Isoprene emission response to drought and the impact on global atmospheric chemistry
Isoprene emission response to drought and the impact on global atmospheric chemistry
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DOI：
10.1016/j.atmosenv.2018.01.026
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发表时间：
2018-06-01
影响因子：
5
通讯作者：
Pallardy, Stephen
中科院分区：
文献类型：
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作者：
Jiang, Xiaoyan;Guenther, Alex;Pallardy, Stephen
生物异戊二烯排放在大气化学中起着非常重要的作用。这些排放在很大程度上取决于各种环境条件，如温度、太阳辐射、植物水分胁迫、环境臭氧和二氧化碳浓度以及土壤湿度。目前的生物排放模型（即，MEGAN）可以模拟排放对一些主要驱动变量的响应，例如温度和太阳辐射的短期变化，但其他因素要么缺失，要么表现不佳。在本文中，我们提出了一种新的建模方法，考虑了干旱胁迫对植物光合作用和异戊二烯排放的生理影响，用于MEGAN3生物排放模型。我们通过将该算法集成到现有的MEGAN2.1生物源排放模型框架中来测试MEGAN3方法，该框架嵌入到社区地球系统模型（CLM4.5/CESM1.2）的全球社区土地模型中。单点模拟进行比较，对现有的现场测量在密苏里州奥扎克AmeriFlux（MOFLUX）现场。模拟结果表明，MEGAN 3方法使用光合作用参数（V-cmax）和土壤湿度因子（beta（t））来确定干旱活动因子，从而更好地模拟了非干旱和干旱时期的异戊二烯排放量。采用MEGAN3方法进行的全球模拟预测，与使用没有任何干旱影响的默认CLM4.5/MEGAN2.1预测的值相比，全球异戊二烯年排放量减少17%。这种减少导致异戊二烯排放量减少的地区的地表臭氧和氧化剂发生变化。因此，在耦合地球系统模式中，准确模拟干旱引起的异戊二烯排放响应是十分重要的。
Biogenic isoprene emissions play a very important role in atmospheric chemistry. These emissions are strongly dependent on various environmental conditions, such as temperature, solar radiation, plant water stress, ambient ozone and CO2 concentrations, and soil moisture. Current biogenic emission models (i.e., Model of Emissions of Gases and Aerosols from Nature, MEGAN) can simulate emission responses to some of the major driving variables, such as short-term variations in temperature and solar radiation, but the other factors are either missing or poorly represented. In this paper, we propose a new modelling approach that considers the physiological effects of drought stress on plant photosynthesis and isoprene emissions for use in the MEGAN3 biogenic emission model. We test the MEGAN3 approach by integrating the algorithm into the existing MEGAN2.1 biogenic emission model framework embedded into the global Community Land Model of the Community Earth System Model (CLM4.5/CESM1.2). Single-point simulations are compared against available field measurements at the Missouri Ozarks AmeriFlux (MOFLUX) field site. The modelling results show that the MEGAN3 approach of using of a photosynthesis parameter (V-cmax) and soil wetness factor (beta(t))o determine the drought activity factor leads to better simulated isoprene emissions in non-drought and drought periods. The global simulation with the MEGAN3 approach predicts a 17% reduction in global annual isoprene emissions, in comparison to the value predicted using the default CLM4.5/MEGAN2.1 without any drought effect. This reduction leads to changes in surface ozone and oxidants in the areas where the reduction of isoprene emissions is observed. Based on the results presented in this study, we conclude that it is important to simulate the droughtin-duced response of biogenic isoprene emission accurately in the coupled Earth System model.