An idealized two-dimensional approach to study the impact of the West African monsoon on the meridional gradient of tropospheric ozone
An idealized two-dimensional approach to study the impact of the West African monsoon on the meridional gradient of tropospheric ozone
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研究西非季风对对流层臭氧经向梯度影响的理想化二维方法
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发表时间：
2008
期刊：
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通讯作者：
J. Pinty
中科院分区：
文献类型：
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作者：
M. Saunois;C. Mari;V. Thouret;J. Cammas;P. Peyrillé;J. Lafore;B. Sauvage;A. Volz;P. Nédélec;J. Pinty
[1] Meso-NH 模型的理想化垂直经向区域对称版本用于研究对流层臭氧对西非季风动态的响应，以及地表排放和闪电产生的氮氧化物 (LNOx)。动态模型中添加了 O3-NOx-VOC 化学方案，包括表面排放和 LNOx 生产的参数化。模型显示，地表排放的臭氧前体受到深对流抬升，然后在热带辐合带（ITCZ）两侧哈德来环流上分支中进行平流输送。闪电产生的氮氧化物促进对流层中上层CO和VOC氧化产生化学臭氧。对流和化学趋势的分析表明，ITCZ 的臭氧极小值是由贫臭氧气团排放到对流层上层引起的。由于缺乏与高纬度地区的交换和纬向方向的通风，二维模型存在局限性。尽管存在这些限制，灵敏度模拟表明，LNOx 源和生物 VOC 对于产生臭氧经向梯度是必要的，该梯度是通过哈德利环流南部在役的空中客车飞机 (MOZAIC) 飞机对臭氧和水蒸气的测量所观察到的。还需要 LNOx 源来将哈德利环流北部的经向臭氧梯度维持在 24°N。在没有 LNOx 源的情况下，模拟的对流层上层 O3 经向梯度范围为 0.22 至 0.52 ppbv/deg，在有 LNOx 源的情况下，在南部和北部单元中分别为 0.60 至 1.08 ppbv/deg。
[1] An idealized vertical-meridional zonally symmetrical version of the Meso-NH model is used to study the response of tropospheric ozone to the dynamics of the West African monsoon, as well as surface emissions and NOx-production by lightning (LNOx). An O3-NOx-VOC chemical scheme has been added to the dynamical model, including surface emissions and a parameterization of the LNOx production. The model shows that the ozone precursors emitted at the surface are uplifted by deep convection and then advected in the upper branches of the Hadley cells on both sides of the Inter Tropical Convergence Zone (ITCZ). The NOx produced by lightning promotes chemical ozone production in the middle and upper troposphere from the oxidation of CO and VOCs. The analysis of the convective and chemical tendencies shows that the ozone minimum at the ITCZ is induced by venting of ozone-poor air masses into the upper troposphere. The bi-dimensional model suffers from limitations due to the absence of exchange with the higher latitudes and ventilation in the zonal direction. Despite of these restrictions, sensitivity simulations show that the LNOx source and biogenic VOCs are necessary to create the meridional gradient of ozone observed by the Measurements of OZone and water vapor by in-service AIrbus airCraft (MOZAIC) aircrafts in the southern Hadley cell. The LNOx source is also required to maintain the meridional ozone gradient up to 24°N in the northern Hadley cell. The modeled meridional gradient of O3 in the upper troposphere ranges from 0.22 to 0.52 ppbv/deg without the LNOx source and from 0.60 to 1.08 ppbv/deg with the LNOx source, in the southern and the northern cells respectively.