Development of an ecophysiology module in the GEOS-Chem chemical transport model version 12.2.0 to represent biosphere–atmosphere fluxes relevant for ozone air quality
Development of an ecophysiology module in the GEOS-Chem chemical transport model version 12.2.0 to represent biosphere–atmosphere fluxes relevant for ozone air quality
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DOI：
10.5194/gmd-16-2323-2023
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发表时间：
2023-05
影响因子：
5.1
通讯作者：
Joey C. Y. Lam;A. Tai;J. Ducker;C. Holmes
中科院分区：
文献类型：
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作者：
Joey C. Y. Lam;A. Tai;J. Ducker;C. Holmes
抽象的。地面臭氧（O3）是一种主要的空气污染物，对人类健康和生态系统生产力产生不利影响。植物气孔吸收对流层O3的去除反过来会对植物组织造成损害，对生态系统和作物健康产生影响。在许多大气和陆地表面模型中，气孔开放的功能由体积气孔导度表示，其通常是半经验参数化的，并且高度拟合历史观测。缺乏机械联系的生态生理过程，如光合作用，可能使模型不足以代表植物介导的反应，大气化学的长期变化，二氧化碳，气候和短暂的空气污染物浓度。因此，开发了一个新的生态生理学模块，以机械地模拟地球观测系统-化学模型中重要气体种类的陆地-大气交换，地球观测系统-化学模型是一个广泛用于大气化学研究的化学传输模型。该实施不仅允许干沉积与植物生理生态相结合，而且还使植物和作物的生产力和功能能够动态地响应大气化学变化。我们进行模拟，以评估生态生理学模块对模拟干沉积速度和浓度的表面O3对观测衍生的数据集称为SynFlux的影响。我们估计的气孔导度和O3干沉降速度接近SynFlux，在不同植物功能类型（PFT）中的均方根误差（RMSE）低于0.3 cm s-1，尽管表面O3浓度总体上存在正偏差（高达16 ppbv）。代表生态生理学被发现，以减少模拟偏差的沉积通量从先前的模型，但恶化的正偏差模拟O3浓度。正浓度偏差的增加主要归因于基于生态生理学的气孔导度一般较小（和更接近SynFlux值）比先前的半经验公式估计，要求进一步改善非气孔沉积和非沉积过程相关的O3模拟。使用GEOS-Chem估算的全球O3沉降通量为864 Tg O3 yr−1，新模块将这一估算值降低了92 Tg O3 yr−1。在没有O3损害的情况下，估计全球初级生产总值（GPP）为119 Pg C yr−1。O3引起的GPP减少为4.2 Pg C yr−1（3.5%）。CO2浓度升高（580 ppm）的情景产生更高的全球GPP（+16.8%）和更低的全球O3沉积汇（-3.3%）。基于光合作用的方案模拟的全球异戊二烯排放量为317.9 Tg C yr−1，比使用MEGAN（天然气和气溶胶排放模型）排放算法计算的排放量少31.2 Tg C yr−1（-8.9%）。这种新的模式发展动态地代表了植被和空气污染物之间的双向相互作用，从而提供了一个独特的能力，在评估植被介导的过程和反馈，可以塑造大气化学和空气质量，以及污染物对植被健康的影响，特别是对于任何时间尺度短于几十年的时间尺度。
Abstract. Ground-level ozone (O3) is a major air pollutant that adversely affects human health and ecosystem productivity. Removal of tropospheric O3 by plant stomatal uptake can in turn cause damage to plant tissues with ramifications for ecosystem and crop health. In many atmospheric and land surface models, the functionality of stomata opening is represented by a bulk stomatal conductance, which is often semi-empirically parameterized and highly fitted to historical observations. A lack of mechanistic linkage to ecophysiological processes such as photosynthesis may render models inadequate to represent plant-mediated responses of atmospheric chemistry to long-term changes in CO2, climate, and short-lived air pollutant concentrations. A new ecophysiology module was thus developed to mechanistically simulate land−atmosphere exchange of important gas species in GEOS-Chem, a chemical transport model widely used in atmospheric chemistry studies. The implementation not only allows for dry deposition to be coupled with plant ecophysiology but also enables plant and crop productivity and functions to respond dynamically to atmospheric chemical changes. We conduct simulations to evaluate the effects of the ecophysiology module on simulated dry deposition velocity and concentration of surface O3 against an observation-derived dataset known as SynFlux. Our estimated stomatal conductance and dry deposition velocity of O3 are close to SynFlux with root-mean-squared errors (RMSEs) below 0.3 cm s−1 across different plant functional types (PFTs), despite an overall positive bias in surface O3 concentration (by up to 16 ppbv). Representing ecophysiology was found to reduce the simulated biases in deposition fluxes from the prior model but worsen the positive biases in simulated O3 concentrations. The increase in positive concentration biases is mostly attributable to the ecophysiology-based stomatal conductance being generally smaller (and closer to SynFlux values) than that estimated by the prior semi-empirical formulation, calling for further improvements in non-stomatal depositional and non-depositional processes relevant for O3 simulations. The estimated global O3 deposition flux is 864 Tg O3 yr−1 with GEOS-Chem, and the new module decreases this estimate by 92 Tg O3 yr−1. Estimated global gross primary production (GPP) without O3 damage is 119 Pg C yr−1. O3-induced reduction in GPP is 4.2 Pg C yr−1 (3.5 %). An elevated CO2 scenario (580 ppm) yields higher global GPP (+16.8 %) and lower global O3 depositional sink (−3.3 %). Global isoprene emission simulated with a photosynthesis-based scheme is 317.9 Tg C yr−1, which is 31.2 Tg C yr−1 (−8.9 %) less than that calculated using the MEGAN (Model of Emissions of Gases and Aerosols from Nature) emission algorithm. This new model development dynamically represents the two-way interactions between vegetation and air pollutants and thus provides a unique capability in evaluating vegetation-mediated processes and feedbacks that can shape atmospheric chemistry and air quality, as well as pollutant impacts on vegetation health, especially for any timescales shorter than the multidecadal timescale.