Tropospheric OH, HO2, NO2, and Total OH Chemical Loss Rates: Development, Measurements and Analysis

在这个项目中，测量对流层羟基和羟基自由基的仪器将在地面和NASA DC-8飞机上进行测试、改进和部署。该仪器是在美国国家科学基金会和美国国家航空航天局的支持下，经过几年的开发和现场测试，在低压检测室中基于激光诱导荧光的仪器。该仪器现在具有足够的灵敏度和特异性，可以测量整个对流层中的这些自由基。这项研究的主要目标是更好地了解从对流层表面到对流层上层的对流层氧化。另一个目标是了解在早期的现场作业中测量到的氢过氧自由基的低混合比。此外，还将在仪器中增加一条新的通道来测量羟基自由基的总化学损失率。该部分将由放电流动力学系统和羟基检测轴组成，该轴将接收来自仪器主要部分的一小部分紫外激光。总OH损失率测量的结果将与反应速率系数和测量的碳氢化合物的乘积的总和进行比较，以测试当前使用的化学模型和反应速率的准确性。仪器进口上的不同过滤器将允许不同种类的反应物。＊＊＊

9628059 Brune In this project, an instrument to measure tropospheric hydroxyl and hydroperoxyl radicals will be tested, improved, and deployed both on the ground and from the NASA DC-8 aircraft. This instrument , based on laser induced fluorescence in a detection chamber at low pressure, is the product of several years of development and field testing under NSF and NASA support. The instrument is now sensitive and specific enough for measurements of these radicals throughout the troposphere. The primary goal of this research is to better understand tropospheric oxidation from the surface to the upper troposphere. Another goal is to understand the low mixing ratios of hydroperoxyl radical measured in earlier field campaigns. In addition, a new channel will be developed and added to the instrument which will measure the total chemical loss rate of hydroxyl radical. This part will consist of a discharge flow kinetics system and a hydroxyl detection axis, which will receive a small portion of the UV laser light from the main part of the instrument. Results from this total OH loss rate measurement will be compared to the sum of the products of reaction rate coefficients and measured hydrocarbons to test the accuracy of currently used chemical models and reaction rates. Different filters on the instrument inlet will allow some speciation of the reactants. ***