Transport of Asian ozone pollution into surface air over the western United States in spring
Transport of Asian ozone pollution into surface air over the western United States in spring
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DOI：
10.1029/2011jd016961
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发表时间：
2012-02-17
影响因子：
4.4
通讯作者：
Wyman, Bruce
中科院分区：
文献类型：
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作者：
Lin, Meiyun;Fiore, Arlene M.;Wyman, Bruce
许多先前的研究清楚地记录了美国西部的偶发性亚洲污染。S.自由对流层在这里，我们研究了亚洲污染羽流进入美国西部的运输机制。S. 2010年5月至6月，利用新的全球高分辨率（类似于50 x 50 km（2））化学-气候模型（GFDL AM3），通过对现场和卫星测量结果的综合分析，对地表空气进行了研究。我们发现，AM3与全平流层对流层化学轻推再分析风成功地再现观察到的急剧臭氧梯度以上加州，包括交错和混合的亚洲污染和平流层空气与中纬度气旋气流的复杂相互作用。亚洲污染物在冷锋后等熵下降，在800百帕附近，美国西南部臭氧增强最大。美国，包括人口稠密的洛杉矶盆地。在强烈的事件，亚洲的排放量可以贡献8-15 ppbv的臭氧在模型的日子里，观察到的每日最大8小时平均臭氧（MDA 8 O-3）超过60 ppbv。我们发现，在亚洲人为排放的情况下，20%的MDA 8 O-3的60 ppbv在模型中的排放量不会发生在美国西南部。对于75 ppbv的阈值，该统计数据增加到53%。我们的分析表明，亚洲排放的潜力，以促进高-O-3事件在美国西部高海拔地区，在该地区实现更严格的臭氧标准的影响。我们进一步展示了一个概念验证的方法，使用卫星CO柱测量作为一个定性预警指标，预测亚洲臭氧污染事件在美国西部。S.交货时间为1-3天。
Many prior studies clearly document episodic Asian pollution in the western U. S. free troposphere. Here, we examine the mechanisms involved in the transport of Asian pollution plumes into western U. S. surface air through an integrated analysis of in situ and satellite measurements in May-June 2010 with a new global high-resolution (similar to 50 x 50 km(2)) chemistry-climate model (GFDL AM3). We find that AM3 with full stratosphere-troposphere chemistry nudged to reanalysis winds successfully reproduces observed sharp ozone gradients above California, including the interleaving and mixing of Asian pollution and stratospheric air associated with complex interactions of midlatitude cyclone air streams. Asian pollution descends isentropically behind cold fronts; at similar to 800 hPa a maximum enhancement to ozone occurs over the southwestern U. S., including the densely populated Los Angeles Basin. During strong episodes, Asian emissions can contribute 8-15 ppbv ozone in the model on days when observed daily maximum 8-h average ozone (MDA8 O-3) exceeds 60 ppbv. We find that in the absence of Asian anthropogenic emissions, 20% of MDA8 O-3 exceedances of 60 ppbv in the model would not have occurred in the southwestern USA. For a 75 ppbv threshold, that statistic increases to 53%. Our analysis indicates the potential for Asian emissions to contribute to high-O-3 episodes over the high-elevation western USA, with implications for attaining more stringent ozone standards in this region. We further demonstrate a proof-of-concept approach using satellite CO column measurements as a qualitative early warning indicator to forecast Asian ozone pollution events in the western U. S. with lead times of 1-3 days.