Global and regional model simulations of atmospheric ammonia
Global and regional model simulations of atmospheric ammonia
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DOI：
10.1016/j.atmosres.2019.104702
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发表时间：
2020-04-01
影响因子：
5.5
通讯作者：
Shallcross, D. E.
中科院分区：
文献类型：
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作者：
Khan, M. A. H.;Lowe, D.;Shallcross, D. E.
氨（NH3）是一种重要的大气利益的基本气体，因为它的作用，在可能形成的细颗粒物，因为它是一个固定的氮在土壤和植物的来源。本文利用全球化学输送模式STOCHEM-CRI和区域气象化学耦合模式WRF-Chem-CRI两个三维模式对大气中NH3的过程进行了模拟。根据STOCHEM-CRI模拟分析，计算了干沉积（24.6 Tg（N）/年）、湿沉积（20.8 Tg（N）/年）、NH 4+形成（25.6 Tg（N）/年）和与OH反应（1.7 Tg（N）/年）的NH3去除通量。计算出全球年平均负担为0.22 Tg（N），寿命为1.1天。OH、NO3和稳定Criegee中间体的气相损失分别占对流层NH3总损失的2.3%、< 1%和<1%。NH3浓度最高的地区是南亚和东亚地区，这主要与农业NH3排放有关。由于臭氧的丰富，沿着赤道通过与OH反应而损失的表面NH3增加了25%。卫星观测和模式结果的比较，可以更好地了解大气中NH3的时空变化在全球和区域尺度上。在模型中使用人为的季节性NH3排放类，季节性NH3的代表性较差。非洲和南美洲所有季节的正偏差可能是由于模型中的来源不确定，例如模型中采用的生物质燃烧NH3排放量被低估。在西北欧夏季的区域模型结果偏低的测量相比，这表明要么失踪的来源，或在该地区的损失过程过于有效。
Ammonia (NH3) is a basic gas of significant atmospheric interest because of its role in the possible formation of fine particulates and because it is a source of fixed nitrogen in soils and plants. NH3 processing in the atmosphere has been simulated using two 3-D models: the global chemistry transport model, STOCHEM-CRI and the regional coupled meteorological-chemical model, WRF-Chem-CRI. From analysis of STOCHEM-CRI simulations, NH3 removal fluxes of dry deposition (24.6 Tg(N)/yr), wet deposition (20.8 Tg(N)/yr), NH4+ formation (25.6 Tg(N)/yr) and reaction with OH (1.7 Tg(N)/yr) have been calculated, making a global annual average burden of 0.22 Tg(N) and life-time of 1.1 days. The gas-phase loss by OH, NO3 and stabilized Criegee intermediates contribute 2.3%, < 1% and < 1%, respectively to the total global loss of tropospheric NH3. The highest concentrations of NH3 are found to be in the region of South and East Asia, which are associated mostly with agricultural NH3 emissions. Loss of surface NH3 by reaction with OH increases by up to 25% along the equator because of the abundances of ozone. Comparison of satellite observations and model results give a better understanding of the temporal and spatial variations of atmospheric NH3 on a global and regional scales. Using the anthropogenic seasonal NH3 emission class in the model gives a poor representation of seasonal NH3. The positive bias in Africa and South America for all seasons is likely due to undetermined sources in the model such as underestimated biomass burning emissions of NH3 adopted in the model. The regional model results over North-West Europe during summer months are biased low compared with the measurements-suggesting either missing sources, or too efficient loss processes in the region.