Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate.
Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate.
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DOI：
10.1002/2017gl073056
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发表时间：
2017-05-28
影响因子：
5.2
通讯作者：
Riipinen I
中科院分区：
文献类型：
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作者：
Rastak N;Pajunoja A;Acosta Navarro JC;Ma J;Song M;Partridge DG;Kirkevåg A;Leong Y;Hu WW;Taylor NF;Lambe A;Cerully K;Bougiatioti A;Liu P;Krejci R;Petäjä T;Percival C;Davidovits P;Worsnop DR;Ekman AML;Nenes A;Martin S;Jimenez JL;Collins DR;Topping DO;Bertram AK;Zuend A;Virtanen A;Riipinen I
大气有机气溶胶的很大一部分来自自然排放，这些排放在大气中被氧化形成二次有机气溶胶(SOA)。异戊二烯(IP)和单萜烯(MT)是起源于森林的最重要的SOA前体。目前，气候变化对气候的影响是通过水吸收的参数估计的，这极大地简化了气候变化的复杂性。我们将实验室实验、热力学模拟、野外观测和气候模拟相结合，以(1)解释依赖于RH的SOA吸水与溶解度和相分离的分子机制；(2)表明实验室关于IP-和MT-SOA吸湿性的数据代表了具有相应的OA源剖面的环境数据；以及(3)展示了所模拟的气溶胶气候效应对假设的OA水亲和力的敏感性。我们的结论是，在量化有机气溶胶的气候影响时，常用的单参数吸湿性框架会引入显著的误差。这些结果突出表明，需要更好地限制全球海洋油酸的总体质量负荷及其分子组成，包括目前未充分开发的人为油酸和海洋油酸来源。相分离效应解释了生物次生有机气溶胶(SOA)在过饱和和过饱和状态下亲水性的差异。单萜和异戊二烯的实验数据代表了现场观测数据和相应的气相有机剖面。有机气溶胶-水相互作用对全球气候的重要性受高度不确定的有机气溶胶预算控制
A large fraction of atmospheric organic aerosol (OA) originates from natural emissions that are oxidized in the atmosphere to form secondary organic aerosol (SOA). Isoprene (IP) and monoterpenes (MT) are the most important precursors of SOA originating from forests. The climate impacts from OA are currently estimated through parameterizations of water uptake that drastically simplify the complexity of OA. We combine laboratory experiments, thermodynamic modeling, field observations, and climate modeling to (1) explain the molecular mechanisms behind RH‐dependent SOA water‐uptake with solubility and phase separation; (2) show that laboratory data on IP‐ and MT‐SOA hygroscopicity are representative of ambient data with corresponding OA source profiles; and (3) demonstrate the sensitivity of the modeled aerosol climate effect to assumed OA water affinity. We conclude that the commonly used single‐parameter hygroscopicity framework can introduce significant error when quantifying the climate effects of organic aerosol. The results highlight the need for better constraints on the overall global OA mass loadings and its molecular composition, including currently underexplored anthropogenic and marine OA sources. Phase separation effects explain differences in water affinity of biogenic secondary organic aerosol (SOA) at subsaturation and supersaturation Laboratory data for monoterpene and isoprene SOA are representative of field observations with corresponding gas‐phase organic profiles Importance of organic aerosol‐water interactions for global climate is governed by highly uncertain organic aerosol budgets