Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic
Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic
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北大西洋低空人为羽流处理的拉格朗日分析
DOI：
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发表时间：
2008
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通讯作者：
D. Parrish
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作者：
E. Real;K. Law;H. Schlager;A. Roiger;H. Huntrieser;J. Methven;M. Cain;J. Holloway;J. Neuman;T. Ryerson;F. Flocke;J. Gouw;E. Atlas;S. Donnelly;D. Parrish
使用拉格朗日框架研究了来自纽约/波士顿地区的人为羽流在低海拔经过北大西洋运输到欧洲西海岸期间的光化学演化。这种最初受到严重污染的羽流，由研究飞机连续三天在北美东海岸附近进行了采样，然后在爱尔兰西海岸顺风三天，另一架飞机对轻度污染的羽流进行了重新采样。使用光化学轨迹模型（包括沉积和混合效应）再现运输过程中痕量气体浓度的变化。化学和湿沉积处理主导了羽流中所有污染物的演变。平均净光化学 O3 产量估计为 -5 ppbv/天，导致羽流到达欧洲时 O3 含量较低。没有 HNO3 湿沉积的模型运行预测，由于 HNO3 光解导致 NOx 水平增加，因此 O3 平均净破坏量要低得多，为 -1 ppbv/天。这表明 HNO3 的湿沉降间接造成了羽流输送过程中臭氧净破坏的 80%。如果羽流没有遇到降水，到达欧洲时，O3 浓度将高达 80 至 90 ppbv，CO 浓度将在 120 至 140 ppbv 之间。由于高水平的 O3 和水蒸气，光化学破坏在羽流 CO 的演变中也发挥了比混合更重要的作用，这表明 CO 不能总是用作污染气团的示踪剂，特别是在低海拔输送的羽流中。结果还表明，在这种情况下，O3/CO 斜率的增加可归因于 CO 的光化学破坏，而不是通常假设的光化学 O3 产生。
The photochemical evolution of an anthropogenic plume from the New-York/Boston region during its transport at low altitudes over the North Atlantic to the European west coast has been studied using a Lagrangian framework. This plume, originally strongly polluted, was sampled by research aircraft just off the North American east coast on 3 successive days, and then 3 days downwind off the west coast of Ireland where another aircraft re-sampled a weakly polluted plume. Changes in trace gas concentrations during transport are reproduced using a photochemical trajectory model including deposition and mixing effects. Chemical and wet deposition processing dominated the evolution of all pollutants in the plume. The mean net photochemical O3 production is estimated to be −5 ppbv/day leading to low O3 by the time the plume reached Europe. Model runs with no wet deposition of HNO3 predicted much lower average net destruction of −1 ppbv/day O3, arising from increased levels of NOx via photolysis of HNO3. This indicates that wet deposition of HNO3 is indirectly responsible for 80% of the net destruction of ozone during plume transport. If the plume had not encountered precipitation, it would have reached Europe with O3 concentrations of up to 80 to 90 ppbv and CO between 120 and 140 ppbv. Photochemical destruction also played a more important role than mixing in the evolution of plume CO due to high levels of O3 and water vapour showing that CO cannot always be used as a tracer for polluted air masses, especially in plumes transported at low altitudes. The results also show that, in this case, an increase in O3/CO slopes can be attributed to photochemical destruction of CO and not to photochemical O3 production as is often assumed.