利用SAGE Ⅱ卫星资料分析青藏高原上空臭氧垂直廓线

利用1985-2002年SAGE Ⅱ卫星资料获取青藏高原地区上空大气臭氧垂直廓线,分析其变化规律.结果表明:①卫星资料与地面臭氧探空资料有很好的一致性;②青藏高原上空大气臭氧垂直廓线存在南北间的差异和季节变化,夏秋季臭氧廓线极大值出现的位置比冬春季高出1～2 km(高原南部)和2～3 km(高原北部);③臭氧数浓度在10～20 km的高度存在明显季节和南北区域差异;④与同纬度其他地区的平均值相比,夏季(6-9月)臭氧低值主要出现在15～20 km的高原对流层顶附近,最低值出现在18 km附近,而冬季这种差异相对较小.      

Heterogeneous chemistry on polar stratospheric clouds

Polar stratospheric clouds play a crucial role in the depletion of stratospheric ozone over Antarctica in the spring months. The cloud particles promote the conversion of the inert chlorine reservoirs HCl and ClONO₂ to Cl₂, which is photolytically active. Furthermore, the clouds lead to the removal of nitric acid and nitrogen oxides from the gas phase, facilitating the destruction of ozone by catalytic cycles involving chlorine free radicals.     

Methane reductions: Implications for global warming and atmospheric chemical change

Atmospheric methane (CH₄) concentrations have more than doubled over the last two centuries. These increases may contribute to global warming, enhance formation of tropospheric ozone, suppress OH and affect stratospheric ozone. Calculations show that stabilization of CH₄ could reduce projected temperature increases and possibly mitigate background tropospheric O₃ increases due to increasing levels of CH₄.     

高能电子沉降对北半球冬季中高层大气活性氮和臭氧影响的数值模拟

高纬度地区平流层臭氧浓度对极地地表生物地球化学过程影响巨大,近年来高能电子沉降对大气臭氧和活性氮的影响成为新的关注点。本工作基于化学-气候耦合模式SOCOL3.0,参考第六次耦合模式比较计划（CMIP6）推荐的低能量电子（LEE）和中能量电子（MEE）的参数化方案构建了SOCOL-EPP-ECNU化学-气候模式,利用该模式对高能电子沉降对中高层大气活性氮（NO_x）和臭氧的影响进行了敏感性试验和评估。结果表明,中高层大气对于LEE效应产生的NO_x通量的上边界条件设定敏感度很高,该设定对模式模拟效果有决定性意义。加入LEE和MEE通量后,模式对北半球冬季平流层中下层NO_x浓度的模拟精度得到提高,同时也使北半球冬季平流层中下层气温的模拟得到改善。模拟结果指示,加入LEE和MEE,进一步完善对高能粒子沉降的模式描述,有助于提高模式对大气化学成分及气候要素模拟的准确度。     

青藏高原纳木错湖水主要化学离子的时空变化特征

为揭示青藏高原纳木错湖水化学离子的时空变化特征、来源以及主要控制因子,于2006～2010年连续定点(30°47.27’N,90°58.53’E,4 718 m a.s.l.)采集近岸表层湖水样品;于2009年8月采集湖心区剖面样品;于2010年10月采集湖心区剖面样品及表层湖水样品;对其主要化学离子进行分析.结果表明,纳木错湖水中主要阳离子为Na+,主要阴离子为HCO3-.绝大多数离子浓度在季风期较高(6～9月),而非季风期尤其是封冻期(1～4月)偏低;Ca2+浓度的变化则相反,即封冻期较高,而非封冻期较低且变化较小.对垂直剖面湖水分析表明,在湖水垂直结构稳定的非季风期(如10月),除Ca2+浓度随深度无显著变化外,其他离子浓度随深度增加而增大.纳木错湖水主要离子来源于入湖河水的贡献;影响离子时空变化的因素包括蒸发、降水、pH值等,其中蒸发是最主要的影响因素,它造成湖水Na+浓度不断升高而Ca2+浓度降低.     

The ozone record at Payerne: An assessment of the cross-tropopause flux

Ozone soundings from the 21-year record at Payerne (47°N, 7°E) are analysed. At the 300 mb level a simple statistical technique makes it possible to distinguish between the ozone of tropospheric photochemical origin and that in stratospheric intrusions. It is estimated that stratospheric intrusion is the source of 25% of the observed ozone mixing ratio at 300 mb. The maximum stratosphere to troposhere flux of ozone occurs in late winter/spring.A box model is developed for a Northern Hemisphere troposphere with stratosphere-troposphere exchange parameterized in terms of the baroclinic eddy activity but no tropospheric in situ source of ozone. It shows the same seasoanlity in ozone mixing ratio as the Payerne data, suggesting the assumed exchange mechanism to be reasonable.     

Review on the applications of Tropospheric Emissions Spectrometer to air-quality research: Perspectives for China

The Tropospheric Emissions Spectrometer (TES) aboard the National Aeronautics and Space Administration’s (NASA’s) Aura satellite launched in July 2004 is the first satellite instrument to provide simultaneous retrievals of ozone (O₃) and carbon monoxide (CO) throughout the Earth’s lower atmosphere. This paper briefly reviews the TES instrument, the retrieval of O₃ and CO profiles, and the validation of the retrievals. The applications of TES O₃ and CO products include mapping the vertical and horizontal distribution of tropospheric O₃ and CO and their correlations, examining the regional and continental outflow, and analyzing the variability of the two species associated with certain weather and climatic conditions, such as El Ni?o and the Asian monsoon. TES retrievals of O₃ and CO offer an important new source of satellite data over China with good spatial and temporal coverage that can provide evaluation and constraints on the performance of chemical transport models in simulating the general features of ozone pollution over China. Special observations have been conducted and requests may be submitted to the TES team to make geographically focused observations of O₃ and CO over China.     

广州番禺大气成分站复合污染过程VOCs对O3与SOA的生成潜势

通过对广州番禺大气成分站(GPACS)的历史观测数据进行分析,结果表明在P1(2011-09-02~2011-09-05)和P2(2012-06-12~2012-06-15)期间发生典型灰霾过程并伴有高臭氧(O_3)值事件的发生.在P1和P2复合污染过程中,日能见度变化范围分别为5.78~6.91 km和5.60~9.25 km,最大8 h O_3体积分数分别为92.14×10~(-9)和91.29×10~(-9).在检测到的55种挥发性有机物(VOCs)中,烯烃和芳香烃的活性最高,对等效丙烯浓度和最大O_3体积分数的贡献分别为41%、39%,28%、54%(P1过程)和35%、46%,22%、61%(P2过程).利用气溶胶生成系数(FAC)估算污染过程的二次有机气溶胶(SOA)的生成潜势,发现烷烃、烯烃、芳香烃对SOA的生成潜势分别占13.2%、21.4%、65.4%(P1过程)和4.6%、13.8%、81.6%(P2过程).甲苯、异戊二烯、乙苯、间/对二甲苯是对O_3与SOA生成贡献大的物种.污染物从城区的输送、持续静小风、高温低湿以及强烈辐射共同导致这两次灰霾过程中高臭氧浓度事件的形成.     

Thermodynamic features of the atmospheric boundary layer during the summer monsoon

Characteristic variations in the thermodynamic parameters of the boundary layer at Pune (18°32′N, 73°51′E, 559m a.s.l.) have been studied using the aerological observations collected during the summer monsoon seasons of 1980 and 1981, and the temperature observations from aircraft during the summer monsoons of 1976, 1979–1981. This study showed suppression of the mixed layer, absence of inversion/stable layers and decreased convective instability in the lower layers during the period of active monsoon conditions. The reverse was observed during the periods of weak/break monsoon conditions. Temperature stratification of sub-cloud layer has been classified into four different categories depending on the extent of the mixed layer and the gradient of potential temperature in the overlying stable layer. It was observed that these categories cover all types of weather, conditions which prevailed during the monsoon season. The results are discussed with the possible association of the weather conditions prevailed during the active and break monsoon periods.     

Observational evidence of ozone depletion by nitric oxide at 40 km downwind of a medium size city

Measurements of ozone, oxides of nitrogen, wind and net radiation were made at two sites located about 40 km downwind of the city of calgary which has a population about 625,000. Calgary is located in southern Alberta, Canada, at latitude 51°06′N.Differences in ozone concentrations between the two sites usually showed evidence of depletion through nitric oxide scavenging. Mean levels of depletion were, as required by scavenging theory, highly correlated with similar levels of nitrogen dioxide creation. Departures from correlation are largely explainable in terms of mesoscale variations in ozone.Only about 3 per cent of the data showed ozone depletion to be less than that which would have been expected on the basis of nitric oxide scavenging. These data were collected during afternoon periods and might indicate the presence of ozone creation attributable to photochemical reactions. The lack of more evidence for this phenomena appears to be due to the dispersive action of unsable atmospheres which would have rapidly reduced concentrations of NO_x below values needed for measurable ozone creation.     

Simulation of ozone intrusion caused by a tropopause fold and cut-off low

A tropopause fold and cut-off low developed over Europe at the end of April 1982 and enhanced the exchange of air between the stratosphere and troposphere. The episode has been simulated using the EURAD model which has been designed for long-range transport simulation for European conditions. Applying a linear relationship between potential vorticity and ozone, concentration fields of the tracer and their changes due to outflow of ozone-rich air from the stratosphere could be simulated. A considerable decrease of stratospheric ozone was also obtained. This indicates noticeable mixing of tropospheric air with reduced ozone content into the stratosphere during the episode. Strong downward fluxes more than an order of magnitude larger than normal when averaged over the model domain show up around levels close to the tropopause. Obviously, dynamical processes fovern teh ozone budget o the upper troposphere during the vigorous intrusion event. Drastic increases of ozone also occur in the lower troposphere but are probably underestimated since vertical mixing by clouds is not taken into account in the simulation experiments. It is intended to explore the interaction of ozone of stratospheric and tropospheric (anthropogenic) origin in further experiments.     

Relationships between synoptic-scale atmospheric circulation and ozone concentrations in Metropolitan Pittsburgh,Pennsylvania

A synoptic climatology demonstrates the relationships between the atmospheric circulation and surface ozone (O₃) concentrations. To deduce these associations, a subjective synoptic classification scheme is applied to 10 years' O₃ data from the Pittsburgh metropolitan area. The results focus on four aspects of the atmospheric circulation-O₃ relationship: average, extreme-event, between season and year-to year conditions. On average, each of the nine circulation types is related to a characteristic O₃ concentration level and cumulative O₃ dose. Extreme high-O₃ events are associated with either the western side of a slowly migrating anticyclone or a stagnating extended high-pressure ridge; low-O₃ events are experienced under cool and cloudy cyclonic conditions. Between-season variations in the average and extreme circulation-O₃ relationshipsare observed: the high-pressure features that produce the high st O₃ levels in summer are related to low levels in winter, while circulation patterns that contribute very little to summertime O₃ build-up are associated with the highest levels of wintertime O₃. The latter situation could be caused by tropopause folding and the introduction of stratospheric ozone in winter months. While zonal (meridional) circulation regimes tend to produce lower (higher) mean annual O₃ levels, such year-to-year changes in synoptic-type frequencies do not appear to be strongly related to interannual variations in O₃, and other non-climatic factors appear to be of greater importance.     

我国北方两地环境臭氧浓度对矮菜豆生长的影响

地表臭氧对植物具有显著毒害作用,矮菜豆(Phaseolus vulgaris L.)已被证实对臭氧非常敏感.选用对臭氧敏感性不同的矮菜豆(R123,臭氧耐受性及S156,臭氧敏感性)分别在3个地点(北京昌平、北京生态中心、哈尔滨市)进行室外直接暴露实验,旨在探讨当前环境臭氧浓度对矮菜豆生长的影响.结果表明,生态中心和昌平两地菜豆在当前臭氧浓度下叶片都出现严重臭氧损伤症状,整个生长季S156型菜豆平均臭氧损伤比例比R123型菜豆高23.5%;臭氧损伤自开花期开始,开花期至结荚期损伤加剧,在豆荚成熟期臭氧损伤比例达到最大值.豆荚产量对比发现,昌平和生态中心两地S156型与R123型豆荚产量比值分别为0.48和0.24,哈尔滨地区为0.73,二者比值为1视为生长不受臭氧影响.可见,北京地区较高的环境臭氧浓度已使敏感性作物矮菜豆显著减产.     

我国地级及以上城市臭氧污染来源及控制区划分

为划分我国臭氧污染控制区,制定更加科学合理的臭氧污染控制措施,根据2018年地面臭氧浓度监测数据,分析了全国338个地级及以上城市的臭氧超标情况,利用TCEQ方法计算出各城市的本地生成O₃量与区域传输O₃量,对本地生成O₃量与O₃日最大8 h平均值进行相关性分析,根据决定系数（R²）确定了各城市臭氧污染的主要来源.结果表明,2018年全国共有121个城市O₃浓度超标,超标率达35.8%;104个城市本地生成O₃对当地O₃污染影响较大,是O₃污染的主要来源;另外234个城市O₃污染的主要来源则以区域传输O₃为主.利用城市O₃超标情况与O₃污染来源将城市分为4类：超标-以本地生成O₃为主的城市（N-L）、超标-以区域传输O₃为主的城市（N-T）、达标-以本地生成O₃为主的城市（S-L）和达标-以区域传输O₃为主的城市（S-T）.最终根据各个省份中4类城市的占比,将全国划分为3类控制区：重度控制区、中度控制区及一般控制区.重度控制区中的N-L城市在3类控制区中占比最多（20.3%）,污染最为严重;中度控制区中4类城市的占比均属于中等水平;一般控制区中S-T城市占比最多（65.4%）,污染程度较轻.     

Applying model simulation and photochemical indicators to evaluate ozone sensitivity in southern Taiwan

Ozone sensitivity was investigated using CAMx simulations and photochemical indicator ratios at three sites (Pingtung City, Chao- Chou Town, and Kenting Town) in Pingtung County in southern Taiwan during 2003 and 2004. The CAMx simulations compared fairly well with the hourly concentrations of ozone. Simulation results also showed that Pingtung City was mainly a volatile organic compounds (VOC)-sensitive regime, while Chao-Chou Town was either a VOC-sensitive or a NOx-sensitive regime, depending on the seasons. Measurements of three photochemical indicators (H2O2, HNO3, and NOy) were conducted, and simulated three transition ranges of H2O2/HNO3 (0.5–0.8), O3/HNO3 (10.3–16.2) and O3/NOy (5.7–10.8) were adopted to assess the ozone sensitive regime at the three sites. The results indicated that the three transition ranges yield consistent results with CAMx simulations at most times at Pingtung City. However, both VOC-sensitive and NOx-sensitive regimes were important at the rural site Chao-Chou Town. Kenting Town, a touring site at the southern end of Taiwan, was predominated by a NOx-sensitive regime in four seasons.     

冬小麦田O3气孔与非气孔沉降及风险评估

为了深入了解农田生态系统的O_3干沉降过程,并基于O_3通量(尤其是气孔O_3累积通量)指标进行风险评估,利用涡度相关系统对冬小麦田的O_3干沉降过程进行了连续动态观测,初步分析O_3浓度和总O_3通量的变化过程,着重探析气孔O_3沉降和非气孔O_3沉降的变化特征及其与主要气象因子的关系,并基于剂量指标(AOT40)和通量指标(DF_s06)分别推算出冬小麦的产量损失率.结果表明,观测期间(自2016年3月16日至5月30日)日平均O_3浓度(cO_3)为32.9 n L·L-1;白天(08:00~18:00)和夜间平均总O_3通量(F_(O3))分别为-7.6 nmol·(m~2·s)~(-1)和-3.1 nmol·(m~2·s)~(-1),日均F_(O3)为-5.1nmol·(m~2·s)~(-1).逐日平均气孔O_3通量(F_s)的变化范围为0~-5.1 nmol·(m~2·s)~(-1),日均F_s为-1.43 nmol·(m~2·s)~(-1).逐日平均非气孔O_3通量(F_(ns))的变化范围为-1.43~-10.31 nmol·(m~2·s)~(-1),日均F_(ns)为-3.66 nmol·(m~2·s)~(-1).较强的太阳辐射(SR)、较高的温度(T)和适度湿润的条件有利于冬小麦气孔沉降;较强的SR、适度的T和湿润条件是有利于冬小麦非气孔沉降.在整个观测期间,总O_3累积吸收通量(DF_(O3))、气孔O_3累积吸收通量(DF_s)和非气孔O_3累积吸收通量(DF_(ns))分别为31.58、9.99和21.59 mmol·m~(-2),总DF_s和总DF_(ns)分别占总DF_(O3)的32%和68%.通过剂量指标AOT40和通量指标DF_s06响应方程计算出的冬小麦产量损失率分别为11.58%~20.37%和20%~23.56%.     

Synergistic effects of non-thermal plasma-assisted catalyst and ultrasound on toluene removal

A wire-mesh catalyst coated by La_0.8Sr_0.2MnO₃ was combined with a dielectric barrier discharge (DBD) reactor for toluene removal at atmospheric pressure. It was found that toluene removal efficiency and carbon dioxide selectivity were enhanced in the catalytic packed-bed reactor. In addition, ozone and nitrogen monoxide from the gas effluent byproducts decreased. This is the first time that ultrasound combined with plasma has been used for toluene removal. A synergistic effect on toluene removal was observed in the plasma-assisted ultrasound system. At the same time, the system increased toluene conversion and reduced ozone emission.     

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.     

Diminished effects of El Chichón on stratospheric aerosols,early 1984 to late 1986

Stratospheric aerosol collections by wire impactors, taken mainly over the western United States from early 1984 to late 1986, show the diminishing effects of El Chichón's 1982 eruption, and provide a set of data for judging subsequent volcanic effects (e.g. Pinatubo). Decrease in sulfate burden during the study time is due to preferential gravitational settling-out of large (> 0.5 μm diameter) sulfate aerosol droplets. As a result of settling from higher levels, lower altitude (12.2–15.2 km) air early in 1984 tends to contain more sulfate than higher level (19.8–21.3 km) air. As of late 1986, however, high- and low-altitude sulfate contents have decreased and are similar, suggesting large-particle settling has been completed. The later sulfate collections also have size distributions that in shape resemble unimodal background spectra, whereas earlier ones are bimodal. Average sulfate load for all altitudes decreases during the period of study from 0.4 to 0.08 μg m⁻³. The latter value is somewhat higher than a volcanically unenriched pre-El Chichón level (0.05 μg m⁻³) suggesting that even as of 1987, stratospheric background had not been obtained.     

Real-world fuel efficiency and exhaust emissions of light-duty diesel vehicles and their correlation with road conditions

The real-world fuel efficiency and exhaust emission profiles of CO, HC and NO_x for light-duty diesel vehicles were investigated. Using a portable emissions measurement system, 16 diesel taxies were tested on different roads in Macao and the data were normalized with the vehicle specific power bin method. The 11 Toyota Corolla diesel taxies have very good fuel economy of (5.9 ± 0.6) L/100 km, while other five diesel taxies showed relatively high values at (8.5 ± 1.7) L/100 km due to the variation in transmission systems and emission control strategies. Compared to similar Corolla gasoline models, the diesel cars confirmed an advantage of ca. 20% higher fuel efficiency. HC and CO emissions of all the 16 taxies are quite low, with the average at (0.05 ± 0.02) g/km and (0.38 ± 0.15) g/km, respectively. The average NO_x emission factor of the 11 Corolla taxies is (0.56 ± 0.17) g/km, about three times higher than their gasoline counterparts. Two of the three Hyundai Sonata taxies, configured with exhaust gas recirculation (EGR) + diesel oxidation catalyst (DOC) emission control strategies, indicated significantly higher NO₂ emissions and NO₂/NO_x ratios than other diesel taxies and consequently trigger a concern of possibly adverse impacts on ozone pollution in urban areas with this technology combination. A clear and similar pattern for fuel consumption and for each of the three gaseous pollutant emissions with various road conditions was identified. To save energy and mitigate CO₂ emissions as well as other gaseous pollutant emissions in urban area, traffic planning also needs improvement.