Lightning HOx: Laboratory and Photochemical Modeling Studies of Hydroxyl (OH) and Hydroperoxyl (HO2) Generated by Atmospheric Electrical Activity

该项目的重点是实验室实验，以研究在闪电过程中形成的极具活性的化学物种，即自由基的生成。大气自由基是一种非常活泼的原子或原子基团，能够去除或改变大气中的许多污染物。这项研究的目的是了解闪电产生这些自由基的条件，以及它们如何影响全球和区域大气化学。大气自由基很重要，因为它们影响大气中污染物和温室气体的寿命。实验室在各种条件下产生的电火花和电晕将用于研究闪电产生的NOx(LNOx)和闪电产生的Hox(LHOx)。(A)火花强度、频率、长度、半径和数目；(B)电晕强度和空间范围；(C)发电点和化学传感器之间的时间；(D)作为所有这些因素的函数的HOx/NOx生成的比率；(E)HOx、NOx和O3的生成之间的关系；(F)HOx、NOx和O3的生成与火花和电晕特性的关系；(G)压力、水蒸气和OH反应性对这些关系的影响以及对计算的OH暴露量的影响；以及(H)通过挥发性有机化合物(VOC)的减少测量的OH暴露量。这些实验室测量将用光化学箱模型模拟，以确定初始的HOx/NOx比率和由此产生的OH暴露量，以便与测量值进行比较。来自这些实验室和模型研究的信息将被参数化，以包括在全球化学传输模型中，该模型将被用来理解LHOx对大气氧化的全球和区域影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project focuses on laboratory experiments to study the generation of extremely reactive chemical species, known as radicals, that are formed during lightning. An atmospheric radical is a very reactive atom or group of atoms that has the ability to remove or change many pollutants in the atmosphere. The goal of this research is to understand the conditions under which these radicals are produced by lightning and how they influence global and regional atmospheric chemistry. Atmospheric radicals are important because they affect the lifetimes of pollutants and greenhouse gases in the atmosphere.Laboratory generated electrical sparks and corona over a wide range of conditions will be used to study lightning-generated NOx (LNOx) and lightning-generated HOx (LHOx). The ratio LHOx/LNOx will be measured as will its dependence on: (a) spark intensity, frequency, length, radius, and number; (b) corona intensity and spatial extent; (c) time between generation point and the chemical sensors; (d) the ratio of HOx/NOx production as a function of all of these factors; (e) the relationships among the production of HOx, NOx, and O3; (f) the relationships of the production of HOx, NOx, and O3 to spark and corona characteristics; (g) the influence of pressure, water vapor, and OH reactivity on these relationships and on the calculated OH exposure; and (h) the OH exposure measured by decreases in a volatile organic compound (VOC).These laboratory measurements will be simulated with photochemical box models to determine the initial HOx/NOx ratio and the resulting OH exposure for comparison with measured values. The information from these laboratory and modeling studies will be parametrized for inclusion in a global chemical transport model, which will be used to understand the global and regional implications of LHOx on atmospheric oxidation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.