Anomalous Selective Absorption of Smoke Aerosol during Forest Fires in Alaska in July–August 2019

IF 0.9 4区地球科学 Q4 METEOROLOGY & ATMOSPHERIC SCIENCES Izvestiya Atmospheric and Oceanic Physics Pub Date : 2023-12-25 DOI:10.1134/s000143382306004x

G. I. Gorchakov, V. M. Kopeikin, R. A. Gushchin, A. V. Karpov, E. G. Semoutnikova, O. I. Datsenko, T. Ya. Ponomareva

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Abstract

According to the monitoring data of the optical and microphysical characteristics of smoke aerosol at AERONET stations during forest fires in the summer of 2019 in Alaska, the anomalous selective absorption of smoke aerosol has been detected in the visible and near-infrared spectral range from 440 to 1020 nm. With anomalous selective absorption, the imaginary part of the refractive index of smoke aerosol reached 0.315 at a wavelength of 1020 nm. A power-law approximation of the spectral dependence of the imaginary part of the refractive index with an exponent from 0.26 to 2.35 is proposed. It is shown that, for anomalous selective absorption, power-law approximations of the spectral dependences of the aerosol optical extinction and absorption depths are applicable with an Ångström exponent from 0.96 to 1.65 for the aerosol optical extinction depth and from 0.97 to –0.89 for the aerosol optical absorption depth, which reached 0.72. Single scattering albedo varied from 0.62 to 0.96. In the size distribution of smoke aerosol particles with anomalous selective absorption, the fine fraction of particles of condensation origin dominated. The similarity of the fraction of particles distinguished by anomalous selective absorption with the fraction of tar balls (TBs) detected by electron microscopy in smoke aerosol, which, apparently, arise during the condensation of terpenes and their oxygen-containing derivatives, is noted.

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2019 年 7-8 月阿拉斯加森林火灾期间烟雾气溶胶的异常选择性吸收

摘要根据2019年夏季阿拉斯加森林火灾期间AERONET站烟雾气溶胶光学和微物理特征监测数据，在440～1020 nm可见光和近红外光谱范围内检测到烟雾气溶胶的异常选择性吸收。在异常选择性吸收的作用下，烟雾气溶胶折射率的虚部在波长为 1020 nm 时达到 0.315。提出了折射率虚部随光谱变化的幂律近似值，其指数为 0.26 至 2.35。研究表明，对于异常选择性吸收，气溶胶光学消光和吸收深度的光谱依赖性的幂律近似值是适用的，气溶胶光学消光深度的 Ångström 指数从 0.96 到 1.65，气溶胶光学吸收深度的 Ångström 指数从 0.97 到 -0.89，达到 0.72。单散射反照率在 0.62 至 0.96 之间变化。在具有异常选择性吸收的烟雾气溶胶粒子的粒径分布中，凝结源粒子的细小部分占主导地位。通过电子显微镜在烟雾气溶胶中检测到的焦油球（TBs）显然是在萜烯及其含氧衍生物的凝结过程中产生的。

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来源期刊

Izvestiya Atmospheric and Oceanic Physics 地学-海洋学

CiteScore

1.40

自引率

28.60%

发文量

审稿时长

6-12 weeks

期刊介绍： Izvestiya, Atmospheric and Oceanic Physics is a journal that publishes original scientific research and review articles on vital issues in the physics of the Earth’s atmosphere and hydrosphere and climate theory. The journal presents results of recent studies of physical processes in the atmosphere and ocean that control climate, weather, and their changes. These studies have possible practical applications. The journal also gives room to the discussion of results obtained in theoretical and experimental studies in various fields of oceanic and atmospheric physics, such as the dynamics of gas and water media, interaction of the atmosphere with the ocean and land surfaces, turbulence theory, heat balance and radiation processes, remote sensing and optics of both media, natural and man-induced climate changes, and the state of the atmosphere and ocean. The journal publishes papers on research techniques used in both media, current scientific information on domestic and foreign events in the physics of the atmosphere and ocean.