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Simultaneous transmission/absorption photometry of particle-laden filters from wildland fires during the Biomass Burning Observation Project (BBOP) field campaign
Journal of Aerosol Science ( IF 4.5 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.jaerosci.2020.105614
Cary Presser , Ashot Nazarian , Duli Chand , Joseph M. Conny , Arthur Sedlacek , John M. Hubbe

Transmissivity and absorptivity measurements were carried out simultaneously in the visible (wavelength of 532 nm) at laboratory conditions using particle-laden filters obtained from a three-wavelength particle/soot absorption photometer (PSAP). The particles were collected on filters from wildland fires over the Pacific Northwest during the Department of Energy Biomass Burning Observation Project (BBOP) field campaign in 2013. The objective of this investigation was to apply this measurement approach, referred to as simultaneous transmission/absorption photometry (STAP), to estimate the aerosol extinction coefficient from actual field-campaign filter aerosol, and compare results with the PSAP. The STAP approach offers several advantages over the PSAP, including estimation of the extinction coefficient from temperature measurements (avoiding the complexities associated with filter reflectivity/scattering measurements), as well as determination of the filter optical properties and filter effects on particle absorption (resulting in particle absorption enhancement). The experimental arrangement included a laser probe beam impinging normal to the particle-coated surface of a vertically mounted filter, and a thermocouple placed flush in the middle of (and in thermal contact with) the filter uncoated back surface. With this simple arrangement, the transmissivity and absorptivity were determined simultaneously at a given laser beam wavelength. The measurement repeatability was better than 0.3 K (95 % confidence level) for temperature and 0.4 mW for laser power. The limit of detection for the extinction coefficient was estimated to be (8 to 12) Mm-1 (95 % confidence level) at about 1.9 mW laser power. The extinction coefficient was determined through measurement of both PSAP blank and exposed filters. Filters were obtained from nine different aircraft flights conducted during the BBOP campaign, representing different flight patterns, days, stages of burning, landscapes, and wildland fires. The STAP extinction coefficient matched the darkness of the filter coating, however the PSAP-filter results did not follow the same order. Although there were differences in transmissivity between the two techniques, the estimated values for absorption coefficient were in good agreement.

中文翻译:

生物质燃烧观测项目 (BBOP) 野外活动期间来自野地火灾的含颗粒过滤器的同时传输/吸收光度测量

在实验室条件下,使用从三波长粒子/烟尘吸收光度计 (PSAP) 获得的载有粒子的过滤器,在可见光(波长为 532 nm)中同时进行透射率和吸收率测量。在 2013 年能源部生物质燃烧观测项目 (BBOP) 现场活动期间,从太平洋西北部的野火中收集到的颗粒过滤器。本次调查的目的是应用这种测量方法,称为同步透射/吸收光度法(STAP),从实际的野战过滤气溶胶估计气溶胶消光系数,并将结果与​​ PSAP 进行比较。与 PSAP 相比,STAP 方法有几个优点,包括根据温度测量估计消光系数(避免与过滤器反射率/散射测量相关的复杂性),以及确定过滤器光学特性和过滤器对粒子吸收的影响(导致粒子吸收增强)。实验装置包括垂直于垂直安装的过滤器的颗粒涂层表面入射的激光探测光束,以及齐平放置在过滤器未涂层背面中间(并与之热接触)的热电偶。通过这种简单的布置,可以在给定的激光束波长下同时测定透射率和吸收率。温度测量重复性优于 0.3 K(95% 置信水平),激光功率优于 0.4 mW。在大约 1.9 mW 的激光功率下,消光系数的检测限估计为(8 到 12)Mm-1(95% 置信水平)。消光系数是通过测量 PSAP 空白和暴露的过滤器来确定的。过滤器是从 BBOP 活动期间进行的九次不同飞机飞行中获得的,代表不同的飞行模式、天数、燃烧阶段、景观和野火。STAP 消光系数与过滤器涂层的暗度相匹配,但是 PSAP 过滤器结果不遵循相同的顺序。尽管两种技术之间的透射率存在差异,但吸收系数的估计值非常一致。消光系数是通过测量 PSAP 空白和暴露的过滤器来确定的。过滤器是从 BBOP 活动期间进行的九次不同飞机飞行中获得的,代表不同的飞行模式、天数、燃烧阶段、景观和野火。STAP 消光系数与过滤器涂层的暗度相匹配,但是 PSAP 过滤器的结果并不遵循相同的顺序。尽管两种技术之间的透射率存在差异,但吸收系数的估计值非常一致。消光系数是通过测量 PSAP 空白和暴露的过滤器来确定的。过滤器是从 BBOP 活动期间进行的九次不同飞机飞行中获得的,代表不同的飞行模式、天数、燃烧阶段、景观和野火。STAP 消光系数与过滤器涂层的暗度相匹配,但是 PSAP 过滤器结果不遵循相同的顺序。尽管两种技术之间的透射率存在差异,但吸收系数的估计值非常一致。STAP 消光系数与过滤器涂层的暗度相匹配,但是 PSAP 过滤器结果不遵循相同的顺序。尽管两种技术之间的透射率存在差异,但吸收系数的估计值非常一致。STAP 消光系数与过滤器涂层的暗度相匹配,但是 PSAP 过滤器结果不遵循相同的顺序。尽管两种技术之间的透射率存在差异,但吸收系数的估计值非常一致。
更新日期:2020-12-01
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