Ice Crystal Scavenging of C1 - C4 Alcohols and Ethylene Glycol

9314358雪晶(结冰)对过冷云滴的Snider捕获和(从水蒸气中的)沉积生长是导致冰晶大小足以作为降水从中纬度对流层云中移除的机制。在雾化过程中，云滴溶解的污染物气体被并入新生的降水颗粒中。在这一过程中气体清除的效率已经在实验室和现场实验中进行了研究。在遥远的大陆山顶地点(怀俄明州东南部的麋鹿山天文台)的自然云中进行的涉及亲水化学物种的实验被提出，以提供关于通过气相沉积生长的冰晶中微量气体被并入的程度的具体信息。我们的实验策略是在饱和水的空气中生长附着在通风基质上的冰晶，空气经过预调节以去除过冷的云滴，并通过添加已知数量的每种研究化合物(甲醇、乙醇或正丁醇)。我们打算测量，作为气相浓度的函数，研究化合物在样品冰晶中的含量。由此得到的数据集将提供对亲水性和取代基链长度如何影响气体清除的检查。除了这些研究外，还将对这些常量醇在由浮选形成的冰中保留的程度进行检查。选择进行研究的化合物是有意义的，因为它们与冬季羟基自由基浓度反应的寿命通常与在降水中去除的估计寿命相当。因此，重要的是要表征冰相水流变仪对醇以及其他亲水性化合物的去除效率。此外，选定的在大气中起重要作用的化合物。除了这些研究外，我们计划同时进行xxx醇和无机物质xxxxxxxxx的气相测量，使用无机气体作为受人为污染空气污染的示踪剂，研究与低分子量醇相对应的生物和人为来源过程的相对重要性。

9314358 Snider Capture of supercooled cloud droplets by snow crystals (riming) and depostion growth (from the vapor are the mechanisms which lead to ice crystal sizes sufficient for removal as precipitation from mid-latitude tropospheric clouds. During ricing, cloud-droplet-dissolved pollutant gases are incorporated into nascent precipitation particles. The efficiency of gas scavenging during this process has been studied in both laboratory and field experiments.conducted in natural clouds at a remote continental mountain-top site (Elk Mountain Observatory in southeastern Wyoming) and involving hydrophilic chemical species are proposed to provide specific information about the extent to which trace gases are incorporated into ice crystals growing by vapor deposition. Our experimental strategy is to grow ice crystals attached to a ventilated substrate in water-saturated air that is pre- conditioned to remove supercooled cloud droplets and by addition of known amounts of each study compound (either methanol, ethanol, or normal butanol). We intend to measur, as a function of concentrations in the gas-phase, the amount of study compound incorporated into the sampled ice crystal. The resulting data set will afford an examination of how both hydrophilic properties and substituent chain length affect gas scavenging. These studies will be complimented by an examination of the extent to which ambient amounts of these normal alcohols are retained in ice formed by ricing. The compounds selected for study are of interest because their lifetimes with respect to reaction with wintertime concentrations of hydroxyl radical are generally comparable to estimated lifetimes corresponding to removal in precipitation. Therefore, it is important to characterize the efficiency of removal for alcohols, as well as other hydrophilic compounds, by ice-phase hydrometeors. In addition, the selected compounds that play important roles in the atmosphere. In addition to these studies, we plan to conduct concurrent gas-phase measurements of the xxx alcohols and the inorganic species xxxxxxxxxx Using the inorganic gases as tracers of air contaminated by man-made pollution, the relative importance of biogenic and anthropogenic source processes corresponding to the low-molecular weight alcohols will be examined.