Quantifying pyro-convective injection heights via obervation of fire energy emissions, and assessing the impact on forward and inversion modelling

生物质燃烧是地球系统的主要动力，涉及的野火释放大量烟雾，由一氧化碳等微量气体和黑碳等颗粒组成。对于一些物种，生物质燃烧的总排放量是最大的单一排放源之一，但个别火灾的空间位置和物种排放的确切数量在空间和时间上都有很大的变化。卫星对地观测数据的使用通常被认为是提供了解这些高度可变排放源所需的时间复盖和空间采样的关键。一旦升空，气流就会将烟雾排放出去，影响它们的寿命、化学转化和命运。化学传输模型(CTMS)用于量化这些过程，但与所有其他排放物(飞机排放的除外)不同的是，由于燃烧燃料产生的强烈热量和对流，火灾可能会将其烟羽注入对流层的不同高度，有时甚至更低的平流层。在15公里的高度观察到了某些热带火灾的残留物，加拿大个别森林火灾的烟柱可以接近这样的高度。CTMS要求估计排放喷射高度，以便正确规定BB羽流与全球大气之间的相互作用，但目前关于这一参数的信息很少，因为关于燃烧区域和活跃火区探测的“标准”卫星-地球观测数据提供的相关信息很少。正因为如此，CTM的运行通常假设所有BB排放的高度都是固定的，通常假定所有污染物只包含在对流层下部，甚至可能是行星边界层。这显然是不现实的，因为可以看到许多野火被上升到许多公里高度的大型对流烟柱覆盖，但由于缺乏卫星数据和方法来更好地参数化实际喷射高度，这个问题受到的关注远远少于对排放源本身的规模和可变性的估计。然而，最近的一些关键研究确定了不正确地规定排放喷射高度对CTMS正确反映排放、运输和去向的能力的非常严重的影响。类似的问题，造成了目前未知的误差程度，将影响根据观测到的大气中BB类物质浓度的反演而进行的“自上而下”的排放估计。实验表明，是火灾释放的能量驱动了对流上升气流，导致了烟尘排放的升高。因此，对火灾释放的能量的新的卫星观测提供了一个极好的机会来开发一个可测试的火源喷射高度模型，该模型可用于补充目前关于排放源强度和位置的BB数据集，方法是还可以推导出关于喷射高度的信息，并将其用于CTM运行和反演研究。因此，这项提议的目的是制定和测试一种利用卫星地球观测的方法，以极大地改进目前关于羽流喷射高度的规定，而羽流喷射高度是在CTMS中模拟生物质燃烧排放所必需的一个强制性领域，并且在反演与BB痕量气体有关的化学和运输以推断排放源的大小和可变性时是必要的。一个关于喷射高度和烟雾成分垂直分布的新模型将是这项研究的一个关键成果，同时还有一个喷射高度“气候学”数据库，该数据库描述了喷射高度升高的频率及其在受BB影响地区的时空变化。

Biomass burning is a major dynamic of the Earth system, and the wildfires involved emit copious quantities of smoke made up of trace gases such as carbon monoxide and particulates such as black carbon. For some species, the total emissions from biomass burning represent amongst the largest single emissions source, but the spatial location of the individual fires and the exact amounts of species emitted are highly variable in both space and time. Use of satellite Earth Observation (EO) data are generally considered to be critical in providing the temporal coverage and spatial sampling necessary for an understanding of these highly variable emissions sources. Once aloft, air currents transport the smoke emissions, affecting their longevity, chemical conversion and fate. Chemical transport models (CTMs) are used to quantify these processes, but unlike all other emissions (except those from aircraft) fires may inject their smoke plumes into various heights in the troposphere and occasionally even lower stratosphere by virtue of the intense heat and convection produced by the burning fuel. Emissions remnants from certain tropical fires have been observed at 15 km altitude, and smoke plumes of individual Canadian stand-replacing forest fires can approach such heights. CTMs require an estimate of emissions injection height in order to correctly prescribe the interaction between the BB plumes and the global atmosphere, but at present there is very little information on this parameter since the 'standard' satellite-EO data on burned area and active fire 'hotspot' detections provides little relevant information. Because of this, CTM runs often assume a single fixed altitude for all BB emissions, usually presuming that all pollutants are contained solely within the lower troposphere or perhaps even the planetary boundary layer. This is clearly unrealistic since many wildfires can be seen capped by a large convective smoke plume rising to many km altitude, but because of a lack of satellite data and methods with which to better parameterise the actual injection height the topic has received far less attention than has estimation of the magnitude and variability of the emissions sources themselves. However, a number of recent key studies have determined the very serious implications that incorrectly prescribed emissions injection heights have for the ability of CTMs to correctly represent emissions transport and fate. Similar problems, causing a currently unknown degree of error, will affect 'top-down' emission estimates based on the inversion of observed atmospheric concentrations of BB species. Experiments have indicated that it is the energy released by a fire that drives the convective updraft responsible for the elevated injection of the smoke emissions. New satellite observations of the energy released by fires therefore offer an excellent opportunity to develop a testable model for pyrogenic injection heights that can be used to supplement current BB datasets on emissions source strength and location, by allowing information on injection altitude to also be derived and used in CTM runs and inversion studies. The aim of this proposal is therefore to develop and test a methodology for using satellite EO to greatly improve the current prescriptions of plume injection heights that are a mandatory field required to model biomass burning emissions in CTMs, and are necessary when inverting the chemistry and transport associated with BB trace gases to infer the magnitude and variability of emissions sources. A new model relating injection height and the vertical distribution of smoke constituents will be a key output from this research, along with a injection height 'climatology' database describing the frequency of elevated injections heights and their spatio-temporal variation across BB affected regions.