Studies of the Impact of Emission of Reactive Gases from Arctic Snowpacks and Sea Ice

该项目的动机是两个环境观测：1）在过去的几十年里，北极的积雪和海冰覆盖率一直在以惊人的速度减少，可能与气候变化有关，2）空气-雪的相互作用似乎对积雪覆盖环境中低层大气的组成有重大影响。 最近在北极的实地测量表明，阳光照射下的积雪会向大气中排放各种光解活性物质，如溴（Br 2）、氯化溴（BrCl）、氮氧化物（NOx）、亚硝酸（HONO）、甲醛（HCHO）和（CH 3CHO）。 这些物种对低层大气中臭氧（O3）的丰度有影响;在北极春季，低层大气（高达约1公里）中的所有O3都可以从与积雪/海冰表面发生的过程有关的卤素原子反应中去除。 臭氧可以在阳光照射下的积雪中被破坏，与卤素原子有关的化学反应导致气相元素汞转化为可能有毒的颗粒相汞，然后沉积在北冰洋表面。 卤素化学物质也可能影响北极霾的普遍性/严重性。 由于O3和颗粒对地球的辐射平衡有影响，O3有助于确定大气的氧化能力，而且由于积雪正在减少，因此预测大气的未来状态以及与北极的关系，需要对空气-雪相互作用的定量了解。 虽然人们知道，在光化学上重要的物种从阳光照射的积雪排放到低层大气中，但这些过程对大气的影响还没有得到很好的界定。 首席研究员将通过测量北极积雪和海冰上方排放的化学物质的垂直结构，制定解决这些问题的方法。 他将对分子卤素进行垂直剖面测量，这些分子卤素是它们在大气中的一些关键反应产物，即可能从北冰洋排放的有机卤素化合物，以及活性羰基化合物，特别是CH 3CHO。 对于卤化化合物，将通过测量从地面到几米高的垂直剖面来实现这些目标。 对于CH 3CHO，将开发使用装有仪表的电池供电小型飞艇进行从地面到约1公里的垂直剖面测量的能力。 该取样平台将提供从近地表至一公里范围内的任何地表（如开阔水域、海冰和铅）进行取样的灵活性。 他们将在2005年春季的一个月内，在阿拉斯加州的巴罗附近地区和当地北冰洋海面进行测量。更广泛的影响：虽然研究界对北极的环境和大气研究进行了有效的交流，但负责任地教育公众了解北极正在发生的变化也很重要。 首席研究员将涉及著名和成功的冒险家/作家，彼得·劳里，作为创建一系列多媒体产品的第一步，旨在教育学校儿童和成年人关于北极及其人民，在全球气候变化及其对北极的影响的背景下。 劳里先生将前往巴罗和采访研究人员和当地的因纽特爱斯基摩人，在准备生产的书籍和视频。 此外，研究生和本科生教育是这一努力的核心方面。

ABSTRACTShepsonOPP-0325361This project is motivated by two environmental observations: 1) snowpack and sea ice cover in the Arctic has been decreasing at alarming rates over the past couple decades, presumably related to climate change, and 2) air-snow interactions appear to have a significant impact on the composition of the lower atmosphere in snow covered environments. Recent field measurements in the Arctic have shown that sunlit snowpacks emit a variety of photolytically active species, such as bromine (Br2), bromine chloride (BrCl), nitrogen oxides (NOx), nitrous acid (HONO), formadehyde (HCHO), and (CH3CHO), into the atmosphere. These species have an impact on the abundance of ozone (O3) in the lower atmosphere; in the Arctic springtime, all the O3 in the lower atmosphere (up to ~ one km) can be removed from halogen atom reactions related to processes that occur at the snowpack/sea ice surface. Ozone can be destroyed within the sunlit snowpack, and that halogen-atom related chemistry results in the conversion of gas phase elemental mercury into potentially toxic particle phase mercury that then can be deposited on the Arctic Ocean surface. It is also likely that the halogen chemistry impacts the prevalence/severity of Arctic haze. Because O3 and particles have an impact on Earth's radiative balance, and O3 helps determine the oxidizing power of the atmosphere, and because snow cover is diminishing, prediction of the future state of the atmosphere, and how that relates to the Arctic, requires a quantitative understanding of air-snow interactions. Although it is known that photochemically important species are emitted from sunlit snowpacks into the lower atmosphere, the impacts of these processes on the atmosphere are not well defined. The Principal Investigator will develop methods to pursue these issues, through measurements of the vertical structure of the emitted chemical species above snowpacks and sea-ice in the Arctic. He will conduct vertical profile measurements of molecular halogens, some of their key atmospheric reaction products organohalogen compounds that may be emitted from the Arctic Ocean, and reactive carbonyl compounds, most specifically CH3CHO. For the halogenated compounds, these objectives will be pursued through measurements of vertical profiles from the surface to a few meters aloft. For CH3CHO, will develop the capability to conduct vertical profiles from the surface to ~1km, using an instrumented, battery powered small blimp. This sampling platform will provide the flexibility to sample from the near surface to one km, over any surface, such as open water, sea ice, and leads. They will conduct measurements during one month in the spring, 2005, in the area around Barrow, Alaska, and the local Arctic Ocean surface.Broader Impacts: Although the research community communicates effectively about environmental and atmospheric research in the Arctic, it is also important to responsibly educate the public about changes that are occurring in the Arctic. The Principal Investigator will involve the well-known and successful adventurer/author, Peter Lourie, as the first step to create a series of multimedia products aimed at educating school children and adults about the Arctic, and its people, in the context of global climate change and its impact on the Arctic. Mr. Lourie will travel to Barrow and interview researchers and the local Inupiat Eskimos, in preparation for production of books and videos. In addition, graduate and undergraduate education are central aspects of this effort.