Long-lived halocarbon trends and budgets from atmospheric chemistry modelling constrained with measurements in polar firn
Long-lived halocarbon trends and budgets from atmospheric chemistry modelling constrained with measurements in polar firn
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DOI：
10.5194/acp-9-3911-2009
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发表时间：
2009-06
影响因子：
6.3
通讯作者：
P. Martinerie;E. Nourtier-Mazauric;J. Barnola;W. Sturges;D. Worton;E. Atlas;L. K. Gohar;K. Shine;G. Brasseur
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文献类型：
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作者：
P. Martinerie;E. Nourtier-Mazauric;J. Barnola;W. Sturges;D. Worton;E. Atlas;L. K. Gohar;K. Shine;G. Brasseur
摘要。通过比较两个北极和三个南极站点的极地大气测量结果，以及二维大气化学模型和一维大气扩散模型的模拟结果，研究了七种卤化气体（CFC-11、CFC-12、CFC-113、CFC-114、CFC-115、CCl4和SF6）的预算。第一种方法用于根据工业清单的排放趋势计算大气浓度；计算出的浓度趋势被第二种方法用来生成公司的深度浓度剖面。通过与大气站测量值的比较，在边界层上验证了二维大气模式，并通过与气球和FTIR测量值的比较，在垂直方向上验证了CFC-12模式。大气测量提供了上个世纪历史大气浓度的限制条件。使用格林函数方法讨论了公司的年龄分布。最后，我们的结果被用作一个辐射模型的输入，以评估我们的目标气体的辐射强迫。多物种和多地点的大气研究可以更好地约束大气趋势。所有研究气体在公司底部的低浓度，以及它们与我们的模型结果的一致性，证实了它们的自然来源很小。我们的研究结果表明，CFC-11、CFC-12、CFC-113、CFC-115和SF6的排放、汇和趋势受到很好的约束，而CFC-114和CCl4则不是这样。在平流层中被破坏的卤代烃的寿命发生了显著的排放依赖性变化。这是由于它们从地表被排放到平流层被破坏所需的时间造成的。应努力更新和减少氟氯化碳寿命的巨大不确定性。
Abstract. The budgets of seven halogenated gases (CFC-11, CFC-12, CFC-113, CFC-114, CFC-115, CCl4 and SF6) are studied by comparing measurements in polar firn air from two Arctic and three Antarctic sites, and simulation results of two numerical models: a 2-D atmospheric chemistry model and a 1-D firn diffusion model. The first one is used to calculate atmospheric concentrations from emission trends based on industrial inventories; the calculated concentration trends are used by the second one to produce depth concentration profiles in the firn. The 2-D atmospheric model is validated in the boundary layer by comparison with atmospheric station measurements, and vertically for CFC-12 by comparison with balloon and FTIR measurements. Firn air measurements provide constraints on historical atmospheric concentrations over the last century. Age distributions in the firn are discussed using a Green function approach. Finally, our results are used as input to a radiative model in order to evaluate the radiative forcing of our target gases. Multi-species and multi-site firn air studies allow to better constrain atmospheric trends. The low concentrations of all studied gases at the bottom of the firn, and their consistency with our model results confirm that their natural sources are small. Our results indicate that the emissions, sinks and trends of CFC-11, CFC-12, CFC-113, CFC-115 and SF6 are well constrained, whereas it is not the case for CFC-114 and CCl4. Significant emission-dependent changes in the lifetimes of halocarbons destroyed in the stratosphere were obtained. Those result from the time needed for their transport from the surface where they are emitted to the stratosphere where they are destroyed. Efforts should be made to update and reduce the large uncertainties on CFC lifetimes.