RAPID: A New Technique for Vertical Profiling of Volatile Organic Compounds Within and Above the Convective Boundary Layer

RAPID：对流边界层内外挥发性有机化合物垂直分析的新技术

• 批准号: 1133418
• 负责人: Daniel Knopf
• 金额: $ 6.55万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1133418&HistoricalAwards=false
• 关键词: RAPID; New; Technique; Vertical; Profiling

The dominating role of volatile organic compounds (VOCs) on the chemistry and oxidation potential within a forest canopy is well known. However, without knowing the concentration vertical profiles of VOCs, one cannot calculate their flux with much precision. Vertical profiles extending above the canopy height are usually determined by sampling from balloons but because of limitations inherent to balloon platforms, samples can only be taken at one or two different altitudes, it takes many minutes to collect a sample at each altitude, and balloon profiles rarely are able to get near the top of the convective boundary layer (CBL), thus only a partial profile is usually observable. This RAPID project will develop in time for initial deployment during the BEACHON (Biosphere-atmosphere Exchange of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen) intensive sampling campaign in summer 2011 a technique to collect vertical profiles of VOCs within the CBL and overlying lower free troposphere from a small research aircraft. The technique, called "frozen sampling", is simple in principle; a relatively long tube of air is installed within a light aircraft. During a rapid climb, sample air flows through the tubing. Upon reaching the upper point of the vertical profile, the sample is trapped or "frozen" within the tubing by closing off both ends, using valves. Within a very short period of time (on the order of one minute) a vertical profile is trapped within the sample tubing, and stored until the sample can be analyzed on the ground.The "frozen sampling" technique will be useful to many ground-based field campaigns, where low level, high resolution vertical profiles are desirable. In addition, two undergraduate students will be involved in determining the characteristics of the sampling system, using their knowledge of fluid dynamics, chemistry, and physics in a real world application. The students will also travel to Manitou Forest in Colorado and assist with the field component of the BEACHON campaign. At least one of the students will be recruited from the WISE (Women in Science and Engineering) Program at Stony Brook University.

挥发性有机化合物（VOCs）对森林冠层内化学和氧化电位的主导作用是众所周知的。然而，如果不知道挥发性有机物的浓度垂直分布，人们就不能精确地计算它们的通量。在树冠高度以上的垂直廓线通常通过气球采样来确定，但由于气球平台固有的限制，只能在一个或两个不同的高度上采集样本，在每个高度上采集样本需要几分钟，气球廓线很少能够接近对流边界层（CBL）的顶部，因此通常只能观察到部分廓线。该RAPID项目将在2011年夏季BEACHON（生物圈-大气能量、气溶胶、碳、H2O、有机氮交换）密集采样活动期间及时开发一种技术，以收集CBL内和覆盖低自由对流层的VOC垂直剖面。这项技术被称为“冷冻取样”，原理很简单;一个相对较长的空气管安装在一架轻型飞机上。在快速爬升过程中，样品空气流过管道。在到达垂直剖面的上点时，通过使用阀门封闭两端，将样品捕获或“冷冻”在管内。在很短的时间内（大约一分钟），垂直剖面被捕获在样品管中，并存储，直到样品可以在地面上进行分析。“冷冻取样”技术将有助于许多地面实地活动，其中低水平，高分辨率的垂直剖面是可取的。此外，两名本科生将参与确定采样系统的特性，在真实的世界应用中使用他们的流体动力学，化学和物理学知识。学生们还将前往科罗拉多的马尼图森林，协助海滩运动的实地工作。至少有一名学生将从斯托尼布鲁克大学的WISE（科学与工程领域的女性）项目中招募。