Development of a Near-UV Aerosol Albedometer

众所周知，大气中的自然和人为颗粒物通过散射和吸收太阳辐射直接改变地球的辐射平衡。然而，气溶胶的直接辐射效应的确切程度仍然有些不确定。虽然对可见光和近红外气溶胶的表征技术的研究一直在进行中，但对近紫外线(UV)部分气溶胶的直接光学表征的关注较少。这项工作将侧重于开发一种仪器，以测量气溶胶散射系数、消光系数和相关的紫外线波长下的单次散射反照率。该仪器将利用研究人员以前开发的方法，在积分球内分散的同一气溶胶样品上同时测量气溶胶散射系数和消光系数。消光将使用“腔衰荡”技术进行测量，而散射测量将通过收集从探测光束与积分球散射的光来进行。三个步骤的项目计划是建造仪器，在实验室环境中优化和表征其性能，然后对气溶胶光学性质进行环境监测。这项研究的智力优势来自于开发关键测量设备，以帮助弥补目前在近紫外线气溶胶直接光学表征能力方面的主要差距。广泛的影响包括增加对与气候研究相关的气溶胶强迫的理解。将通过支持两名女研究生和几名本科生来强调教育和扩大参与方面。公众宣传活动将包括在校园内有许多参观者的时段(如周末体育赛事)举行实验室开放日，让普通公众有机会看到户外烹饪等人类活动如何改变大气成分。

It is well established that atmospheric particulates, both natural and anthropogenic, directly alter earth's radiative balance by scattering and absorbing solar radiation. The exact magnitude aerosol's direct radiative effect nonetheless remains somewhat uncertain. While research on techniques to characterize aerosols in the visible and near infrared has been ongoing, there has been less attention paid to direct optical characterization of aerosols in the near-ultraviolet (UV) part of the spectrum. This effort will focus on development of an instrument to measure the aerosol scattering coefficient, extinction coefficient, and associated single-scatter albedo at UV wavelengths. This instrument will make use of methodology previously developed by the researchers in which aerosol scattering and extinction coefficients are measured simultaneously on the same aerosol sample dispersed within an integrating sphere. Extinction will be measured using the "cavity ring-down" technique while scattering measurements would be made by collecting light scattered from the probe beam with the integrating sphere. The three-step project plan is to construct the instrument, optimize and characterize its performance in a laboratory setting, and then perform ambient monitoring of aerosol optical properties.The intellectual merit of the research comes through development of provision of key measurements to help to close a major gap in current ability for direct optical characterization of aerosols in the near UV.Broader impacts include increased understanding of aerosol forcing relevant to climate research. Educational and broadening participation aspects will be emphasized via support for two female graduate students and several undergraduates. Public outreach will include a laboratory open-house during periods with many visitors on campus (such as weekend sporting events) to allow the general public an opportunity to see how human activities such as outdoor cooking can alter atmospheric composition.