Aerosol optical properties at Pasadena, CA during CalNex 2010

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• 作者：Jonathan E. Thompson^a ; ^{jon.thompson@ttu.edu} ; Patrick L. Hayes^b ; Jose L. Jimenez^b ; Kouji Adachi^c ; ¹ ; Xiaolu Zhang^d ; Jiumeng Liu^d ; Rodney J. Weber^d ; Peter R. Buseck^c
• 关键词：Aerosol optics ; Single scatter albedo ; Scattering coefficient ; Extinction coefficient ; Absorption coefficient ; Mass absorption cross section ; Mass scatter efficiency ; Direct climate forcing ; CalNex ; Albedometer ; Brown carbon ; WSOC ; Absorption enhancement
• 刊名：Atmospheric Environment
• 出版年：2012
• 期刊代码：11_13522310
• 类别：env
• 出版时间：August, 2012
• 卷：55
• 期：Complete
• 页码：190-200
• 文件大小：1464 K

摘要

Aerosol optical properties measured at the Pasadena, CA site during the CalNex field campaign in May-June 2010 are summarized. Average measurements of PM_2.5 aerosol extinction, scattering, absorption coefficients, and single scattering albedo (b_ext, b_scat, b_abs and SSA) at 位聽=聽532聽nm were 62聽Mm^鈭?, 58聽Mm^鈭?, 4聽Mm^鈭?, and 0.92, respectively. The aerosol optical densities were 5 times lower than during the SCAQS study in 1987, highlighting major progress in PM control in the Los Angeles area in the last two decades. The period May 30-June 8 2010 was characterized by exceptionally high aerosol loading (b_ext up to 250聽Mm^鈭?). During this period, b_ext, b_scat, and SSA tended to peak during the mid-morning. Correlation of PM_2.5 b_ext, b_scat with mass concentration data yielded mass scattering and mass extinction coefficients of 3.5-5.1聽m²聽g^鈭? for 532聽nm. Aerosol b_abs were compared directly to mass concentration of elemental carbon (EC) yielding a campaign average mass absorption cross section (M.A.C.) of 5.7聽卤聽1.8聽m²聽g^鈭?. TEM analysis of particles suggests soot was often internally mixed or adhering to sulfate and/or organics. Total non-refractory PM₁ mass was a good quantitative indicator of coated soot fraction. Alteration of M.A.C. with mixing/coating state was not detected, however, increases in M.A.C. were linked to the presence of light absorbing, water-soluble organic carbon (WSOC) suggesting a possible role of this material invisible light absorption in the LA basin.