Humidity‐dependent optical properties of fine particles during the Big Bend Regional Aerosol and Visibility Observational Study
Humidity‐dependent optical properties of fine particles during the Big Bend Regional Aerosol and Visibility Observational Study
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DOI：
10.1029/2002jd002998
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发表时间：
2003-05
影响因子：
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通讯作者：
W. Malm;D. Day;S. Kreidenweis;J. Collett;Taehyoung Lee
中科院分区：
文献类型：
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作者：
W. Malm;D. Day;S. Kreidenweis;J. Collett;Taehyoung Lee
[1]环境保护局(EPA)和国家公园管理局(NPS)发起了一项名为大弯区域气溶胶和能见度观测研究(BRAVO)的综合野外实验，以调查德克萨斯州大本德国家公园降低能见度的气溶胶的来源。这项研究从1999年7月的第一周开始，历时4个月。这项研究的目的之一是深入了解环境气溶胶的大气光散射特性，特别是当它们与其吸湿性有关时。本文将报告干散射和环境散射的测量和模型估计之间的比较，以及湿散射和干散射的测量和模型比f(RH)作为相对湿度(RH)的函数的比较。两个平衡模式，结合Mie散射理论，被用来预测大气气溶胶水分含量和相关的大气散射增加。模拟和测量的潮解点和结晶点也进行了比较。测量和模拟的潮解度始终在10%RH以内，而结晶相对湿度始终在几个百分点以内。分析表明，在大多数情况下，气溶胶在较低的相对湿度(20-30%)下会保留一些水分，而在大多数情况下，由于相对湿度的作用，只有无机盐的吸湿增长才能解释观测到的散射增加。
[1] The Environmental Protection Agency (EPA) and National Park Service (NPS) initiated a comprehensive field experiment called The Big Bend Regional Aerosol and Visibility Observational Study (BRAVO) to investigate the source of visibility-reducing aerosols at Big Bend National Park, Texas. The study was carried out over a period of 4 months starting in the first week of July 1999. One objective of the study was to gain insight into the atmospheric light-scattering properties of ambient aerosols, especially as they relate to their hygroscopicity. This paper will report on comparisons between measured and modeled estimations of dry and ambient scattering and comparisons between measured and modeled ratios of wet and dry scattering, f(RH), as a function of relative humidity (RH). Two equilibrium models, exercised in combination with Mie scattering theory, were used to predict atmospheric aerosol water content and associated increase in atmospheric scattering. Modeled and measured deliquescence and crystallization points were also compared. Measured and modeled deliquescence were always within 10% RH while crystallization RHs were always within a few percentage points. The analysis suggests that on most days some water is retained by the aerosol at low RHs (20–30%) and in most cases the hygroscopic growth of only inorganic salts accounted for all the observed increase in scattering as a function of RH.