Effects of Extra-Tropical Fires on Trace Gases and Aerosols

本项目将调查自1997年以来北方火灾排放对对流层中微量气体和气溶胶的影响。近年来的北方大火对大气中一氧化碳和气溶胶的丰度造成了很大的扰动，对氮氧化物和臭氧也有影响。一个大气化学和输送的三维模型（GEOS-Chem）将被用来分析这些火灾在半球尺度上的影响。模式模拟将由同化的气象场驱动，以考虑运输的年际变化。这项工作将采用两个独立导出的月度气体和气溶胶物种排放清单，用于北方火灾。在量化北方火灾排放的影响时，一个关键的不确定性是缺乏对排放物注入大气的高度的了解。来自Terra航天器上的多角度成像光谱仪（MISR）的数据将被分析，以确定自2000年以来西伯利亚大火排放的喷射高度，并将高度与燃烧面积、燃料消耗和当时的气象联系起来。将利用来自地面站和遥感的气体测量来评估模式模拟，包括一氧化碳的对流层污染测量（MOPITT）数据和气溶胶的中分辨率成像光谱辐射计（MODIS）数据。有关火灾区域、燃料装载和排放因素的数据将用于协调自下而上的火灾排放估计与三维模型计算结果和大气观测结果所施加的限制。气溶胶分布（黑碳和有机碳）和由此产生的气溶胶光学深度将用于计算极端火灾年与低火灾年的瞬时辐射强迫。了解这些火灾排放的影响是确定自然过程在导致美国和其他地方空气质量恶化和影响气候方面所起作用的必要条件。本项目将资助一名博士后。这项研究的参与者将通过参加专业会议和与其他学科的同事互动，专注于这项工作的更广泛的影响。

This project will investigate the impacts of boreal fire emissions since 1997 on trace gases and aerosols in the troposphere. Large boreal fires in recent years caused large perturbations to the atmospheric abundance of carbon monoxide and aerosols, with effects on nitrogen oxides and ozone as well. A three-dimensional model of atmospheric chemistry and transport (GEOS-Chem) will be used to analyze the hemispheric-scale impacts of these fires. Model simulations will be driven by assimilated meteorological fields to allow for interannual variability in transport. This work will employ two independently derived monthly emissions inventories of gas and aerosol species for boreal fires. A key uncertainty in quantifying the effects of boreal fire emissions is lack of knowledge of the heights at which the emissions are injected into the atmosphere. Data from the Multi-angle Imaging SpectroRadiometer (MISR) on board the Terra spacecraft will be analyzed to determine the injection heights of emissions from Siberian fires since 2000, and to relate the heights to area burned, fuel consumed, and prevailing meteorology. The model simulations will be evaluated with measurements of gases from surface stations, and from remote sensing, including Measurements of Pollution In The Troposphere (MOPITT) data for carbon monoxide (CO) and moderate resolution imaging spectroradiometer (MODIS) data for aerosols. Data for the areas of fires, fuel loading, and emission factors will be used to reconcile bottom-up estimates of fire emissions with constraints imposed by the results of the 3-d model calculations and atmospheric observations. The aerosol distributions (black carbon and organic carbon) and resulting aerosol optical depths from the boreal fires will be used to calculate the instantaneous radiative forcing for extreme fires years compared to low fire years. Understanding the impacts of emissions from these fires is required to determine the role that natural processes play in causing degradation of air quality in the United States and elsewhere, and in influencing climate.This project will support a post-doctoral student. Participants in this research will be focusing on the broader implications of this work by participating in professional meetings and though interactions with colleagues from other disciplines.