Processes influencing ozone levels in Alaskan forest fire plumes during long-range transport over the-猫眼课题宝

DOI：

10.1029/2006jd007576

发表时间：

2007-05

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其他

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作者：

E. Real;K. Law;B. Weinzierl;Monika Fiebig;A. Petzold;O. Wild;J. Methven;S. Arnold;A. Stohl;H. Huntrieser;A. Roiger;H. Schlager;D. Stewart;M. Avery;G. Sachse;E. Browell;R. Ferrare;D. Blake

[1]使用拉格朗日方法分析了从阿拉斯加到欧洲的生物质燃烧羽流的长距离传输的情况。在IGAC拉格朗日2K 4实验期间，该羽流在北美、北大西洋和欧洲的自由对流层中被三架不同的飞机多次取样，该实验是2004年夏季ICARTT/ ITOP密集测量的一部分。烟羽中的测量结果表明，CO，VOCs和NOy的值增加，主要是在PAN的形式。观察到的O-3水平在5天内增加了17 ppbv。一个光化学轨迹模型，CiTTyCAT，被用来检查负责的化学演变的羽流的过程。该模型初始化与迎风数据和顺风测量进行比较。使用羽流中的原位气溶胶测量和光学深度的激光雷达检索作为模型中运行的光解代码（Fast-J）的输入，研究了高气溶胶负载对羽流中光解速率的影响。光化学的显着影响被发现与减少18%的O-3生产和24%的O-3破坏超过5天时，包括气溶胶。羽被发现是化学活性与大的O-3增加主要归因于PAN分解过程中下降的羽向欧洲。预测的O-3变化非常依赖于运输过程中的温度变化，也对低对流层中的水蒸气水平，这可能导致O-3的破坏。混合/稀释的模拟是必要的，以重现观测到的污染物水平的羽流。混合模拟使用背景浓度的测量在空气质量中的密切接近的羽流，和混合的时间尺度（平均6.25天）来自CO的变化。观测和模拟的O-3/CO的相关性在羽流进行了比较，以评估模型中的光化学。观察到的斜率在5天内从负值变为正值。这种变化，这在很大程度上可以归因于光化学，是很好地再现了多个模型运行，即使斜率值略有低估，这表明一个小的低估在模拟光化学O-3生产。还通过将模型再运行5天，并与在少女峰等地面站点收集的数据进行比较，研究了这种生物质燃烧羽流对欧洲边界层O-3水平的可能影响，这些数据显示O-3水平略有增加，CO水平升高。该模型预测在整个10天的时间内，由于光化学的O-3的显着变化，但由于稀释的影响，信号在很大程度上丢失。然而，在欧洲的其他几个BB羽的测量表明，O-3的影响阿拉斯加火灾可能是在欧洲显着。

[1] A case of long-range transport of a biomass burning plume from Alaska to Europe is analyzed using a Lagrangian approach. This plume was sampled several times in the free troposphere over North America, the North Atlantic and Europe by three different aircraft during the IGAC Lagrangian 2K4 experiment which was part of the ICARTT/ ITOP measurement intensive in summer 2004. Measurements in the plume showed enhanced values of CO, VOCs and NOy, mainly in form of PAN. Observed O-3 levels increased by 17 ppbv over 5 days. A photochemical trajectory model, CiTTyCAT, was used to examine processes responsible for the chemical evolution of the plume. The model was initialized with upwind data and compared with downwind measurements. The influence of high aerosol loading on photolysis rates in the plume was investigated using in situ aerosol measurements in the plume and lidar retrievals of optical depth as input into a photolysis code (Fast-J), run in the model. Significant impacts on photochemistry are found with a decrease of 18% in O-3 production and 24% in O-3 destruction over 5 days when including aerosols. The plume is found to be chemically active with large O-3 increases attributed primarily to PAN decomposition during descent of the plume toward Europe. The predicted O-3 changes are very dependent on temperature changes during transport and also on water vapor levels in the lower troposphere which can lead to O-3 destruction. Simulation of mixing/dilution was necessary to reproduce observed pollutant levels in the plume. Mixing was simulated using background concentrations from measurements in air masses in close proximity to the plume, and mixing timescales ( averaging 6.25 days) were derived from CO changes. Observed and simulated O-3/CO correlations in the plume were also compared in order to evaluate the photochemistry in the model. Observed slopes change from negative to positive over 5 days. This change, which can be attributed largely to photochemistry, is well reproduced by multiple model runs even if slope values are slightly underestimated suggesting a small underestimation in modeled photochemical O-3 production. The possible impact of this biomass burning plume on O-3 levels in the European boundary layer was also examined by running the model for a further 5 days and comparing with data collected at surface sites, such as Jungfraujoch, which showed small O-3 increases and elevated CO levels. The model predicts significant changes in O-3 over the entire 10 day period due to photochemistry but the signal is largely lost because of the effects of dilution. However, measurements in several other BB plumes over Europe show that O-3 impact of Alaskan fires can be potentially significant over Europe.

Processes influencing ozone levels in Alaskan forest fire plumes during long-range transport over the

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