a Center for Energy & Environmental Sustainability , Prairie View A&M University , Prairie View , TX.
b Department of Civil & Environmental Engineering , Prairie View A&M University , Prairie View , TX.
J Air Waste Manag Assoc. 2018 Oct;68(10):1051-1064. doi: 10.1080/10962247.2018.1466740. Epub 2018 Jun 28.
The Houston-Galveston-Brazoria (HGB) area of Texas has a history of ozone exceedances and is currently classified under moderate nonattainment status for the 2008 8-hr ozone standard of 75 ppb. The HGB area is characterized by intense solar radiation, high temperature, and high humidity, which influence day-to-day variations in ozone concentrations. Long-term air quality trends independent of meteorological influence need to be constructed for ascertaining the effectiveness of air quality management in this area. The Kolmogorov-Zurbenko (KZ) filter technique, used to separate different scales of motion in a time series, is applied in the current study for maximum daily 8-hr (MDA8) ozone concentrations at an urban site (U.S. Environmental Protection Agency [EPA] Air Quality System [AQS] Site ID: 48-201-0024, Aldine) in the HGB area. This site, located within 10 miles of downtown Houston and the George Bush Intercontinental Airport, was selected for developing long-term meteorologically independent MDA8 ozone trends for the years 1990-2016. Results from this study indicate a consistent decrease in meteorologically independent MDA8 ozone between 2000 and 2016. This pattern could be partially attributed to a reduction in underlying nitrogen oxide (NO) emissions, particularly lowering nitrogen dioxide (NO) levels, and a decrease in the release of highly reactive volatile organic compounds (HRVOCs). Results also suggest solar radiation to be most strongly correlated to ozone, with temperature being the secondary meteorological control variable. Relative humidity and wind speed have tertiary influence at this site. This study observed that meteorological variability accounts for a high of 61% variability in baseline ozone (low-frequency component, sum of long-term and seasonal components), whereas 64% of the change in long-term MDA8 ozone post 2000 could be attributed to NO emission reduction. Long-term MDA8 ozone trend component was estimated to be decreasing at a linear rate of 0.412 ± 0.007 ppb/yr for the years 2000-2016 and 0.155 ± 0.005 ppb/yr for the overall period of 1990-2016.
The effectiveness of air emission controls can be evaluated by developing long-term air quality trends independent of meteorological influences. The KZ filter technique is a well-established method to separate an air quality time series into short-term, seasonal, and long-term components. This paper applies the KZ filter technique to MDA8 ozone data between 1990 and 2016 at an urban site in the greater Houston area and estimates the variance accounted for by the primary meteorological control variables. Estimates for linear trends of MDA8 ozone are calculated and underlying causes are investigated to provide a guidance for further investigation into air quality management of the greater Houston area.
德克萨斯州休斯顿-加尔维斯顿-布拉索里亚（HGB）地区曾多次臭氧超标，目前按照 2008 年臭氧 8 小时标准（75ppb），被归类为中度未达标地区。该地区的特点是太阳辐射强烈、温度高、湿度大，这些因素都会影响臭氧浓度的日常变化。为了确定该地区空气质量管理的有效性，需要构建不受气象影响的长期空气质量趋势。柯尔莫哥洛夫-祖尔宾科（KZ）滤波器技术用于分离时间序列中的不同运动尺度，目前用于分析 HGB 地区一个城市站点（美国环保署空气质量系统 [AQS] 站点 ID：48-201-0024，Aldine）的最大日 8 小时（MDA8）臭氧浓度。该站点位于休斯顿市中心和乔治布什洲际机场 10 英里范围内，选择该站点是为了为 1990 年至 2016 年期间开发长期气象独立的 MDA8 臭氧趋势。本研究结果表明，2000 年至 2016 年间，气象独立 MDA8 臭氧呈持续下降趋势。这种模式部分归因于底层氮氧化物（NO）排放的减少，特别是二氧化氮（NO2）水平的降低，以及高反应性挥发性有机化合物（HRVOC）的排放量减少。结果还表明，太阳辐射与臭氧的相关性最强，温度是次要的气象控制变量。相对湿度和风速在该站点的影响较小。本研究观察到，气象变化解释了基线臭氧（低频成分，长期和季节性成分的总和）的 61%的可变性，而 2000 年后长期 MDA8 臭氧变化的 64%可归因于 NO 排放的减少。2000 年至 2016 年期间，长期 MDA8 臭氧趋势以 0.412±0.007 ppb/yr 的线性速率下降，1990 年至 2016 年期间的整体趋势以 0.155±0.005 ppb/yr 的线性速率下降。
通过开发不受气象影响的长期空气质量趋势，可以评估空气排放控制的有效性。KZ 滤波器技术是一种将空气质量时间序列分离为短期、季节性和长期成分的成熟方法。本文应用 KZ 滤波器技术对 1990 年至 2016 年期间休斯顿大都市区一个城市站点的 MDA8 臭氧数据进行分析，并估计主要气象控制变量所解释的方差。计算了 MDA8 臭氧的线性趋势估计值，并对潜在原因进行了调查，为进一步研究休斯顿大都市区的空气质量管理提供了指导。
