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

通过观察火能排放来量化热对流注入高度，并评估对正演和反演建模的影响

• 批准号: NE/E01819X/1
• 负责人: Martin Wooster
• 金额: $ 22.17万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FE01819X%2F1
• 关键词: Quantifying; pyro; convective; injection; heights

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.

生物质燃烧是地球系统的主要动力，与之相关的野火释放出大量由一氧化碳等微量气体和黑碳等微粒组成的烟雾。对于某些物种来说，生物质燃烧的总排放量是最大的单一排放源之一，但单个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是高度可变的。一般认为，卫星地球观测数据的使用对于提供了解这些高度变化的排放源所必需的时间覆盖和空间采样至关重要。一旦升到高空，气流就会将这些烟雾输送到空中，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（飞机排放除外）不同的是，火灾可能会将烟羽喷射到对流层的不同高度，有时甚至会由于燃烧燃料产生的强烈热量和对流而进入平流层。某些热带火灾的残余排放物已在15公里高度观测到，加拿大个别林分火灾的烟柱也可接近这一高度。CTMs需要估计喷射高度，以便正确规定BB羽流与全球大气之间的相互作用，但目前关于该参数的信息非常少，因为关于燃烧区域和活跃火灾“热点”探测的“标准”卫星eo数据提供的相关信息很少。正因为如此，CTM运行通常假设所有BB排放都在一个固定的高度，通常假设所有污染物仅包含在对流层下层或甚至行星边界层中。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羽所覆盖，但由于缺乏卫星数据和更好地参数化实际喷射高度的方法，该主题受到的关注远远少于对排放源本身的大小和可变性的估计。然而，最近的一些关键研究已经确定了错误规定的排放喷射高度对CTMs正确表示排放运输和命运的能力的非常严重的影响。类似的问题造成了目前未知程度的误差，将影响基于观测到的大气中BB物种浓度的反演的“自上而下”排放估计。实验表明，正是火灾释放的能量驱动了对流上升气流，导致了烟雾排放的增加。因此，对火灾释放能量的新卫星观测提供了一个极好的机会，可以开发一个可测试的热原注入高度模型，该模型可以用来补充目前的BB数据集关于排放源强度和位置的数据，同时也可以导出注入高度信息，并用于CTM运行和反演研究。因此，本提案的目的是开发和测试一种使用卫星EO的方法，以极大地改进当前羽流喷射高度的处方。羽流喷射高度是模拟CTMs中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微量气体相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。与注入高度和烟雾成分垂直分布相关的新模型将是本研究的关键成果，同时还将获得一个注入高度“气候学”数据库，该数据库描述了注入高度升高的频率及其在BB影响区域的时空变化。

项目成果

Quantifying pyroconvective injection heights using observations of fire energy: sensitivity of spaceborne observations of carbon monoxide

• DOI: 10.5194/acp-15-4339-2015
• 发表时间: 2015-01-01
• 期刊: ATMOSPHERIC CHEMISTRY AND PHYSICS
• 影响因子: 6.3
• 作者: Gonzi, S.;Palmer, P. I.;Deeter, M. N.
• 通讯作者: Deeter, M. N.