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。化学模型将被用来分析最近的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冬季运输、排放和反应(冬季)调查活动，在2015年2月至3月期间进行。这项研究的三个目标是：(1)改善冬季污染物排放的限制；(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。将使用GEOS-Chem化学输送模式来解释冬季实地活动的观测结果。由于畜牧业和肥料田的氨(NH3)排放是高度不确定的，该项目包括检验模型中不同的NH3排放清单捕捉美国上空观测到的冬季氨(NH4+)和NH4+湿沉降通量的能力。一级和二级有机气溶胶前体排放将受到限制，以改善有机气溶胶在模式中的代表性。冬季将利用地面和飞机对甲醛和二氧化氯的观测来调查它们的来源。最后，该模型将与地面观测一起使用，以进一步了解整个美国地面PM2.5组成对排放变化的季节性敏感性。该项目将支持一名博士后学者和一名研究生。这一奖项反映了NSF的法定使命，并通过使用基金会的学术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.