An analysis of the trend in ground-level ozone using non-homogeneous poisson processes

This paper provides a method for measuring the long-term trend in the frequency with which ground-level ozone present in the ambient air exceeds the U.S. Environmental Protection Agency's National Ambient Air Quality Standard (NAAQS) for ozone. A major weakness of previous studies that estimate the long-term trend in the very high values of ozone, and therefore the long-term trend in the probability of satisfying the NAAQS for ozone, is their failure to account for the confounding effects of meterological conditions on ozone levels. Meteorological variables such as temperature, wind speed, and frontal passage play an important role in the formation of ground-level ozone. A non-homogenous Poisson process is used to account for the relationship between very high values of ozone and meteorological conditions. This model provides an estimate of the trend in the ozone values after allowing for the effects of meteorological conditions. Therefore, this model provides a means to measure the effectiveness of pollution control programs after accounting for the effects of changing weather conditions. When our approach is applied to data collected at two sites in Houston, TX, we find evidence of a gradual long-term downward trend in the frequency of high values of ozone. The empirical results indicate how possibly misleading results can be obtained if the analysis does not account for changing weather conditions.     

Meteorological and altitudinal influences on the concentration of ozone at Great Dun Fell

Data are presented from 2 complete years of monitoring ozone concentrations at two sites in rural northern England, one a hill top site and the other a valley site in the same vicinity. Comparison between the two sites indicates that whilst daily maximum ozone concentrations, midday concentrations and peak values are similar, the ozone dosage is significantly greater at the higher elevation site. This is clearly seen by comparison of the mean 50th and 98th percentiles, which are 28 ppbv and 61 ppbv, respectively, for the hill top site, and 22 ppbv and 45 ppbv, respectively, for the valley site. Several case studies of the influence of meteorological conditions on ozone concentrations at the two sites are described.     

香港港口近地面O3与氮氧化物浓度变化的多重分形特征

以2012年3月-2014年2月香港葵涌港口大气ρ（O₃）、ρ（NO₂）和ρ（NO_x）的小时均值为研究对象,运用多重分形去趋势互相关分析法,对香港港口近地面ρ（O₃）与ρ（NO₂）和ρ（NO_x）相互作用的多重分形特征进行研究.结果表明:香港港口O₃ vs NO₂[ρ（O₃）vs ρ（NO₂）,下同]的h（2）（广义Hurst指数）为0.80,O₃ vs NO_x[ρ（O₃）vs ρ（NO_x）,下同]的h（2）为0.79,二者的h（2）均大于0.5,表明ρ（O₃）与ρ（NO₂）、ρ（NO_x）间均存在显著的长程交叉相关性.港口ρ（O₃）与ρ（NO₂）、ρ（NO_x）相互关系的多重分形特性在日际和季节上存在显著差异,其中夜晚的O₃ vs NO₂的Δα（分形强度指数）为0.92,O₃ vs NO_x的Δα为0.81,而白天二者的Δα分别为0.59和0.43,说明夜晚的多重分形特征明显强于白天;Δα为春季>夏季>秋冬,表明多重分形程度在春季最强,夏季次之,秋冬季最弱,可能与港口特殊的地理位置和气候条件有关.研究显示,在构建港口ρ（O₃）的预测模型时,需要考虑不同的时间尺度、不同气象条件下ρ（O₃）与ρ（NO₂）、ρ（NO_x）相关性的多重分形特征的差异性.      

2018—2021年京津冀及周边地区“2+26”城市PM2.5与O3污染特征及气象影响

为了解《打赢蓝天保卫战三年行动计划》期间(2018—2020年)以及之后(2021年)我国重点污染区域空气质量情况,并区分排放源控制与气象条件的贡献,本文利用逐小时监测的PM_2.5、O₃浓度以及气象要素数据,研究了2018—2021年京津冀及周边地区“2+26”城市PM_2.5与O₃污染特征,结合KZ (Kolmogorove Zurbenko)滤波方法定量分析了排放源与气象条件对PM_2.5与O₃浓度长期趋势的贡献. 结果表明:①2018—2021年“2+26”城市PM_2.5浓度年均值与O₃-8 h-90th浓度(O₃日最大8 h平均浓度的第90百分位数)均呈逐年下降趋势. 2018—2021年PM_2.5浓度年均值分别为60、57、51和45 μg/m3,河北省南部、河南省与山东省南部PM_2.5浓度年均值均较高;O₃-8 h-90th浓度分别为198、195、179和171 μg/m3,2018年保定市、石家庄市、聊城市与晋城市的O₃-8 h-90th浓度(>210 μg/m3)均较高,而2021年太原市O₃-8 h-90th浓度(192 μg/m3)较高. ②PM_2.5与O₃-8 h浓度(O₃日最大8 h平均浓度)的长期分量在大部分城市受气象条件影响较为明显. 受气象条件影响的PM_2.5浓度长期分量在2018—2020年无明显趋势,在2021年呈下降趋势;受排放源影响的PM_2.5浓度长期分量在2018—2020年呈下降趋势,在2021年无明显趋势. 受气象条件影响的O₃-8 h浓度长期分量在2018—2020年呈下降趋势,在2021年呈上升趋势;受排放源影响的O₃-8 h浓度长期分量在2018年呈下降趋势,在2019—2021年无明显趋势. ③11个气象因子中,温度和相对湿度对PM_2.5与O₃-8 h浓度变化的影响较大,当温度与相对湿度均比前一天升高时,更有利于PM_2.5与O₃-8 h浓度的同时升高. 研究显示,“2+26”城市PM_2.5与O₃污染受气象条件影响显著,温度与相对湿度的变化对判定PM_2.5与O₃-8 h浓度同时升高的现象有一定积极意义.      

Trends in ground level ozone concentrations in the European Union

Following the Council Directive 92/72/EEC on air pollution by ozone the Member States of the European Union have to inform the European Commission on ozone concentrations and exceedances of threshold values within their territory. Using the available information covering the period of 5 years (1994–1998), the data has been analysed for a possible trend in statistical parameters (50- and 98-percentiles) and number and severity of exceedances. Time series are relatively short but the data suggest that there might be a small increasing trend in the 50 percentile values. The ozone peak values, expressed as 98-percentile values or as number of exceedance days tend to decrease. However, these conclusions must be interpreted carefully as on the short time scales considered here meteorological variations and inter-annual changes may play an important role. The decrease in peak values is most likely caused by the decrease in European ozone precursor emissions since 1990; insufficient data is available to explain the increasing 50-percentile values. Possible explanations are an increase in tropospheric ozone background values caused by a world-wide increase in CH₄, CO and NO_x emissions or a reduced ozone titration by reduced NO_x emissions on the local scale. The data submitted under the ozone directive is insufficient to provide firm conclusions on this point.     

基于KZ滤波法的河北省PM2.5和O3浓度不同时间尺度分析研究

大气细粒子和臭氧是影响我国城市空气质量的主要污染物质,其浓度的大小不仅与污染源的排放量有关,气象条件也是影响其浓度分布特征的重要因素.要评估污染物减排措施的效果,有必要将气象条件的影响剥离出来,仅评估排放量的降低对污染物浓度长期变化趋势的影响.本文使用KZ(Kolmogorov-Zurbenko)滤波方法对河北省石家庄、保定、张家口三市2013—2017年PM_(2.5)和O_3逐日浓度时间序列进行分解,并使用同期地面气象观测数据对各时间序列进行逐步回归分析,将经过KZ滤波后的长期序列与经逐步回归后的结果的差值再次进行滤波处理,得到去除气象影响的污染物浓度长期变化趋势,该浓度仅与污染物的排放量有关.结果表明,因污染源排放的影响,河北省三市大气PM_(2.5)浓度在研究年内除在2017年初略有上升以外,其余季节均呈下降趋势.河北省三市大气O_3浓度在研究年内均有波动上升趋势.气象条件对PM_(2.5)浓度长期变化趋势的影响大于O_3.     

Uncertainties in surface ozone trend at hohenpeissenberg

It is well-known that early surface ozone measurements using the iodometric method suffered from both negative and positive interferences by reducing and oxidizing gases, notably SO₂ and NO₂, respectively. These interferences could be serious in areas close to emission sources. Using the important Hohenpeissenberg Observatory surface ozone data series as an example, we demonstrate that the uncertainty due to SO₂ interference during the pre-1976 period could have a significant effect on the apparent upward trend, and possibly lead to its overestimation by a factor of 3. There is evidence to show that the NO₂ interference at the Observatory may not be entirely insignificant under certain meteorological conditions. The effect of the uncertainty due to this interperence on the long-term surface ozone trend also needs to be evaluated. In view of the importance of the conclusions concerning increasing surface ozone concentrations, which have stemmed from previous analyses of the Hohenpeissenberg Observatory data set, it is essential to discuss these uncertainties in the open literature so that a consensus of opinion may be formed on the data quality of the early years' observations.     

海南省背景区域臭氧及其前体物污染特征

基于2019年五指山背景点、海口市和三亚市的环境空气自动监测数据和气象观测资料,分析了海南省背景区域和重点城市O₃及其前体物NO₂污染特征;结合挥发性有机物（VOCs）在线监测数据,分析了五指山背景点VOCs的时间变化规律、O₃浓度高值月份O₃及其前体物VOCs和NO_x的污染特征以及VOCs的臭氧生成潜势（OFP）.结果表明,O₃是影响五指山背景点空气质量的关键污染物,五指山背景点O₃日最大8 h浓度平均值与海口市和三亚市显著相关.背景点NO₂月均浓度水平显著低于城市点,然而背景点和城市点O₃月均浓度水平和变化趋势高度一致.背景点O₃变化与风向密切相关,春夏季偏南风频率较高,O₃浓度相对较低;秋冬季以东北风为主,易受内陆污染输送影响,O₃浓度较高.五指山背景点春夏季VOCs体积分数低于秋冬季,但对应的OFP高于秋冬季;其中异戊二烯夏季体积分数显著高于秋冬季,且其夏季体积分数占总挥发性有机物的比例最高,对应的OFP贡献率可达70%以上,O₃则表现出秋冬季显著高于夏季的特征.11月O₃高浓度时段乙炔和芳香烃的体积分数较清洁日出现较大上升,同时其对应的OFP显著上升.VOCs优势物种和OFP主要贡献物种的分析结果表明,O₃高浓度时段机动车尾气和油气挥发排放源对五指山背景点VOCs的化学组成和OFP有重要贡献.     

Transport,formation and sink processes behind surface ozone variability in north european conditions

Measurements of ozone, nitrogen dioxide and meteorological parameters at the two Finnish EMEP background stations of Ähtäri (forested site) and Utö (an offshore island) show clear indications of the influence of the precursor source areas of Western and Eastern Europe on surface ozone behaviour at these higher latitudes. The mean ozone levels are relatively high, with maximum monthly values of 41 and 42 ppb, respectively. These values occur in April at both sites nearly irrespectively of wind direction, pointing to a global feature. Other spring, as well as summer and autumn, months have lower ozone values for wind direction sectors corresponding to clean air masses (north-westerlies and north-easterlies). Surface uptake is an important sink in the local ozone budget, especially during late spring, summer and early autumn. Chemical losses are more efficient in winter, when the ground is covered by snow.     

Surface ozone in rural,urban and alpine regions of switzerland

The study shows the variation of surface ozone concentrations for six selected sites between 410 and 3569 m elevation. The annual mean values in 1987 for these sites ranged from 10 to 50 ppb. Mean values of ozone as well as frequency of peak values are clearly dependent on the elevation of the site. Apart from elevation the influences of the specific location and exposure to pollutants such as NO and NO₂ are considered. The ratio of the daily means of NO and NO₂ is very well suited to indicate local sources. Mean diurnal concentration variations of nitric oxide and ozone on a slope show a significant influence of topography.     

A two-year study of ozone behaviour at rural and forested sites in Eastern France

Ozone and other gases measurements in three rural sites of different altitudes in eastern France (an area with important forest decline) were used as a basis to understand the mechanisms controlling the ozone behaviour in the lower troposphere. An analysis is presented of the annual variation of the background tropospheric ozone level in order to evaluate its contribution to the surface ozone level. The frequency of occurrence of simultaneous elevated ozone episodes at one urvan and the three rural sites was examined in order to determine the major cause of high ozone levels. The relation between elevated ozone concentrations and wind direction was also investigated. It was found that the majority of high ozone concentration episodes take place simultaneously at the three sites, showing an elevated occurrence of episodes of regional origins. Most of the episodes are associated with the east wind sector.     

大连市区近地面臭氧污染规律研究及与PM2.5等污染物的相关性分析

2013年大连市区大气中臭氧日最大8小时平均值第90百分位为0.099毫克/立方米,符合二级标准（GB3095-2012）日最大8小时平均。点日最大8小时平均超标率为1.0%。春、秋两季的日最大8小时平均较大,但都符合二级标准,从月份变化看,5月的日最大8小时平均最高,12月最低,从24小时变化看,14时、15时和16时的臭氧均值最高,7时臭氧均值最低。从各点位变化看,傅家庄点位臭氧日最大8小时平均的第90百分位最高,双D港点位最低。大连市区臭氧与PM2.5和PM10的负相关性最好,相关系数均达到0.86以上,与二氧化氮、二氧化硫和一氧化碳也呈较好的负相关。     

东亚地区大气整层臭氧浓度的时空变化

从TOMS臭氧全球网格资料截取主要包含中国大陆的东亚地区 (6 9 375°E— 1 39 375°E ;1 4 5°N— 5 4 5°N)的数据 ,分析大气整层臭氧浓度的变化特征 .结果表明 ,区域多年平均臭氧浓度约为 30 7DU(多卜森单位 :DobsonUnit) ;一年中 ,平均臭氧浓度有明显的季节变化 ,春季 (3月 )达最大值 ,秋季 (1 0月 )最小 ,变化幅度约 5 0DU .区域内臭氧浓度具有很强的空间 (纬向 )变化 ,低纬度地区臭氧浓度低 ,较高纬度地区臭氧浓度高 .各地臭氧浓度变化的概率分布基本为单峰型 ,低纬度地区分布较窄而高纬度地区宽 .从 1 978至 1 994年的十多年中 ,区域平均浓度呈明显的下降趋势 ,下降幅度约 1 0DU .对应于此 ,区域内各等级的臭氧浓度值以大致均匀的速率变化 ,低值的出现概率增加 ,而高值的出现概率减小 .     

不同时间尺度气象要素与空气污染关系的KZ滤波研究

空气污染状况受气象要素和污染源排放的共同影响,为了评估大气污染控制措施的效果,需将由污染源排放的浓度数据分离出来.本文利用KZ滤波方法将天津市6个监测站点2015~2017年逐日的O₃、PM_2.5和PM₁₀浓度资料和6个同期气象数据分解为长期分量、短期分量和季节分量,计算各分量对原始时间序列方差的贡献.采用逐步回归法建立O₃及颗粒物3种分量与相应尺度气象要素的线性模型.结果表明,上述3种污染物浓度数据经分解后,季节分量对总方差贡献最大,其次为短期分量;气温和相对湿度是影响O₃季节和短期分量的主要气象因素,其中温度占主导地位,且呈现正相关,与相对湿度呈负相关;风速、气压、降水与颗粒物的短期及季节浓度变化呈负相关,相对湿度与之呈正相关,温度与短期分量呈正相关、与季节分量的变化呈负相关;经逐步回归消除气象影响的PM₁₀的长期分量有波动下降的趋势,PM_2.5浓度在2017年年初有所上升,其余部分有下降趋势,O₃长期分量浓度有所上升;这几年间颗粒物污染控制措施的效果较为显著,O₃污染有所加重.     

Characteristics of urban ozone level in Hong Kong

ＩｎｔｒｏｄｕｃｔｉｏｎＯｚｏｎｅｉｓａｎａｉｒｐｏｌｌｕｔａｎｔｆｏｒｍｅｄｔｈｒｏｕｇｈａｓｅｒｉｅｓｏｆｐｈｏｔｏｃｈｅｍｉｃａｌｒｅａｃｔｉｏｎｉｎｔｒｏｐｏｓｐｈｅｒｅａｎｄｉｓｏｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｐｈｙｔｏｔｏｘｉｃａｉｒｐｏｌｌｕｔａｎｔｓ.Ｉｎｇｅｎｅｒａｌ,ｄｉｒｅｃｔｅｍｉｓｓｉｏｎｏｆｏｚｏｎｅｆｒｏｍａｎｔｈｒｏｐｏｇｅｎｉｃｓｏｕｒｃｅｓｉｓｎｅｇｌｉｇｉｂｌｅｉｎｔｈｅｆｒｅｅｔｒｏｐｏｓｐｈｅｒｅ .Ａｃｃｏｒｄｉｎｇｔｏｔｈｅｓｔｕｄｙｏｎｆｏｒ…     

Sensitivity analysis of surface ozone to emission controls in Beijing and its neighboring area during the 2008 Olympic Games

The regional air quality modeling system RAMS (Regional Atmospheric Modeling System)-CMAQ (Community Multi-scale Air Quality modeling system) is applied to analyze temporal and spatial variations in surface ozone concentration over Beijing and its surrounding region from July to October 2008. Comparison of simulated and observed meteorological elements and concentration of nitrogen oxides (NOx) and ozone at one urban site and three rural sites during Olympic Games show that model can generally reproduce the main observed feature of wind, temperature and ozone, but NOx concentration is overestimated. Although ozone concentration decreased during Olympics, high ozone episodes occurred on 24 July and 24 August with concentration of 360 and 245 μg/m³ at Aoyuncun site, respectively. The analysis of sensitive test, with and without emission controls, shows that emission controls could reduce ozone concentration in the afternoon when ozone concentration was highest but increase it at night and in the morning. The evolution of the weather system during the ozone episodes (24 July and 24 August) indicates that hot and dry air and a stable weak pressure field intensified the production of ozone and allowed it to accumulate. Process analysis at the urban site and rural site shows that under favorable weather condition on 24 August, horizontal transport was the main contributor of the rural place and the pollution from the higher layer would be transported to the surface layer. On 24 July, as the wind velocity was smaller, the impact of transport on the rural place was not obvious.     

挥发性有机物(VOCs)的不同化学去除途径:城市与区域站点的对比

VOCs在大气中主要是与OH自由基、NO₃自由基和O₃等反应氧化去除,部分OVOCs的自身光解也是重要的化学去除途径.本研究基于2018年和2019年秋季在珠三角地区的城市和区域站点的外场观测实验,使用VOCs、常规痕量气体及气象参数的观测数据,对烷烃、烯烃、芳香烃和OVOCs等VOCs组分不同化学去除途径的去除速率进行分析.结果表明,烷烃和芳香烃主要通过与OH自由基反应去除,最高占比超过99%.与NO₃自由基和O₃的反应可贡献烯烃去除速率的80%以上,特别是一些天然源的烯烃（如单萜烯）与NO₃自由基的氧化去除是贡献最大的氧化途径.光解是甲醛最重要的去除途径,在两个站点均达到了50%以上,酮类的光解贡献会高于其他OVOCs类物质.OH自由基的氧化去除途径在城市和区域站点的人为源及天然源VOCs去除中占主导地位.区域站点,烯烃尤其是天然源的烯烃物种,与NO₃自由基和O₃反应的贡献要高于城市站点.本研究对促进不同VOCs物种在大气中的去除途径以及其空间差异的认识有重要意义.     

近20年北京市城近郊区环境空气质量变化及其影响因素分析

利用北京环境空气质量定点监测资料,研究了北京市城近郊区近20年来环境空气质量的变化趋势及其影响因素.结果表明,从年际变化看,SO2、降尘、B[a]P浓度显著下降,而NOx、CO浓度和O3超标情况显著上升,空气污染处于由煤烟型向机动车尾气型转变的过程中,表现出典型的复合污染特征.年内变化显示,采暖期污染比非采暖期严重,尤其SO2在采暖期浓度是非采暖期的5.7倍.从空间分布上看,TSP、降尘、O3表现为近郊区污染重于城区;SO2、NOx、CO表现为城区污染重于近郊区.空气污染源增加的压力与环境保护措施的相互作用是驱动北京市近20年环境空气质量变化的主要因素.产业结构的变化、重点污染源的整治、能源结构调整、能源的清洁使用、机动车尾气排放标准的提高等对保护环境空气质量起到一定作用.     

Characteristics of ozone and ozone precursors (VOCs and NOx) around a petroleum refinery in Beijing, China

A field measurement campaign for ozone and ozone precursors(VOCs and NOx) was conducted in summer 2011 around a petroleum refinery in the Beijing rural region. Three observation sites were arranged, one at southwest of the refinery as the background, and two at northeast of the refinery as the downwind receptors. Monitoring data revealed the presence of serious surface O3 pollution with the characteristics of high average daily mean and maximum concentrations(64.0 and 145.4 ppbV in no-rain days, respectively) and multi-peak diurnal variation. For NOx, the average hourly concentrations of NO2 and NO were in the range of 20.5–46.1 and 1.8–6.4 ppbV, respectively. For VOC measurement, a total of 51 compounds were detected. Normally, TVOCs at the background site was only dozens of ppbC, while TVOCs at the downwind sites reached several hundreds of ppbC. By subtracting the VOC concentrations at background, chemical profiles of VOC emission from the refinery were obtained, mainly including alkanes(60.0% ± 4.3%), alkenes(21.1% ± 5.5%) and aromatics(18.9% ± 3.9%). Moreover, some differences in chemical profiles for the same measurement hours were observed between the downwind sites; the volume ratios of alkanes with low reactivity and those of alkenes with high reactivity respectively showed an increasing trend and a decreasing trend. Finally, based on temporal and spatial variations of VOC mixing ratios, their photochemical degradations and dispersion degradations were estimated to be 0.15–0.27 and 0.42–0.62, respectively, by the photochemical age calculation method, indicating stronger photochemical reactions around the refinery.     

西南地区旱涝特征及其趋势预测

应用Z指数和标准化降水指数SPI,结合REOF方法和Hurst 指数对西南地区旱涝等级及其时空分布规律、演变趋势进行分析和预测,结果表明:SPI 和Z指数的计算结果和现实情况较一致,从多年平均值来看,云南的中甸及四川的石渠、德格等地干旱指数处于低值区,属重旱区。贵州和广西及云南南部部分地区属易涝区。逐年的SPI 和Z指数结果大体一致,2000 年以后,干旱指数波动较大。通过REOF分析,Z指数的分布大致分为川西区、川东(包括渝)区、云贵(包括广西北部)区、广南四个区域。云贵区Z指数总体呈下降趋势,涝情呈减弱趋势;川西区在1964 年至1973 年间干旱严重,1995 年以后变化相对稳定,但干旱也时有发生;川东区旱涝变化不显著。经Hurst 指数分析,西南五省市未来的旱涝情况大致为干旱程度呈逐步加大的态势,洪涝程度呈较弱的逐步减小态势。