Relative radiative forcing consequences of global emissions of hydrocarbons, carbon monoxide and NOx from human activities estimated with a zonally-averaged two-dimensional model

A global two-dimensional (altitude-latitude) chemistry transport model is used to follow the changes in the tropospheric distribution of the two major radiatively active trace gases, methane and ozone, following step changes to the sustained emissions of the short-lived trace gases methane, carbon monoxide and non-methane hydrocarbons. The radiative impacts were dependent on the latitude chosen for the applied change in emissions. Step change global warming potentials (GWPs) were derived for a range of short-lived trace gases to describe their time-integrated radiative forcing impacts for unit emissions relative to that of carbon dioxide. The GWPs show that the tropospheric chemistry of the hydrocarbons can produce significant indirect radiative impacts through changing the tropospheric distributions of hydroxyl radicals, methane and ozone. For aircraft, the indirect radiative forcing impact of the NO _x emissions appears to be greater than that from their carbon dioxide emissions. Quantitative results from this two-dimensional model study must, however, be viewed against the known inadequacies of zonally-averaged models and their poor representation of many important tropospheric processes.     

Transient Behaviour of Tropospheric Ozone Precursors in a Global 3-D CTM and Their Indirect Greenhouse Effects

The global three-dimensional Lagrangian chemistry-transport model STOCHEM has been used to follow the changes in the tropospheric distributions of the two major radiatively-active trace gases, methane and tropospheric ozone, following the emission of pulses of the short-lived tropospheric ozone precursor species, methane, carbon monoxide, NO_x and hydrogen. The radiative impacts of NO_x emissionswere dependent on the location chosen for the emission pulse, whether at the surface or in the upper troposphere or whether in the northern or southern hemispheres. Global warming potentials were derived for each of the short-lived tropospheric ozone precursor species by integrating the methane and tropospheric ozone responses over a 100 year time horizon. Indirect radiative forcing due to methane and tropospheric ozone changes appear to be significant for all of the tropospheric ozone precursor species studied. Whereas the radiative forcing from methane changes is likely to be dominated by methane emissions, that from tropospheric ozone changes is controlled by all the tropospheric ozone precursor gases, particularly NO_xemissions. The indirect radiative forcing impacts of tropospheric ozone changes may be large enough such that ozone precursors should be considered in the basket of trace gases through which policy-makers aim to combat global climate change.     

利用卫星资料分析对流层臭氧柱总量分布特征及其可能的原因

利用卫星资料计算得到的对流层臭氧柱总量数据分析了近20年来全球对流层臭氧柱总量的全球分布特征，并对我国对流层臭氧的季节变化做了研究。利用对流层污染测量仪（MOPITT）的CO和全球臭氧监测仪（GOME）和大气制图扫描成像吸收光谱仪（SCIAMACHY）的NO₂数据分析了关于对流层臭氧的分布特征及其原因。得出中高纬度地区对流层臭氧浓度存在规律的年内变化，对流层臭氧高浓度值的分布及变化与人类活动有密切关切。     

A numerical study of tropospheric ozone in the springtime in East Asia

The Models-3 Community Multi-scale Air Quality modeling system (CMAQ)coupled with the Regional Atmospheric Modeling System (RAMS)is applied to East Asia to study the transport and photochemical transformation of tropospheric ozone in March 1998．The calculated mixing ratios of ozone and carbon monoxide are compared with ground 1evel observations at three remote sites in Japan and it is found that the model reproduces the observed features very well．Examination of several high episodes of ozone and carbon monoxide indicates that these elevated levels are found in association with continental outflow,demonstrating the critical role of the rapid transport of carbon monoxide and other ozone precursors from the continental boundary layer．In comparison with available ozonesonde data,it is found that the model-calculated ozone concentrations are generally in good agreement with the measurements,and the stratospheric contribution to surface ozone mixing ratios is quite limited．     

Impacts of Global Emissions of CO, NOx, and CH4 on China Tropospheric Hydroxyl Free Radicals

Using the global chemistry and transport model MOZART,the simulated distributions of tropospheric hydroxyl free radicals(OH) over China and its sensitivities to global emissions of carbon monoxide(CO),nitrogen oxide(NO x),and methane(CH 4) were investigated in this study.Due to various distributions of OH sources and sinks,the concentrations of tropospheric OH in east China are much greater than in west China.The contribution of NO + perhydroxyl radical(HO 2) reaction to OH production in east China is more pronounced than that in west China,and because of the higher reaction activity of non-methane volatile organic compounds(NMVOCs),the contributions to OH loss by NMVOCs exceed those of CO and take the dominant position in summer.The results of the sensitivity runs show a significant increase of tropospheric OH in east China from 1990 to 2000,and the trend continues.The positive effect of double emissions of NO x on OH is partly offset by the contrary effect of increased CO and CH 4 emissions:the double emissions of NO x will cause an increase of OH of 18.1%-30.1%,while the increases of CO and CH 4 will cause a decrease of OH of 12.2%-20.8% and 0.3%-3.0%,respectively.In turn,the lifetimes of CH 4,CO,and NO x will increase by 0.3%-3.1% with regard to double emissions of CH 4,13.9%-26.3% to double emissions of CO and decrease by 15.3%-23.2% to double emissions of NO x.     

人类活动对气候影响的研究Ⅰ.温室气体和气溶胶

近5年来中国在温室气体源和汇,碳循环,气溶胶以及对流层臭氧等方面都进行了大量的研究.作者着重介绍农田温室气体排放,碳循环模式,亚洲沙尘气溶胶,对流层臭氧前体物的来源以及大气有机化合物的浓度观测等方面的主要研究成果,特别是关于稻田甲烷排放和沙尘气溶胶的物理化学特性方面的研究成果.     

A review of research on human activity induced climate change I. Greenhouse gases and aerosols

Extensive research on the sources and sinks of greenhouse gases, carbon cycle modeling, and the characterization of atmospheric aerosols has been carried out in China during the last 10 years or so. This paper presents the major achievements in the fields of emissions of greenhouse gases from agricultural lands,carbon cycle modeling, the characterization of Asian mineral dust, source identification of the precursors of the tropospheric ozone, and observations of the concentrations of atmospheric organic compounds.Special, more detailed information on the emissions of methane from rice fields and the physical and chemical characteristics of mineral aerosols are Dresented.     

A Review of Research on Human Activity Induced Climate ChangeⅠ. Greenhouse Gases and Aerosols

Extensive research on the sources and sinks of greenhouse gases, carbon cycle modeling, and the characterization of atmospheric aerosols has been carried out in China during the last 10 years or so. This paper presents the major achievements in the fields of emissions of greenhouse gases from agricultural lands, carbon cycle modeling, the characterization of Asian mineral dust, source identification of the precursors of the tropospheric ozone, and observations of the concentrations of atmospheric organic compounds. Special, more detailed Information on the emissions of methane from rice fields and the physical and chemical characteristics of mineral aerosols are presented.     

Tropospheric Ozone in a Global-Scale Three-Dimensional Lagrangian Model and Its Response to NOX Emission Controls

A three-dimensional Lagrangian tropospheric chemistry modelis used toinvestigate the impact of human activities on the tropospheric distributionofozone and hydroxyl radicals. The model describes the behaviour of 50 speciesincluding methane, carbon monoxide, oxides of nitrogen, sulphur dioxide andnineorganic compounds emitted from human activities and a range of other sources.Thechemical mechanism involves about 100 chemical reactions of which 16 arephotochemical reactions whose diurnal dependence is treated in full. The modelutilises a five minute chemistry time step and a three hour advection timestepfor the 50,000 air parcels. Meteorological data for the winds, temperatures,clouds and so on are taken from the UK Meteorological Office global model for1994 onwards. The impacts of a 50% reduction in European NO_Xemissions onglobal ozone concentrations are assessed. Surface ozoneconcentrations decrease in summertime and rise in wintertime, but to differentextents.     

Characterization of carbon monoxide,methane and nonmethane hydrocarbons in emerging cities of Saudi Arabia and Pakistan and in Singapore

We investigate the composition of 63 C₂-C₁₀ nonmethane hydrocarbons (NMHCs), methane (CH₄) and carbon monoxide (CO), in Jeddah, Mecca, and Madina (Saudi Arabia), in Lahore, (Pakistan), and in Singapore. We established a database with which to compare and contrast NMHCs in regions where ambient levels and emissions are poorly characterized, but where conditions are favorable to the formation of tropospheric ozone, and where measurements are essential for improving emission inventories and modeling. This dataset will also serve as a base for further analysis of air pollution in Western Saudi Arabia including, but not limited to, the estimation of urban emissions and long range pollution transport from these regions. The measured species showed enhanced levels in all Saudi Arabian cities compared to the local background but were generally much lower than in Lahore. In Madina, vehicle exhaust was the dominant NMHC source, as indicated by enhanced levels of combustion products and by the good correlation between NMHCs and CO, while in Jeddah and Mecca a combination of sources needs to be considered. Very high NMHC levels were measured in Lahore, and elevated levels of CH₄ in Lahore were attributed to natural gas. When we compared our results with 2010 emissions from the MACCity global inventory, we found discrepancies in the relative contribution of NMHCs between the measurements and the inventory. In all cities, alkenes (especially ethene and propene) dominated the hydroxyl radical (OH) reactivity (k _OH) because of their great abundance and their relatively fast reaction rates with OH.     

The photochemistry of synoptic-scale ozone synthesis: Implications for the global tropospheric ozone budget

The oxidation of nonmethane hydrocarbons represents a source of tropospheric ozone that is primarily confined to the boundary layers of several highly industrialized regions. (Each region has an area greater than one million km²). Using a photochemical model, the global tropospheric ozone budget is reexamined by including the in-situ production from these localized regimes. The results from these calculations suggest that the net source due to this photochemistry, which takes place on the synoptic scale, is approximately as large as the amount calculated for global scale photochemical processes which consider only the oxidation of methane and carbon monoxide. Such a finding may have a considerable impact on our understanding of the tropospheric ozone budget. The model results for ozone show reasonable agreement with the climatological summer distribution of ozone and the oxides of nitrogen at the surface and with the vertical distribution of ozone and nonmethane hydrocarbons obtained during a 1980 field program.     

Model analysis of seasonal variations in tropospheric ozone and carbon monoxide over East Asia

Temporal-spatial variations in tropospheric ozone concentrations over East Asia in the period from 1 January 2000 to 31 December 2004 were simulated by using the Models-3 Community Multi-scale Air Quality (CMAQ) modeling system with meteorological fields calculated by the Regional Atmospheric Modeling System (RAMS). The simulated concentrations of ozone and carbon monoxide were compared with ground level observations at two remote sites, Ryori (39.03°N, 141.82°E) and Yonagunijima (24.47°N, 123.02°E). The co...     

Responses of the tropospheric ozone and odd hydrogen radicals to column ozone change

The response of tropospheric ozone to a change in solar UV penetration due to perturbation on column ozone depends critically on the tropospheric NO _x (NO+NO₂) concentration. At high NO _x or a polluted area where there is net ozone production, a decrease in column ozone will increase the solar UV penetration to the troposphere and thus increase the tropospheric ozone concentration. However, the opposite will occur, for example, at a remote oceanic area where NO _x is so low that there is net ozone destruction. This finding may have important implication on the interpretation of the long term trend of tropospheric ozone. A change in column ozone will also induce change in tropospheric OH, HO₂, and H₂O₂ concentrations which are major oxidants in the troposphere. Thus, the oxidation capacity and, in turn, the abundances of many reduced gases will be perturbed. Our model calculations show that the change in OH, HO₂, and H₂O₂ concentrations are essentially independent of the NO _x concentration.     

A model investigation of the impact of increases in anthropogenic NO x emissions between 1967 and 1980 on tropospheric ozone

Recent observations suggest that the abundance of ozone between 2 and 8 km in the Northern Hemisphere mid-latitudes has increased by about 12% during the period from 1970 to 1981. Earlier estimates were somewhat more conservative suggesting increases at the rate of 7% per decade since the start of regular observations in 1967. Previous photochemical model studies have indicated that tropospheric ozone concentrations would increase with increases in emissions of CO, CH₄ and NO _x . This paper presents an analysis of tropospheric ozone which suggests that a significant portion of its increase may be attributed to the increase in global anthropogenic NO _x emissions during this period while the contribution of CH₄ to the increase is quite small. Two statistical models are presented for estimating annual global anthropogenic emissions of NO _x and are used to derive the trend in the emissions for the years 1966–1980. These show steady increase in the emissions during this interval except for brief periods of leveling off after 1973 and 1978. The impact of this increase in emissions on ozone is estimated by calculations with a onedimensional (latitudinal) model which includes coupled tropospheric photochemistry and diffusive meridional transport. Steady-state photochemical calculations with prescribed NO _x emissions appropriate for 1966 and 1980 indicate an ozone increase of 8–11% in the Northern Hemisphere, a result which is compatible with the rise in ozone suggested by the observations.     

大气甲烷浓度长期变化及未来趋势

应用初步建立的全球二维大气化学模式,对工业革命以来甲烷的长期变化进行了模拟研究。模式将CH4、CO和NOx排放源方案进行了参数化。在考虑了CH4排放源以及对OH浓度有重要影响的CO和NOx排放源的长期变化的基础上,模拟了CH4和OH浓度自1840年到20世纪90年代的长期变化趋势。结果表明,工业革命前的大气甲烷体积分数和年排放总量分别为760×10-9和280Tg,1991年大气甲烷的体积分数和年排放总量分别为1611.9×10-9和533.9Tg。而对流层中OH的数密度则由1840年的7.17×105cm-3变化到1991年的5.79×105cm-3,下降了19%。如果CH4、CO及NOx这三种排放源继续按给定的方案增长,那么到2020年大气甲烷的体积分数和年排放总量将增加为2090.7×10-9和966.2Tg,而OH的数密度将为5.47×105cm-3,比1840年降低24%。     

强对流天气对O3和CO的垂直输送作用

利用ACTIVE（aerosol and chemical transport in tropical convection）试验资料,取2006年1月20日澳大利亚北部达尔文岛附近发生的一次飑线强对流天气的AE17航次和2006年1月27日无对流天气的AE21航次飞行路径中的探测资料,对澳大利亚达尔文地区夏季风盛行期间发生的有无强对流发生时O₃和CO浓度垂直分布变化进行对比,考察强对流性天气发生对O₃和CO浓度垂直输送作用。深对流云内强烈的垂直上升运动将O₃和CO等化学气体携带输送至对流层上部并在对流层顶堆积,从而在对流层上部产生浓度峰值。当有强对流发生,飞机进入对流云上层时,O₃浓度和CO浓度升高,O₃和CO浓度变率增大,在对流层上部浓度出现峰值;当飞机飞出对流云时,O₃和CO浓度相对较低,在对流云外出现谷值。在无对流发生的条件下O₃和CO浓度相对较小,浓度变率也较小,无峰值产生。分析表明:O₃和CO浓度分布不仅与强对流的垂直输送作用关系密切,且与气象要素垂直和水平分布以及动力输送过程密切相关。     

Emission scenarios for a global hydrogen economy and the consequences for global air pollution

Hydrogen is named as possible energy carrier for future energy systems. However, the impact of large-scale hydrogen use on the atmosphere is uncertain. Application of hydrogen in clean fuel cells reduces emissions of air pollutants, but emissions from hydrogen production and leakages of molecular hydrogen could influence atmospheric chemistry. This paper combines a global energy system model and a global atmospheric model to explore the range of impacts of hydrogen on atmospheric chemistry. We found that emissions of molecular hydrogen may range from 0.2 up to 10% (or 25-167 Tg hydrogen/yr) for a global hydrogen energy system. The lower end of this range would in fact be equal to current emissions from fossil fuel combustion. Hydrogen energy use leads to a clear decrease in emissions of carbon monoxide, nitrogen oxides and sulphur dioxide, but large-scale hydrogen production from coal may lead to net increase in emissions of nitrous oxide and volatile organic compound. Compared to a reference scenario, this would lead to positive impacts on surface concentrations of carbon monoxide, nitrogen oxides and ozone. However, if hydrogen leakage would not be minimised it leads to an increase in methane lifetimes and a decrease in stratospheric ozone concentrations.     

Correlation between black carbon aerosols, carbon monoxide and tropospheric ozone over a tropical urban site

Black carbon aerosols plays an important role in the earth's radiative balance and little is known of their concentrations, distributions, source strength, and especially the aerosol chemistry of the developing world. The present study addresses the impact of back carbon aerosols on different atmospheric species like CO and tropospheric ozone over an urban environment, namely Hyderabad, India. Ozone concentration varies from 14 to 63 ppbv over the study area. Diurnal variations of ozone suggest that ozone concentration starts increasing gradually after sunrise, attaining a maximum value by evening time and decreasing gradually thereafter. Black carbon (BC) aerosol mass concentrations varies from 1471 to 11,175 ng m⁻³. The diurnal variations of BC suggest that the concentrations are increased by a factor of 2 during morning (06:00–09:00 h) and evening hours (18:00 to 22:00 h) compared to afternoon hours. Positive correlation has been observed between BC and CO (r²=0.74) with an average slope of 6.4×10⁻³ g BC/g CO. The slope between black carbon aerosol mass concentration and tropospheric ozone suggests that every 1 μg m⁻³ increase in black carbon aerosol mass concentration causes a 3.5 μg m⁻³ reduction in tropospheric ozone. The results have been discussed in detail in the paper.     

Impact of future climatic changes on high ozone levels in European suburban areas

The gradual increase in temperature is one of the most pronounced trends of climatic changes in the atmosphere. The pollution levels depend essentially on the emissions (both on the human-made emissions and on the biogenic emissions) as well as on the chemical reactions which take place during the transport of pollutants in the atmosphere. Since both the chemical reactions and the biogenic emissions depend on the temperature, it is obvious that the gradual increase of the temperature will have some effect on pollution levels. The impact of climatic changes on high ozone levels, which may have damaging effects on human health, is studied in this paper. Eight European suburban areas were selected. These areas are densely populated and, therefore, increased ozone pollution levels may cause harm to a great number of human beings living there. All experiments indicate that, although the changes of the ozone concentrations are relatively small, some critical levels, which are related to ozone concentrations and which may have damaging effects, will be significantly exceeded as a result of the warming trend in the future climate.     

Scenarios of possible changes in atmospheric temperatures and ozone concentrations due to man's activities,estimated with a one-dimensional coupled photochemical climate model

A one-dimensional coupled climate and chemistry model has been developed to estimate past and possible future changes in atmospheric temperatures and chemical composition due to human activities. The model takes into account heat flux into the oceans and uses a new tropospheric temperature lapse rate formulation. As found in other studies, we estimate that the combined greenhouse effect of CH₄, O₃, CF₂Cl₂, CFCl₃ and N₂O in the future will be about as large as that of CO₂. Our model calculates an increase in average global surface temperatures by about 0.6°C since the start of the industrial era and predicts for A.D. 2050 a twice as large additional rise. Substantial depletions of ozone in the upper stratosphere by between 25% and 55% are calculated, depending on scenario. Accompanying temperature changes are between 15°C and 25°C. Bromine compounds are found to be important, if no rigid international regulations on CFC emissions are effective. Our model may, however, concivably underestimate possible effects of CFCl₃, CF₂Cl₂, C₂F₃Cl₃ and other CFC and organic bromine emissions on lower stratospheric ozone, because it can not simulate the rapid breakdown of ozone which is now being observed worldwide. An uncertainty study regarding the photochemistry of stratospheric ozone, especially in the region below about 25 km, is included. We propose a reaction, involving excited molecular oxygen formation from ozone photolysis, as a possible solution to the problem of ozone concentrations calculated to be too low above 45 km. We also estimate that tropospheric ozone concentrations have grown strongly in the northern hemisphere since pre-industrial times and that further large increases may take place, especially if global emissions of NO_x from fossil fuel and biomass burning were to continue to increase. Growing NO_x emissions from aircraft may play an important role in ozone concentrations in the upper troposphere and low stratosphere.