Impacts of long-range transport of global pollutants and precursor gases on US air quality under future climatic conditions
Impacts of long-range transport of global pollutants and precursor gases on US air quality under future climatic conditions
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DOI：
10.1029/2007jd009469
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发表时间：
2008-10-15
影响因子：
4.4
通讯作者：
Wang, Julian
中科院分区：
文献类型：
--
作者：
Huang, Ho-Chun;Lin, Jintai;Wang, Julian
美国的空气质量受到美国国内外排放的影响。后一种影响表现为污染物跨越美国边境的远程传输（LRT），这可以通过横向边界条件（LBC）模拟到区域建模系统中。该系统由一个区域空气质量模型（RAQM）组成，该模型将局地源排放和化学过程与由嵌套全球化学输送模型（臭氧和相关化学示踪剂模型（MOZART））预测的LBC的远程强迫整合在一起。现今的模拟显示了重要的轻轨效应，在有臭氧问题的5个主要区域，即美国东北部、美国中西部、德克萨斯州、加利福尼亚州和美国东南部，轻轨效应有所不同。为了确定轻轨影响对预估全球气候和排放变化的响应，在未来时期（2048-2052年和2095-2099年）在两个排放情景（IPCC A1Fi和B1）下重复了MOZART和RAQM模拟。与RAQM模拟的排放情景相比，由MOZART预测的未来美国空气质量对排放情景的敏感性较低，无论是否通过MOZART的LBC纳入LRT效应。考虑LRT效应的RAQM结果显示，地表臭氧混合比对2095-2099年气候排放变化的敏感性最大的地区为美国东南部（-24% ~ +25%），其次为美国东北部和中西部。2095 ~ 2099年，由于轻轨效应的净增加，日平均地表臭氧混合比增加+4% ~ +13%，日平均最大8 h平均臭氧混合比增加+4% ~ +11%。与之相对应的是，2095 ~ 2099年轻轨效应使总塔柱O-3混合比增加了+7% ~ +16%，地表臭氧超标天数也增加了2 ~ 3天。结果表明，未来美国空气质量的变化将受到全球排放的重大影响。
The U. S. air quality is impacted by emissions both within and outside the United States. The latter impact is manifested as long-range transport (LRT) of pollutants across the U. S. borders, which can be simulated by lateral boundary conditions (LBC) into a regional modeling system. This system consists of a regional air quality model (RAQM) that integrates local-regional source emissions and chemical processes with remote forcing from the LBC predicted by a nesting global chemical transport model ( model for ozone and related chemical tracers (MOZART)). The present-day simulations revealed important LRT effects, varying among the five major regions with ozone problems, i.e., northeast United States, midwest United States, Texas, California, and southeast United States. To determine the responses of the LRT impacts to projected global climate and emissions changes, the MOZART and RAQM simulations were repeated for future periods (2048-2052 and 2095-2099) under two emissions scenarios (IPCC A1Fi and B1). The future U. S. air quality projected by the MOZART is less sensitive to the emissions scenarios than that simulated by the RAQM with or without incorporating the LRT effects via the LBC from the MOZART. The result of RAQM with the LRT effects showed that the southeast United States has the largest sensitivity of surface ozone mixing ratio to the emissions changes in the 2095-2099 climate (-24% to +25%) followed by the northeast and midwest United States. The net increase due to the LRT effects in 2095-2099 ranges from +4% to +13% in daily mean surface ozone mixing ratio and +4% to +11% in mean daily maximum 8-h average ozone mixing ratios. Correspondingly, the LRT effects in 2095-2099 cause total column O-3 mixing ratio increases, ranging from +7% to +16%, and also 2 to 3 more days with the surface ozone exceeding the national standard. The results indicate that future U. S. air quality changes will be substantially affected by global emissions.