DOI: 10.1002/2013JD020433
论文题名: Linking the IR transmittance to size and type of volcanic ash particles
作者: Scollo S. ; Baratta G.A. ; Palumbo M.E. ; Corradini S. ; Leto G. ; Strazzulla G.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 21 起始页码: 12207
结束页码: 12215
语种: 英语
英文关键词: Etna
; IR transmittance
; volcanic ash
Scopus关键词: Aspect ratio
; Finite difference method
; Fourier transform infrared spectroscopy
; Particle size
; Refractive index
; Remote sensing
; Etna
; Fourier transform infrared spectrometer
; IR transmittance
; Quantitative estimation
; Radiative transfer model
; Transmission spectrums
; Visible spectral range
; Volcanic ash
; Volcanoes
; atmospheric pollution
; FTIR spectroscopy
; infrared radiation
; optical depth
; particle size
; refractive index
; transmittance
; volcanic ash
; volcanic eruption
; Catania [Sicily]
; Etna
; Italy
; Sicily
英文摘要: In this work, we applied infrared spectroscopy to investigate the spectral signature of the volcanic ash particles emitted during the 21-24 July 2001 eruption at Mount Etna, in Italy. We used a Bruker Equinox-55 Fourier transform infrared spectrometer in the range 7000-600 cm-1 (1.43-16.67 μm) and, for every collected spectrum, an image of the volcanic ash particles was recorded in the visible spectral range through the same microscope. These images were then analyzed by standard image analysis software in order to evaluate the main features of the particle: the length of the major and minor axes (Max and Min L), Feret diameter (FD), equivalent diameter (ED), and aspect ratio (AR). We measured transmission spectra in different conditions; spectra of one single particle (Single-Particle Measurement, SPM), spectra of a number of particles from two to ten (Multi-Particle Measurements type 1, MPM1) and of more than a hundred particles (Multi-Particle Measurements type 2, MPM2). For SPM, Max and Min L range between 5 and 24 μm and 3.5 and 15 μm, FD ranges between 5.5 and 25 μm, ED varies between 5 and 19 μm, and AR between 0.45 and 0.95. For MPM1 and MPM2, the mean values of Max and Min L are between 4-17 μm and 3-10 μm, FD and ED between 5 and 19 μm and 3.5 and 23 μm, and AR between 0.3 and 1. The optical depth spectra as a function of the wave number clearly show the presence of the Christiansen effect that produces high transmission at a given frequency in the infrared region (Christiansen frequency). We find that the effect depends on the particle size through a linear relation. Both the Christiansen effect and their relationship with the ash particle effective radius were compared with radiative transfer model simulations using different ash refractive indexes. The combined use of the linear relationship and the spectral position of the Christiansen frequency also indicated the possibility to characterize ash type. All these information can be used to improve the IR remote sensing volcanic ash quantitative estimations. Key Points Infrared spectroscopy to investigate the spectral signature of volcanic ash The optical depth spectra show the presence of the Christiansen effect This work improves the IR remote sensing volcanic ash quantitative estimation ©2013. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/63177
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, sezione di Catania, Italy; Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Catania, Catania, Italy; Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy
Recommended Citation:
Scollo S.,Baratta G.A.,Palumbo M.E.,et al. Linking the IR transmittance to size and type of volcanic ash particles[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(21)