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.     

Mechanism of spring high oxidant episode— A meteorological analysis in and around the Hokuriku district,Japan

In order to clarify the mechanism of spring surface level high oxidant episodes, both upper and surface level ozone observations were carried out from April to June 1983. The results were analyzed using aerological data and AMeDAS (Automated Meteorological Data Acquisition System) data.During the observation period, there were 11 days with high oxidant episodes which were defined as when the recorded ozone concentration exceeded 100 ppb at any of five stations. Meteorological conditions under which the surface episodes occurred were examined for three cases when upper level ozone distributions were observed, and the mechanism of the episode were investigated. In this paper, the analysis for one case is explained in detail. For this case: (i) the peak time of oxidant (ozone) concentration at each surface station was controlled by the transition pattern of photochemical oxidant under the local wind system and (ii) the stratospheric air with high concentrations of ozone intruded into the troposphere through the tropopause gap (tropopause folding) behind the cyclone and continued to descend gradually. In the lower troposphere, it descended further due to the influence of topography, and contributed to high surface oxidant episodes. The descent of stratospheric ozone was related to the position of both cyclones and anticyclones. The other two cases had similar upper meteorological conditions but different surface wind systems such as land and sea breeze.     

On the mean daily and seasonal variations of the vertical ozone profiles in the lower troposphere

During the 15 year period that the Zugspitze cable car has operated between the valley (1 km a.s.l.) and Zugspitze peak (3 km a.s.l.) at the northern border of the Bavarian Alps, it has been used for investigating the profiles of meteorological and atmospheric electrical parameters, and Aitken nuclei. This cable railway is rather steep and is suspended mostly far away from the ground. From 1980 to 1982 nearly 2000 ozone profiles were additionalyrecorded. The data collected offer a profound basis in order to study the time variations of the lower tropospheric ozone profile depending on the hour of the day during all the seasons. In this paper the following are reported: the shape and time behaviour of ozone profiles in different seasons depending on the vertical mixing intensity, stratospheric intrusions and the penetration depth of the stratospheric O₃.     

生物质燃烧对东南亚及中国南方对流层臭氧含量影响的模拟研究

利用区域气候和大气化学模式系统,对2000年春季生物质燃烧排放影响东南亚及中国南部地区对流层臭氧含量进行模拟研究.结果表明,春季东南亚和南亚的生物质燃烧不仅影响源区对流层臭氧含量,而且对处于环流下游的中国南部地区也有显著作用;燃烧源区主要影响对流层低层,下游地区则影响对流层中低层.在源区引起的对流层臭氧总浓度增加达2.1×10^-1g/m²,对下游的中国南部地区增加量为9.0～12.0×10^-2g/m²;源区大气低层1000～900hPa的臭氧含量可增加36×10^-9m³/m³ 以上,而在中国南部750～700hPa高度上空的增加达15×10^-9m³/m³.     

臭氧层损耗影响低层大气质量的新认识

近年来有关平流层臭氧损耗影响低层大气质量的研究表明 ,在污染相对轻的地方 ,可以观测到加强的光化学反应过程 ;在污染地区 ,最终的影响与大气中存在的痕量物质间的相互作用有很大关系 ,这些通常会被人为排放带来的影响所掩盖 ;越来越多的证据表明 ,臭氧层损耗与气候变化之间的相互作用是至关重要的涉及全球变化的问题 ,是今后活跃的科学研究领域。     

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.     

基于OMI数据的中国中东部城市近地面臭氧时空分布特征研究

利用OMI卫星反演数据分析了2005—2014年中国中东部地区对流层臭氧变化趋势.结果表明,近10年来对流层臭氧总柱浓度混合比例较稳定,但近地面浓度明显增加,特别是在冬季臭氧上升速度达40%.同时分析了京津冀、长三角、珠三角地区10个重点城市的臭氧数据,发现京津冀地区的臭氧涨幅超过其他两个地区,其中,长三角地区臭氧混合比例最高,而珠三角地区相对较稳定.利用臭氧激光雷达和地面臭氧监测数据对卫星反演结果进行比较显示了较好的一致性,证明使用卫星反演的数据来研究长时间范围内近地层的臭氧变化是一种可行的方法.     

东亚边界层臭氧时空分布的数值模拟研究

利用嵌套网格空气质量预报模式系统(NAQPMS)对2010年东亚地区边界层臭氧(O3)的时空分布进行了数值模拟,并评估了东亚边界层光化学反应的活性.结果表明,NAQPMS模式与观测结果较为一致,站点观测与模拟的日均值(月均值)相关系数达到0.56~0.91,模式能合理再现东亚地区地面O3的时空分布特征.东亚地区冬季边界层O3低值区出现在中国东部;春季O3浓度增加,西北太平洋沿岸地区O3浓度达60μL/m3左右;夏季东亚中纬度35°N附近大陆地区O3由于强烈的光化学反应呈现出一浓度高值带,浓度达60μL/m3以上;秋季东亚大部分地区O3浓度维持在40~45μL/m3左右.夏季中国京津冀和长江三角洲部分地区光化学净生成率已超过30×10-9/d.     

On the meteorological conditions during some strong smoke episodes in Athens

Data of smoke concentrations from two stations in the downtown Athens area, were used to select eight intense air pollution episodes lasting a total of 31 days in the cold months of the period 1984–1987. The onset of these episodes was found to have been associated with a warm air advection from the south-west or with the withdrawal of a cold air mass that had been previously established over Greece. Rawinsonde data indicated that an intense warming below the 850 mb layer also occured during the first day in seven of the eight episodes, denoting the existence of strong subsidence. During 90% of the episode days the maximum 3-hourly resultant wind speed was less than 2.0 m s⁻¹ between 0000 and 1200 LST, while the mean mixing height was less than 500 m in 65% of the days; only on 1 did it exceed 1000 m. Finally, the end of the episodes was found to have been caused in four of the cases by a cooling of the lowest layers of the troposphere produced by the passage of a weak cold front and in three cases by a substantial increase in the wind or the wixing height.     

四川盆地一次污染过程的WRF模式参数化方案最优配置

精准的气象场是空气质量模型的基础,本文对中尺度气象模式WRF(The Weather Research and Forecasting)中微物理过程方案、陆面过程方案、行星边界层方案以及积云参数化方案进行组合,设计了24组参数化方案,对2014年5月初四川盆地内一次空气重污染过程中的气象场进行了模拟,将模拟输出的10 m风速、2 m温度、2 m相对湿度、水汽混合比廓线及位温廓线与研究区内14个气象站及1个探空站的实测数据进行对比.结果表明,Mellor-Yamada-Janjic(MYJ)边界层方案能更好的模拟出盆地内风速的变化趋势,而Yonsei University(YSU)边界层方案模拟的2 m相对湿度效果更优.第16组参数化方案(由WRF Single-Moment 3-class(WSM3)方案,热扩散(SLAB)方案、Mellor-Yamada-Janjic(MYJ)方案及Grell-Devenyi(GD)方案组合)能够较好地模拟盆地近地面风场的水平分布及风速的日变化规律,模拟的温度日变化规律更贴合实际情况,同时能够模拟出边界层内水汽混合比及位温的垂直分布特征,对边界层内逆温层和混合层的模拟也更加贴近实际,尽管该方案对2m相对湿度的模拟并不是最好,但基本能够模拟出四川盆地气象要素的变化特征,因此认为第16组参数化方案(WSM3,SLAB,MYJ及GD)适用于模拟此次重污染过程的气象场.     

臭氧层耗损对对流层大气质量的影响和在中国的响应

平流层臭氧损耗导致透射到近地面的UV-B辐射的增加,加强了低对流层的能量来源,增强了大气氧化性和化学反应性,特别是加快O₃、颗粒物、酸性物质等二次污染物的生成和一些有机污染物的光解,加剧如光化学烟雾、酸沉降等城市和区域性的大气污染,从而改变对流层的大气组成和空气质量.在中国,UV-B的增加会对城市和区域的空气质量、酸雨污染以及青藏高原地区的环境产生重要的影响.      

Modelling the role of nitrogen oxides,hydrocarbons and carbon monoxide in the global formation of tropospheric oxidants

A new zonally averaged two-dimensional chemical and transport model of the lower atmosphere has been used to study the budgets of photochemical oxidants on a global scale in the troposphere. The sensitivities of these budgets to controls on the emissions of NO_x, CO and hydrocarbons from a variety of sources have also been considered. The species studied include O₃, PAN, H₂O₂ and organic peroxides, as well as the global budget of the hydroxyl radical. The results show the relative impacts of emissions from natural and from man-made sources. Overall, some 75% of the turnover of tropospheric ozone results from in situ chemical production, with only 25% having its origins in the stratosphere. The respective fractions for chemical loss and dry deposition are similar. Of the ozone formed in situ, approximately one-third is formed from natural emissions, and two-thirds from man-made emissions. Over half of this man-made contribution is due to industrial society, with much of the rest being caused by biomass burning and methane emitted from paddy fields. Although reducing emissions of NO_x is the most effective way of controlling tropospheric O₃, this also increases the inventories of peroxides and the rate of increase in the concentration of methane, due to a reduction in the inventory of the OH radical. It is, therefore, necessary to control the emissions of a wide range of species in order to reduce the budget of all photochemical oxidants without adversely perturbing the budget of CH₄.     

A numerical study of summer ozone concentration over the Kanto area of Japan using the MM5/CMAQ model

We assessed the ability of the MM5/CMAQ model to predict ozone (O3) air quality over the Kanto area and to investigate the factors that a ect simulation of O3. We find that the coupled MM5/CMAQ model is a useful tool for the analysis of urban environmental problems. The simulation results were compared with observational data and were found to accurately replicate most of the important observed characteristics. The initial and boundary conditions were found to have a significant e ect on simulated O3 concentrations. The results show that on hot and dry days with high O3 concentration, the CMAQ model provides a poor simulation of O3 maxima when using initial and boundary conditions derived from the CMAQ default data. The simulation of peak O3 concentrations is improved with the JCAP initial and boundary conditions. On mild days, the default CMAQ initial and boundary conditions provide a more realistic simulation. Meteorological conditions also have a strong impact on the simulated distribution and accumulation of O3 concentrations in this area. Low O3 concentrations are simulated during mild weather conditions, and high concentrations are predicted during hot and dry weather. By investigating the e ects of di erent meteorological conditions on each model process, we find that advection and di usion di er the most between the two meteorological regimes. Thus, di erences in the winds that govern the transport of O3 and its precursors are likely the most important meteorological drivers of ozone concentration over the central Kanto area.     

夏季对流层臭氧辐射强迫对华北地区天气和空气质量的影响

自2013年我国实施《大气污染防治行动计划》以来,大气颗粒物浓度显著降低,但臭氧（O₃）污染日益严峻,同时对流层O₃作为一种重要的温室气体,其辐射强迫能够影响天气和空气质量.利用双向耦合的区域空气质量模型WRF-Chem,再现2017年6月发生在华北地区的一次O₃污染事件,通过敏感性试验分析对流层臭氧辐射强迫（TORF）对当地气象场的影响,以及改变的气象变量对O₃空气质量的反馈作用.结果表明,WRF-Chem模式在气象要素的模拟上表现出较好的性能,并且能够很好地捕捉到O₃浓度的时空演变特征.TORF使北京-天津-河北-山东地区的近地面气温平均升高0.23 K （最大增温可达0.8 K）、近地面相对湿度降低1.84%、边界层高度增加27.73 m.TORF对风速的影响较弱（-0.02 m ·s^-1）,但产生的西南风异常容易将上游污染地区的O₃和其前体物输送至华北地区.在臭氧辐射反馈的影响下,研究区域内φ（O₃）平均增加1.7%（1.23×10^-9）,而在污染严重的北京和天津地区,φ（O₃）增加量最高可达5×10^-9.进一步利用过程诊断分析法可以发现,增强的气相化学反应是TORF恶化近地面O₃污染的主导原因.     

北京地面紫外辐射与空气污染的关系研究

基于北京城区太阳辐射和污染气体观测资料,运用TUV4.4辐射传输模型,研究了城市大气中太阳紫外辐射与空气污染的相互关系.结果表明,臭氧总量平均为329DU,并呈冬春季较高,夏秋季较低的季节变化规律,到达地面的紫外辐射呈现相反的变化趋势;受城区大气污染的影响,地面处的紫外辐射量大幅减少(最大50%),且在夏季波动较大;云和污染物对紫外辐射的影响要大于总辐射,紫外辐射衰减约为总辐射衰减的2倍;城市低层大气中O3和NOx浓度的增加是造成紫外辐射衰减的重要原因,午后O3浓度与紫外辐射衰减相关系数为0.70.     

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。     

A primary study of nitrous oxide emission in agriculture region of Northern China

Significance of nitrous oxide in atmospheric chemistry is reviewed briefly. Background concentration of N2O at Wudaoliang in Qinghai Province of Western China has been measured by collecting gas samples and analysing them with electron capture-gas chromatography. The atmospheric concentration fluctuates in the range of 303-315 ppb with the mean value of 308 ppb. The emission rate of N2O in agriculture region of Northern China has been studied primarily. Fertilization, rain and temperature of soil appear conductible to N2O emission. The interactions between greenhouse effect and N2O emission have been discussed. The catalytic action of N2O in stratospheric ozone depletion processes and the effect of high N2O concentration on ozone depletion in stratosphere have been considered and discussed.     

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.     

区域空气质量模拟中查表法的应用研究

在自行开发完善的区域空气质量模式系统RegSRRMS中应用查表法,模拟中国典型城市群对流层大气主要污染物的浓度变化,评估该方法在大气复合污染事件预测和控制中的有效性.首先,利用具有国际先进水平的空气质量模式WRF-CHEM中的化学模块建立了包含完善气相化学、气溶胶过程的箱模式WRFBOX.其次,利用WRFBOX进行化学反应敏感性分析,基于影响污染物的重要因子分别建立了臭氧(O3)及其前体物、无机盐气溶胶和二次有机气溶胶(SOA)查算表数据库,并检验其有效性.最后,将此查算表数据库引入RegSRRMS,建立简化的查表算法.利用直接耦合机制法和查表法对2000年3月珠三角地区污染个例中主要大气污染物浓度进行模拟.通过比较2种方法的模拟结果,显示查表法计算效率提高了57%,能够反映大气光化学反应的非线性特征、气溶胶及其前体物的平衡关系,具有高分辨率、高时效性,能够方便快捷地给出源和受体之间的响应关系,结果可靠.在区域空气质量模式中应用查表法有利于大气污染事件的快速预测以及大气污染控制的快速决策.     

天津武清大气挥发性有机物光化学污染特征及来源

大气VOCs(挥发性有机物)是臭氧的重要前体物之一,研究其光化学污染特征和来源对控制近地面臭氧污染具有重要意义. 于2006年8月10日—9月18日在天津郊区武清采用在线监测的方法,同步观测了VOCs、O₃和NO₂等气态污染物,以及温度和紫外辐射等气象因子. 对9月10—15日臭氧浓度较高时段VOCs的浓度水平、化学反应活性、臭氧生成潜势和来源进行了分析. 结果表明:天津郊区武清环境空气中VOCs体积混合比平均浓度为24.6×10-9;VOCs主要由烷烃和烯烃组成,机动车排放、轻烃工艺、生物排放、沼气和碳氢溶剂是其重要来源. 根据等效丙烯浓度和MIR方法评估,烯烃对臭氧光化学产生的贡献占主导性地位,其中异戊二烯、丙烯、二甲苯和甲苯是臭氧生成潜势较大的物种. 通过与天津城区比较发现,郊区与城区的大气VOCs不仅组成不同,而且化学活性物种也不同.