Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS)

燃烧生物质(如灌木、草地、树木)在确定地球表面和大气的组成方面发挥着持续的作用，在一些地区，随后向大气排放的微量气体可与燃烧化石燃料的排放量相媲美。近40年来，科学界研究了不同类型生物质的微量气体排放量和相关的大气气体浓度，但我们的知识仍然不完整，反映了这一地球系统过程的异质性和随机性。地面和对流层化学的空间观测的出现使人们第一次得以一窥全球对流层燃烧的大范围性质和影响。这些数据仍然是扩大与燃烧排放或相关大气浓度有关的详细点或区域尺度测量的关键。然而，如果没有大气化学和传输的计算机模型以及现场测量，地球观测(EO)数据产品很难解释。在这项提案中，我们汇编了一个生物质燃烧测量和建模的综合方案，其中包括地面和飞机现场数据、对流层微量气体和颗粒的空间观测，以及大气化学计算机模型的继承(从详细的点模型到最先进的全球三维模型)。在这里，我们重点关注北部北部地区的生物质燃烧，飞机飞行任务对北美地区的生物质燃烧进行了采样。我们的研究重点是更好地了解源自生物质燃烧区域的气团内的大气化学。特别是，我们跟进和扩大了最近由NERC资助的北大西洋上空的飞机运动(臭氧和前体的洲际运输，ITOP)的令人惊讶的结果，该运动测量了北美边界层在穿越北大西洋向欧洲飞行时的外流并确定了其特征。在ITOP期间，飞机无意中对生物质燃烧流出的水进行了采样，发现分析这些数据的模型无法再现大量有机分子和氮物种的形态。作为这项提议的一部分，我们计划飞越北大西洋，专门对北美生物质燃烧的流出进行采样，并配备一套更合适的飞机仪器，这些仪器将有助于理解和解决这一在大气化学中无法解释的发现。由此产生的数据将由黄金标准的主化学机制进行分析，这是一个明确的模型，描述了相关大气化合物的降解。大气科学家通常面临的最大挑战之一是从详细的现场测量扩大到区域和更大的空间尺度。在这里，我们通过使用全球3-D大气化学和传输模型以及来自空间传感器的数据来应对这一挑战，方法是将该模型用作飞机数据和相对航向卫星数据之间的中介。通过使用详细的飞机数据(数据同化)对模式进行统计“调整”，我们可以更好地估计北美生物质燃烧的外流的大小和三维分布及其对北半球大气成分的影响。该提案将使我们更好地从根本上了解生物质燃烧过程中不断演变的大气化学，更好地了解如何将来自现场和星载传感器的数据结合起来，将详细的小尺度数据与更大的空间尺度联系起来，并更好地定量地了解北方森林火灾对北半球大气组成的影响。

The burning of biomass (e.g., shrubs, grasslands, trees) has an ongoing role in determining the composition of Earth's surface and atmosphere, and in some regions subsequent emissions of trace gases to the atmosphere rival those from fossil fuel burning. For nearly 40 years the scientific community has studied rates of emissions of trace gases from different types of biomass and associated amospheric gaseous concentrations but our knowledge remains incomplete, reflecting the heterogeneous and stochastic nature of this Earth System process. The advent of space-borne observations of land-surface and tropospheric chemistry provided the first glimpse of the large-scale nature and impact of burning in the global troposphere. These data remain key to scaling-up detailed point- or regional-scale measurements related to burning emissions or associated atmospheric concentrations. However, Earth Observation (EO) data products are difficult to interpret without the aid of computer models of atmospheric chemistry and transport and in situ measurements. In this proposal we have assembled an integrative programme of measurements and modelling of biomass burning that encompasses ground-based and aircraft in situ data, space-borne observations of tropospheric trace gases and particles, and a heirachy of computer models of atmospheric chemistry (detailed point models to state-of-the-art global 3-D models). Here, we focus on biomass burning over northern boreal regions, with the aircraft missions sampling outflow from North America. Our research focus is to better understand atmospheric chemistry within air masses originating from regions of biomass burning. In particular, we follow up and expand upon surprising results from a recent NERC-funded aircraft campaign (Intercontinental Transport of Ozone and Precursors, ITOP) over the North Atlantic that measured and characterised outflow from the North American boundary layer as it travelled over the North Atlantic towards Europe. During ITOP the aircraft unintentionally sampled outflow from biomass burning and found that models analysing those data were unable to reproduce the large concentrations of organic molecules and the speciation of nitrogen species. As part of this proposal we plan to fly over the North Atlantic specifically to sample outflow from North American biomass burning equipped with a more suitable suite of aircraft instruments that will help to understand and resolve this unexplained discovery in atmospheric chemistry. The resulting data will be analysed by the gold standard Master Chemical Mechanism, an explicit model description of the degradation of relevant atmospheric compounds. One of the biggest challenges that atmospheric scientists typically face is the scaling-up from detailed in situ measurements to regional and larger spatial scales. Here, we address this challenge by using global 3-D models of atmospheric chemistry and transport and data from space-borne sensors by using the model as an intermediary between the aircraft data and the relatively course satellire data. By statistically 'tuning' the model using the detailed aircraft data (data assimilation) we can better estimate the magnitude and 3-D distribution of outflow from North American biomass burning and its resulting effects on atmospheric composition over the northern hemisphere. The proposal will provide us with a better fundamental understanding of the evolving atmospheric chemistry within biomass burning, an improved understanding of how to combine data from in situ and space-borne sensors to relate detailed small-scale data to larger spatial scales, and a better quantitative understanding of the impact of boreal forest fires on the atmospheric composition of the northern hemisphere.