Active chlorine in the remote marine boundary layer: Modeling anomalous measurements of δ13C in methane
Active chlorine in the remote marine boundary layer: Modeling anomalous measurements of δ13C in methane
复制标题
遥远海洋边界层中的活性氯：对甲烷中 δ13C 的异常测量进行建模
DOI：
10.1029/2001gl013064
复制
发表时间：
2001
影响因子：
5.2
通讯作者：
J. Cainey
中科院分区：
文献类型：
--
作者：
W. Allan;D. Lowe;J. Cainey
在南半球热带外的海洋边界层（MBL）中，甲烷中δ 13 C的测量结果表明，如果羟基自由基是对流层甲烷唯一的汇，则动力学同位素分馏比预期的要大得多。我们使用一个简单的化学箱模型表明，假设MBL活性氯（Cl·）汇存在一个季节性循环，夏季-冬季浓度差为<$6· 10 <$cm−3，则可以解释这些异常观测。所需的夏季最大值和年平均Cl·浓度是合理的，并意味着甲烷的全球Cl·汇强度< 5 Tg yr−1。选择一个Cl·汇的季节性周期与非正弦二甲基硫醚的季节性周期给出了观察到的分馏与一个较小的年平均Cl·浓度比等效的正弦Cl·周期。
Measurements of δ13C in methane in the marine boundary layer (MBL) of the extratropical Southern Hemisphere imply a kinetic isotope fractionation much larger than would be expected if the hydroxyl radical were the only tropospheric methane sink. We use a simple chemical box model to show that the assumption of a MBL active chlorine (Cl•) sink can explain these anomalous observations provided there is a seasonal cycle in the Cl• sink with a summer‐winter concentration difference ∼ 6 · 10³ cm−3. The required summer maximum and yearly mean Cl• concentrations are plausible, and imply a global Cl• sink strength for methane of < 5 Tg yr−1. Choice of a Cl• sink seasonal cycle linked to the nonsinusoidal dimethyl sulfide seasonal cycle gives the observed fractionation with a smaller yearly mean Cl• concentration than equivalent sinusoidal Cl• cycles.