,Johannes W. Kaiser,Zbigniew Klimont,Ulrike Lohmann,Joshua P. Schwarz,Drew Shindell,Trude Storelvmo,Stephen G. Warren,Charles S. Zender +30 more
TL;DR: In this paper, the authors provided an assessment of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice.
Journal ArticleDOI
Chemistry of atmospheric brown carbon.
TL;DR: Understanding of the climate-related properties of atmospheric OC is still incomplete and the specific ways in which OC impacts atmospheric environment and climate forcing are just beginning to be understood.
Journal ArticleDOI
Recommendations for reporting "black carbon" measurements
Andreas Petzold,John A. Ogren,Markus Fiebig,P. Laj,Shao-Meng Li,Urs Baltensperger,Thomas Holzer-Popp,Stefan Kinne,Gelsomina Pappalardo,Nobuo Sugimoto,Christoph Wehrli,Alfred Wiedensohler,Xiaoye Zhang +12 more
TL;DR: In this article, the authors present a recommended terminology to clarify the terms used for black carbon in atmospheric research, with the goal of establishing unambiguous links between terms, targeted material properties and associated measurement techniques.
Light Scattering by a Spheroidal Particle
G. Yamamoto,S. Asano +1 more
TL;DR: The solution of electromagnetic scattering by a homogeneous prolate (or oblate) spheroidal particle with an arbitrary size and refractive index is obtained for any angle of incidence by solving Maxwell's equations under given boundary conditions.
Journal Article
Light scattering by particles: Computational methods
TL;DR: This book presents the separation-of-variables and T-matrix methods of calculating the scattering of electromagnetic waves by particles, and the connection between the theory and the computer programs is reinforced by references in thecomputer programs to equations in the text.
References
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Book
Absorption and Scattering of Light by Small Particles
TL;DR: In this paper, a Potpourri of Particles is used to describe surface modes in small Particles and the Angular Dependence of Scattering is shown to be a function of the size of the particles.
Book
Computational Electrodynamics: The Finite-Difference Time-Domain Method
TL;DR: This paper presents background history of space-grid time-domain techniques for Maxwell's equations scaling to very large problem sizes defense applications dual-use electromagnetics technology, and the proposed three-dimensional Yee algorithm for solving these equations.
Atmospheric chemistry and physics: from air pollution to climate change.
TL;DR: In this article, the authors present a model for the chemistry of the Troposphere of the atmosphere and describe the properties of the Atmospheric Aqueous phase of single aerosol particles.
Book
Atmospheric Chemistry and Physics: From Air Pollution to Climate Change
TL;DR: In this paper, the authors present a model for the chemistry of the Troposphere of the atmosphere and describe the properties of the Atmospheric Aqueous phase of single aerosol particles.
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