Towards an Improved Understanding of Winter Air Pollution

这项研究旨在更好地了解美国冬季的空气污染情况。化学模型将用于分析最近一项实地研究的数据，该研究是由美国国家科学基金会资助的，于2015年2月至3月进行的运输、排放和反应性冬季调查（WINTER）活动。这项研究的结果将与改善空气质量的政策决定有关。本课题的三个研究目标是：(1)完善对冬季污染物排放的约束；(2)阐明冬季氧化剂的来源；(3)研究直径小于2.5微米的颗粒物（PM2.5）和臭氧浓度对过去和未来排放变化的季节性响应。GEOS-Chem化学输运模型将用于解释冬季野外活动的观测结果。由于来自畜牧业和施肥农田的氨（NH3）排放高度不确定，本项目包括对模型中不同NH3排放清单捕捉已观测到的美国冬季铵（NH4+）浓度和氨（NH4+）湿沉降通量的能力进行检查。一次和二次有机气溶胶前体排放将受到限制，以改善模型中有机气溶胶的表示。冬季对HCHO和ClNO2的地面和飞机观测将用于调查它们的来源。最后，将该模型与地面观测数据结合使用，进一步了解整个美国地表PM2.5组成对排放变化的季节性敏感性。该项目将资助一名博士后和一名研究生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This research is directed toward gaining a better understanding of wintertime air pollution in the United States. Chemical modeling will be used to analyze data from a recent field study, the NSF-funded Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign conducted during February and March of 2015. The results of this research will be relevant for policy decisions regarding improvements in air quality.The three research objectives of this project are to: (1) improve the constraints on wintertime pollutant emissions; (2) elucidate the origin of oxidants during winter; and (3) examine the seasonal response of particulate matter less than 2.5 microns in diameter (PM2.5) and ozone concentrations to past and future changes in emissions. The GEOS-Chem chemical transport model will be used to interpret the observations from the WINTER field campaign. Because emissions of ammonia (NH3) from livestock operations and fertilized fields are highly uncertain, this project includes an examination of the ability of different NH3 emissions inventories in the model to capture the observed winter concentrations of ammonium (NH4+) and NH4+ wet deposition fluxes over the US. Primary and secondary organic aerosol precursor emissions will be constrained in order to improve the representation of organic aerosol in the model. Wintertime ground-based and aircraft observations of HCHO and ClNO2 will be used to investigate their sources during winter. Finally, the model will be used together with surface observations to further understand the seasonal sensitivity of surface PM2.5 composition to emission changes over the entire US. This project will support a postdoctoral scholar and a graduate student.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.