Isoprene emission potentials from European oak forests derived from canopy flux measurements: an assessment of uncertainties and inter-algorithm variability
Isoprene emission potentials from European oak forests derived from canopy flux measurements: an assessment of uncertainties and inter-algorithm variability
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来自冠层通量测量的欧洲橡树林的异戊二烯排放潜力：不确定性和算法间变异性的评估
DOI：
10.5194/bg-14-5571-2017
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发表时间：
2017
期刊：
影响因子：
4.9
通讯作者：
E. Nemitz
中科院分区：
文献类型：
--
作者：
B. Langford;J. Cash;W. Acton;A. Valach;C. N. Hewitt;S. Fares;I. Goded;C. Gruening;E. House;A. Kalogridis;V. Gros;Richard Schafers;Rick M. Thomas;M. Broadmeadow;E. Nemitz
抽象的。生物源排放算法预测，橡树林占欧洲异戊二烯预算总额的70%。然而，异戊二烯排放潜力（IEPs），支持这些模型的估计计算从一个非常有限的数量的叶级观测，因此是高度不确定的。微气象学技术，如涡度协方差，越来越多地用于直接测量整个冠层通量，从中可以计算异戊二烯排放潜力。在这里，我们回顾了五个观测数据集的异戊二烯通量从一系列的橡树林在英国，意大利和法国。我们概述的程序，以纠正所测得的净通量的沉积和化学通量发散的损失，这被发现是在5-8和4- 5%的顺序，分别。校正后的观测数据被用来推导异戊二烯排放潜力在每个网站在一个两步的过程。首先，6种常用的排放算法反演出异戊二烯排放潜力的时间序列，然后计算每个站点的平均异戊二烯排放潜力与相关的不确定性。我们使用这些数据来评估所得出的排放潜力如何根据所使用的特定排放算法而变化，重要的是，根据所采用的特定方法来得出平均场地特定排放潜力。我们的研究结果表明，异戊二烯排放潜力可以变化高达4的因素，这取决于所使用的具体算法，以及它是否用于大叶或冠层环境（CE）模型格式。当使用相同的算法时，发现计算的平均异戊二烯排放潜力变化多达34%，这取决于如何得出平均值。使用与自然界气体和气溶胶排放模型（MEGAN）2.1版一致的方法，我们推导出五个测量点的新生态系统尺度异戊二烯排放潜力：（10 500 ± 2500 µg m−2 h−1）; Bosco丰塔纳，意大利（1610 ± 420 µg m−2 h−1）; Castelporziano，意大利（121 ± 15 µg m−2 h−1）;意大利伊斯普拉（7590 ± 1070 µg m−2 h−1）;法国上普罗旺斯天文台（7990 ± 1010 µg m−2 h−1）。然后将生态系统规模的异戊二烯排放潜力外推到叶水平，并与之前的叶水平测量结果进行比较，这两个物种被认为占欧洲异戊二烯预算总额的50%。文献值与使用G93算法计算的发射电势非常一致，Q的发射电势分别为85 ± 75和78 ± 25 µg g−1 h−1。robur和Q.分别为毛。相比之下，使用G 06算法计算的排放潜力，与先前研究中用于推导欧洲预算的算法相同，显着较低，我们将其归因于过去光照和温度条件的影响。采用这些新的G 06比排放潜力Q。robur（55 ± 24 µg g−1 h−1）和Q.毛茛（47 ± 16 µg g-1 h-1）使欧洲预算预计减少0.17%。我们的研究结果表明，计算的异戊二烯排放潜力变化很大，这取决于在其计算中使用的具体方法。因此，我们建议社会现在采用一种标准化的方法来校正微气象通量测量，并用于推导异戊二烯和其他生物挥发性有机化合物的排放潜力。
Abstract. Biogenic emission algorithms predict that oak forests account for ∼ 70 % of the total European isoprene budget. Yet the isoprene emission potentials (IEPs) that underpin these model estimates are calculated from a very limited number of leaf-level observations and hence are highly uncertain. Increasingly, micrometeorological techniques such as eddy covariance are used to measure whole-canopy fluxes directly, from which isoprene emission potentials can be calculated. Here, we review five observational datasets of isoprene fluxes from a range of oak forests in the UK, Italy and France. We outline procedures to correct the measured net fluxes for losses from deposition and chemical flux divergence, which were found to be on the order of 5–8 and 4–5 %, respectively. The corrected observational data were used to derive isoprene emission potentials at each site in a two-step process. Firstly, six commonly used emission algorithms were inverted to back out time series of isoprene emission potential, and then an average isoprene emission potential was calculated for each site with an associated uncertainty. We used these data to assess how the derived emission potentials change depending upon the specific emission algorithm used and, importantly, on the particular approach adopted to derive an average site-specific emission potential. Our results show that isoprene emission potentials can vary by up to a factor of 4 depending on the specific algorithm used and whether or not it is used in a big-leaf or canopy environment (CE) model format. When using the same algorithm, the calculated average isoprene emission potential was found to vary by as much as 34 % depending on how the average was derived. Using a consistent approach with version 2.1 of the Model for Emissions of Gases and Aerosols from Nature (MEGAN), we derive new ecosystem-scale isoprene emission potentials for the five measurement sites: Alice Holt, UK (10 500 ± 2500 µg m−2 h−1); Bosco Fontana, Italy (1610 ± 420 µg m−2 h−1); Castelporziano, Italy (121 ± 15 µg m−2 h−1); Ispra, Italy (7590 ± 1070 µg m−2 h−1); and the Observatoire de Haute Provence, France (7990 ± 1010 µg m−2 h−1). Ecosystem-scale isoprene emission potentials were then extrapolated to the leaf-level and compared to previous leaf-level measurements for Quercus robur and Quercus pubescens, two species thought to account for 50 % of the total European isoprene budget. The literature values agreed closely with emission potentials calculated using the G93 algorithm, which were 85 ± 75 and 78 ± 25 µg g−1 h−1 for Q. robur and Q. pubescens, respectively. By contrast, emission potentials calculated using the G06 algorithm, the same algorithm used in a previous study to derive the European budget, were significantly lower, which we attribute to the influence of past light and temperature conditions. Adopting these new G06 specific emission potentials for Q. robur (55 ± 24 µg g−1 h−1) and Q. pubescens (47 ± 16 µg g−1 h−1) reduced the projected European budget by ∼ 17 %. Our findings demonstrate that calculated isoprene emission potentials vary considerably depending upon the specific approach used in their calculation. Therefore, it is our recommendation that the community now adopt a standardised approach to the way in which micrometeorological flux measurements are corrected and used to derive isoprene, and other biogenic volatile organic compounds, emission potentials.
影响因子：
18.3
作者：
C. Hewitt;K. Ashworth;A. Boynard;A. Guenther;B. Langford;A. Mackenzie;P. Misztal;E. Nemitz;S. Owen;M. Possell;T. Pugh;Annette C Ryan;O. Wild
通讯作者：
C. Hewitt;K. Ashworth;A. Boynard;A. Guenther;B. Langford;A. Mackenzie;P. Misztal;E. Nemitz;S. Owen;M. Possell;T. Pugh;Annette C Ryan;O. Wild
影响因子：
3.4
作者：
A. Vaughan;James D. Lee;M. Shaw;P. Misztal;S. Metzger;S. Metzger;M. Vieno;B. Davison;T. Karl;L. Carpenter;A. Lewis;R. Purvis;A. Goldstein;C. Hewitt
通讯作者：
A. Vaughan;James D. Lee;M. Shaw;P. Misztal;S. Metzger;S. Metzger;M. Vieno;B. Davison;T. Karl;L. Carpenter;A. Lewis;R. Purvis;A. Goldstein;C. Hewitt