New constraints on terrestrial and oceanic sources of atmospheric methanol
New constraints on terrestrial and oceanic sources of atmospheric methanol
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DOI：
10.5194/acp-8-6887-2008
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发表时间：
2008-01-01
影响因子：
6.3
通讯作者：
Williams, J.
中科院分区：
文献类型：
--
作者：
Millet, D. B.;Jacob, D. J.;Williams, J.
我们使用一个全球3-D化学传输模型（GEOS-Chem）来解释新的飞机，地面和海洋观测甲醇的限制，他们放置在大气中的甲醇预算。最近测量的甲醇浓度在海洋混合层（OML）意味着，在原位生物生产必须是主要的甲醇来源的OML，占主导地位的吸收从大气中。因此，海洋排放和吸收必须被视为大气甲醇预算中的独立条款。我们推断，海洋生物圈是大气中甲醇的一个主要来源（85 Tg a（-1）），也是一个大的汇（101 Tg a（-1）），在数量上与大气中OH的氧化（88 Tg a（-1））相当。模型中甲醇的大气寿命为4.7天。在北美边界层的飞机测量表明，陆地植物是一个比目前认为的弱得多的源，可能反映了阔叶树排放量的高估，这也是一般与地面测量一致。我们推断出一个80 Tg a（-1）的陆地植物源，与海洋源的大小相当。在北美夏季，飞机测量显示出与CO的强相关性（R-2= 0.51-0.61）。我们重现这种相关性和斜率的模型与减少植物源，这也证实了人为来源的甲醇必须是小的。我们减少的植物源也提供了一个更好的模拟甲醇观测在热带南美洲。
We use a global 3-D chemical transport model (GEOS-Chem) to interpret new aircraft, surface, and oceanic observations of methanol in terms of the constraints that they place on the atmospheric methanol budget. Recent measurements of methanol concentrations in the ocean mixed layer (OML) imply that in situ biological production must be the main methanol source in the OML, dominating over uptake from the atmosphere. It follows that oceanic emission and uptake must be viewed as independent terms in the atmospheric methanol budget. We deduce that the marine biosphere is a large primary source (85 Tg a(-1)) of methanol to the atmosphere and is also a large sink (101 Tg a(-1)), comparable in magnitude to atmospheric oxidation by OH (88 Tg a(-1)). The resulting atmospheric lifetime of methanol in the model is 4.7 days. Aircraft measurements in the North American boundary layer imply that terrestrial plants are a much weaker source than presently thought, likely reflecting an overestimate of broadleaf tree emissions, and this is also generally consistent with surface measurements. We deduce a terrestrial plant source of 80 Tg a(-1), comparable in magnitude to the ocean source. The aircraft measurements show a strong correlation with CO (R-2= 0.51-0.61) over North America during summer. We reproduce this correlation and slope in the model with the reduced plant source, which also confirms that the anthropogenic source of methanol must be small. Our reduced plant source also provides a better simulation of methanol observations over tropical South America.