International Research Fellowship Program: Analysis of Mexico City Air Pollution Using Nitrogen and Sulfur Dioxide Column Density Measurements From UV/visible Spectroscopy

国际研究奖学金计划使美国科学家和工程师能够在国外进行9至24个月的研究。该项目的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持梅根·L·梅拉米德博士与墨西哥国家自治大学的米歇尔·格鲁特博士在墨西哥墨西哥城为期24个月的研究奖学金。超大城市(人口超过1000万的城市)在当地、地区和全球空气污染中发挥着关键作用。最令人感兴趣的一个特大城市是墨西哥城，它是世界第三大城市，面积1500平方公里，估计人口约2000万。墨西哥城位于热带地区，海拔2240米，位于一个三面环山的平坦盆地中。墨西哥城的主要污染源是交通、发电和工业过程。墨西哥城人口密度高、地理环境独特、排放源多，导致高污染事件时有发生。两种主要的污染物是二氧化硫和二氧化氮，它们参与了形成酸雨、对流层臭氧和颗粒物的大气过程。这项研究对大墨西哥城盆地地区两个研究地点的二氧化硫和二氧化氮的紫外(UV)/可见光光谱测量结果进行了分析和解释。其中一个研究地点位于墨西哥城盆地的墨西哥国家自治大学(UNAM)。第二个研究点是Altzomoni，它位于墨西哥城盆地东南部，海拔约2000米，高于UNAM研究点。对这两个研究地点的二氧化硫和二氧化氮测量结果的分析和解释提供了有关污染流向墨西哥城盆地和流向墨西哥城盆地的重要信息，以及墨西哥城空气污染羽流的边界层动态。除了在UNAM和Altzomoni的固定研究地点外，正在使用一个流动研究平台来测量墨西哥城盆地点源的二氧化硫和二氧化氮的排放通量。固定式和移动式研究平台的测量结果正被应用于化学迁移模型，以便更好地模拟城市污染物在区域和全球范围内的迁移和转化。二氧化硫和二氧化氮的测量有助于理解特大城市污染对地方、区域和全球水平的影响。

0653087MelamedThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Megan L. Melamed to work with Dr. Michel Grutter at Universidad Nacional Autonoma de Mexico in Mexico City, Mexico.Megacities (cities with a population greater than 10 million) play a critical role in local, regional, and global air pollution. One megacity of primary interest is Mexico City, the third largest city in the world with an estimated population of ~20 million within an area of 1,500 square kilometers. Mexico City is located in the tropics at 2,240 meters above sea level in a flat basin surrounded by mountains on three sides. The primary sources of pollution in Mexico City are transportation, electricity generation, and industrial processes. The high-density population, the unique geographical setting, and multiple emission sources lead to high pollution episodes on a regular basis in Mexico City. Two pollutants of primary concern are sulfur dioxide and nitrogen dioxide, which are involved in atmospheric processes that form acid rain, tropospheric ozone, and particles. This research addresses the analysis and interpretation of ultraviolet (UV)/visible spectroscopy measurements of sulfur dioxide and nitrogen dioxide from two research sites in the greater Mexico City basin area. One research site is located in the Mexico City basin at La Universidad Nacional Autonoma de Mexico (UNAM). The second research site is Altzomoni, which is located to the southeast of the Mexico City basin at ~2,000 meters in altitude above the UNAM research site. Analysis and interpretation of the sulfur dioxide and nitrogen dioxide measurements from these two research sites is providing important information in regards to the outflow and in flow of pollution to the Mexico City basin and to the boundary layer dynamics of the Mexico City air pollution plume. In addition to the stationary research sites at UNAM and Altzomoni, a mobile research platform is being used to measure emission fluxes of sulfur dioxide and nitrogen dioxide from point sources in the Mexico City basin. The measurements from the stationary and mobile research platforms are being applied to chemical transport models in order to better simulate the transport and transformation of urban pollutants on regional and global scales. The sulfur dioxide and nitrogen dioxide measurements are contributing to the understanding of the impacts of pollution from a megacity on a local, regional, and global level.