Estimating North American background ozone in U.S. surface air with two independent global models: Variability, uncertainties, and recommendations
Estimating North American background ozone in U.S. surface air with two independent global models: Variability, uncertainties, and recommendations
复制标题
DOI：
10.1016/j.atmosenv.2014.07.045
复制
发表时间：
2014-10-01
影响因子：
5
通讯作者：
Milly, G. P.
中科院分区：
文献类型：
--
作者：
Fiore, A. M.;Oberman, J. T.;Milly, G. P.
为了制定和实施可达到的国家臭氧标准，需要对美国地面空气中的北美本底臭氧(NAB)臭氧(O-3)进行准确的估计。这些估计依赖于大气化学传输模型的模拟，这些模型将北美的人为排放设定为零，到目前为止，这些模型严重依赖于一个全球模型。我们使用两个独立的全球模式(GEOS-Chem和GFDL AM3)检验了NAB对2006年春季和夏季的估计。我们评估了基本模拟，其中包括北美的人为排放，以及从空间和地面测量的对流层中的O-3。这些模型经常将观测值括起来，这意味着开发一种多模型方法来估计NABO-3的价值。与早先的研究一致，这些模型有力地模拟了美国西部高海拔地区全国范围内最大的NAB水平(春季的季节平均每日最大8小时值类似于40-50 ppb，夏季类似于25-40 ppb)，其中NAB水平与观测到的O-3相关。在这些地点，27年的GFDL AM3模拟模拟了观测到的60 ppb以上的O-3事件，并表明NAB O-3的年际变化影响了它们的年度频率(在个别事件期间，NAB贡献了50-60 ppb或更多)。在美国东部(EUS)的夏季，当区域人为排放的光化学产量达到峰值时，NAB与观测值基本不相关，低于高海拔地区(平均值类似于20-30ppb)。有四个过程在很大程度上造成了特定区域和季节的模式差异：闪电、NOx生物来源的异戊二烯排放和化学、野火和平流层到对流层的输送。GFDL AM3和GEOS-Chem模式中这些过程表示的差异对NAB估计的不确定性造成了更大的影响，特别是在NAB最高的春季，比在单一模式(GEOS-Chem)中选择水平分辨率更大。我们建议，未来的努力将寻求通过对多个平台上的O-3和相关物种的观测评估的多模式模拟的有针对性的分析来限制这些过程，从而减少空气质量规划所需的NAB估计的误差。(C)2014爱思唯尔有限公司。保留所有权利。
Accurate estimates for North American background (NAB) ozone (O-3) in surface air over the United States are needed for setting and implementing an attainable national O-3 standard. These estimates rely on simulations with atmospheric chemistry-transport models that set North American anthropogenic emissions to zero, and to date have relied heavily on one global model. We examine NAB estimates for spring and summer 2006 with two independent global models (GEOS-Chem and GFDL AM3). We evaluate the base simulations, which include North American anthropogenic emissions, with mid-tropospheric O-3 retrieved from space and ground-level O-3 measurements. The models often bracket the observed values, implying value in developing a multi-model approach to estimate NAB O-3. Consistent with earlier studies, the models robustly simulate the largest nation-wide NAB levels at high-altitude western U.S. sites (seasonal average maximum daily 8-h values of similar to 40-50 ppb in spring and similar to 25 -40 ppb in summer) where it correlates with observed O-3. At these sites, a 27-year GFDL AM3 simulation simulates observed O-3 events above 60 ppb and indicates that year-to-year variations in NAB O-3 influence their annual frequency (with NAB contributing 50-60 ppb or more during individual events). During summer over the eastern United States (EUS), when photochemical production from regional anthropogenic emissions peaks, NAB is largely uncorrelated with observed values and it is lower than at high-altitude sites (average values of similar to 20-30 ppb). Four processes contribute substantially to model differences in specific regions and seasons: lightning NOx biogenic isoprene emissions and chemistry, wildfires, and stratosphere-to-troposphere transport. Differences in the representations of these processes within the GFDL AM3 and GEOS-Chem models contribute more to uncertainty in NAB estimates, particularly in spring when NAB is highest, than the choice of horizontal resolution within a single model (GEOS-Chem). We propose that future efforts seek to constrain these processes with targeted analysis of multi-model simulations evaluated with observations of O-3 and related species from multiple platforms, and thereby reduce the error on NAB estimates needed for air quality planning. (C) 2014 Elsevier Ltd. All rights reserved.