Effect of increasing CO2 on the stratospheric level of CO and O3

Production and destruction processes of carbon monoxide (CO) and ozone (O3) are examined in the light of increasing amount of atmospheric carbon dioxide (CO2). It is found that doubling of CO2 will increase the stratospheric concentration of CO and will have positive effect on O3 concentration.     

蔗糖生产最佳榨期和高糖期的预报

分析广西１３家糖厂历年实际榨期和榨季蔗糖分资料可知，有大部年份的榨期安排不够合理，从而降低了糖厂的经济效益。针对榨期安排的问题，作者从分析蔗糖分积累动态变化入手，将其分类进行模拟，建立模型。     

Distributions of O3, CO and NMHCs over the rural sites in central India

The surface level measurements of O₃, CO, CH₄ and light NMHCs were made at eight different rural sites in the central part of India during February, 2004. The online analyzer was used for in-situ measurement of O₃ while air samples were collected for the analyses of CO, CH₄ and NMHCs using the gas chromatography techniques. The average mixing ratios of O₃, which were in the range of 60–90 ppbv, are significantly higher compared to the typical values reported for urban sites of India. The increase rates of O₃ in the forenoon hours were estimated to be in the range of about 8.8–10 ppbv h⁻¹. The slopes of ∆O₃/∆CO, which is an indicator of the efficiency of photochemical production, were in the range of 0.24–0.33 ppbv ppbv⁻¹. However, levels of primary pollutants e.g., NMHCs, CO, etc. at these sites were much lower than urban sites, but higher compared to previously observed values surrounding marine region of India. The estimated ratios of NMHCs and CO indicate fossil fuel combustion process as the dominant source of primary pollutants in this corridor.     

CO2和O3浓度倍增及其交互作用对大豆影响的试验研究

以大豆“中黄-14”为试验材料, 利用OTC-1型农田开顶式气室, 首次模拟研究单独CO₂和O₃浓度倍增及其交互作用对大豆生物量、产量及其构成因子、同化产物分配形式和收获指数的影响。与未通CO₂和O₃的处理相比, 单独CO₂浓度倍增对生物量、产量、荚果串数、荚数、籽粒数、籽粒重具有正效应, O₃为明显的负效应, 通气时段越长效果越明显; 持续的CO₂浓度和O₃浓度倍增交互作用表现为CO₂的影响大于O₃; CO₂和O₃交互作用逐渐达到浓度倍增的处理, 由于O₃剂量逐渐累积和阶段性增加, 对大豆刺激逐渐增强, 最终O₃的负效应与CO₂的正效应相近。单独O₃浓度倍增抑制光合产物向根和籽粒的输送, 向叶茎的输送明显增强, 使根冠比 (RSR)、子粒与茎杆比 (GCR) 明显下降, 长期作用可使大豆收获指数 (HI) 减小, 叶重比 (LWR) 显著增加, 且随通气时间的延长影响增大; CO₂浓度倍增及其交互作用对RSR、LWR、GCR和HI影响相对较小, 仅在±10%左右。     

Methane,carbon monoxide and light non-methane hydrocarbon emissions from African savanna burnings during the FOS/DECAFE experiment

Atmospheric samples from savanna burnings were collected in the Ivory Coast during two campaigns in January 1989 and January 1991. About 30 nonmethane hydrocarbons from C₂ to C₆, carbon monoxide, carbon dioxide and methane were measured from the background and also at various distances from the burning. Concentrations in the fire plume reached ppmv levels for C₂-C₄ hydrocarbons, and 5300, 500 and 93 ppmv for CO₂, CO and CH₄ respectively. The excess in the mixing ratios of these gases above their background level is used to derive emission factors relative to CO and CO₂. For the samples collected immediately in the fire plume, a differentiation between high and low combustion efficiency conditions is made by considering the CO/CO₂ ratio. Ethene (C₂H₄), acetylene (C₂H₂), ethane (C₂H₆) and propene (C₃H₆) are the major NMHC produced in the flaming stage, whereas a different pattern with an increasing contribution of alkanes is observed in samples typical of post flaming processes. A strong correlation between methane and carbon monoxide suggests that these compounds are produced during the same stage of the combustion. In samples collected at a distance from the fire and integrated over a period of 30 minutes, the composition is very similar to that of flaming. NMHC/CO₂ is of the order of 0.7%, CH₄/CO₂ of the order of 0.4% and CO/CO₂ of the order of 6.3%. From this study, a global production by African savanna fires is derived: 65 Tg of CO-C, 4.2 Tg of CH₄-C and 6.7 Tg of NMHC-C. Whereas acetylene can be used as a conservative tracer of the fire plumes, only ethene, propene and butenes can be considered in terms of their direct photochemical impact.     

热带深对流云对CO、NO、NOx和O3的垂直输送作用

利用2005年11月至2006年2月ACTIVE (Aerosol and Chemical Transport in tropIcal conVEction) 外场试验期间在澳大利亚北部达尔文地区取得的CO、O3、NO和NOx飞机探测资料, 并结合HYSPLIT后向轨迹模式结果, 分析这几种气体成分在对流卷云砧内外的分布情况, 并探讨热带深对流云对于污染气体的垂直输送作用。分析结果显示, 在孤立对流云卷云砧中, 云砧内部O3、NO、NOx浓度均大于云外; 而CO则不同, 只有在近地面浓度高时才如此, 在近地面浓度较小时, 卷云砧内部的浓度反而小于云外。进一步分析造成这两类气体分布差异的原因, 发现CO主要借助深对流云将对流层下层以及对流云周围环境中的CO夹卷并动力垂直输送到对流云顶部卷云砧中, 而对于O3、NO和NOx来说, 除了上述作用以外, 还可能与对流云内部其他物理机制(如闪电), 造成新的O3、NO和NOx有关, 这些新生气体随着风暴内部强烈的上升气流被最终输送进云砧中。     

大气中O3和CO2增加对大豆复合影响的试验研究

利用OTC-1型开顶式气室,对大豆"中黄14"进行了长时期不同O3和CO2处理的接触试验,模拟研究CO2和O3浓度倍增及其交互作用对大豆发育期、黄叶率和绿叶率、根瘤、生物量及其分配、产量结构、籽粒品质及叶片膜保护系统的影响,结果表明:单独O3浓度倍增,发育期明显提前;生物量最多可减少近一半,产量最多减产60%以上;粗蛋白含量增加6.2%,粗脂肪含量降低7.6%;叶片脂膜过氧化加剧.单独CO2浓度倍增,开花后发育期有所延迟;对生物量及产量有明显的正效应,成熟时总生物量和籽粒产量分别比T5增加21.0%和20.3%;粗蛋白和粗脂肪含量分别下降3.3%和1.6%;结荚前叶片脂膜过氧化反应减轻.CO2和O3持续倍增和逐渐达到倍增交互作用处理,在生物量、产量方面表现为CO2的影响大于O3,在叶片膜保护系统方面表现为O3的影响大于CO2,粗蛋白含量下降,粗脂肪含量上升,叶片脂质过氧化加剧.熏气处理均可造成:黄叶率上升,绿叶率下降,凋落物增加,且单独O3浓度倍增的处理最明显,通气仅10天黄叶率就高于50%;超氧化物歧化酶活性增强;气孔阻力增加,蒸腾速率下降,且单独CO2浓度倍增的处理最明显,尤其在高湿阴天,气孔阻力和蒸腾速率变化最高分别可达增加234.0%和下降58.5%.     

Consequences of Incomplete Surface Energy Balance Closure for CO2 Fluxes from Open-Path CO2/H2O Infrared Gas Analysers

We present an approach for assessing the impact of systematic biases in measured energy fluxes on CO₂ flux estimates obtained from open-path eddy-covariance systems. In our analysis, we present equations to analyse the propagation of errors through the Webb, Pearman, and Leuning (WPL) algorithm [Quart. J. Roy. Meteorol. Soc. 106, 85–100, 1980] that is widely used to account for density fluctuations on CO₂ flux measurements. Our results suggest that incomplete energy balance closure does not necessarily lead to an underestimation of CO₂ fluxes despite the existence of surface energy imbalance; either an overestimation or underestimation of CO₂ fluxes is possible depending on local atmospheric conditions and measurement errors in the sensible heat, latent heat, and CO₂ fluxes. We use open-path eddy-covariance fluxes measured over a black spruce forest in interior Alaska to explore several energy imbalance scenarios and their consequences for CO₂ fluxes.     

The heterogeneous formation of N2O in air containing NO2, O3 and NH3

In a nighttime system and under relatively dry conditions (about 15 ppm H₂O), the reaction mixture of NO₂, O₃, and NH₃ in purified air turns out to result in the formation of nitrous oxide (N₂O). The experiments were performed in a continuous stirred flow reactor, in the concentration region of 0.02–2 ppm.N₂O is thought to arise through the heterogeneous reaction of gaseous N₂O₅ and absorbed NH₃ at the wall of the reaction vessel % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9sq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9pue9Fve9% Ffc8meGabaqaciGacaGaaeqabaWaaeaaeaaakeaatCvAUfKttLeary% qr1ngBPrgaiuaacqWFOaakcqWFobGtcqWFibasdaWgaaWcbaGae83m% amdabeaakiab-LcaPmaaBaaaleaacqWFHbqyaeqaaOGaey4kaSIaai% ikaiab-5eaonaaBaaaleaacqWFYaGmaeqaaOGae83ta80aaSbaaSqa% aiab-vda1aqabaGccaGGPaWaaSbaaSqaaiaadEgaaeqaaOGaeyOKH4% Qae8Nta40aaSbaaSqaaiab-jdaYaqabaGccqWFpbWtcqGHRaWkcqWF% ibascqWFobGtcqWFpbWtdaWgaaWcbaGae83mamdabeaakiabgUcaRi% ab-HeainaaBaaaleaacqWFYaGmaeqaaOGae83ta8eaaa!59AC!\[(NH_3 )_a + (N_2 O_5 )_g \to N_2 O + HNO_3 + H_2 O\]In principle, there is competition between this reaction and that of adsorbed H₂O with N₂O₅, resulting in the formation of HNO₃. At high water concentrations (RH>75%), no formation of N₂O was found. Although the rate constant of adsorbed NH₃ with gaseous N₂O₅ is much larger than that of the reaction of adsorbed H₂O with gaseous N₂O₅, the significance of the observed N₂O formation for the outside atmosphere is thought to be dependent on the adsorption properties of H₂O and NH₃ on a surface. A number of NH₃ and H₂O adsorption measurements on several materials are discussed.     

中国地区臭氧前体物对地面臭氧的影响

利用GEOS-Chem模式的数值试验结果,研究中国地区NOx和两类VOCs对O3质量浓度分布及其化学机理的影响。研究表明,NOx的减少会使得中国西部O3质量浓度显著降低,但在冬季NOx的减少会使得东北、华北地区O3质量浓度上升。而京津唐地区由于VOCs/NOx比值偏低,不能通过单一减少NOx来控制O3质量浓度。VOCs排放的减少会使得我国东部地区O3质量浓度大幅减少,其中人为VOCs的减少能降低我国东部地面O3质量浓度,而生物VOCs的减少只能在夏秋季有效减少我国东部地区35°N以南区域的地面O3质量浓度。控制地面O3质量浓度时,中国西部主要考虑NOx的减排,东部35°N以北主要考虑AVOCs的减排,而30~35°N应同时考虑AVOCs和BVOCs的减排,在30°N以南的地区,则需要全面考虑NOx和VOCs的减排。     

Production of N2O,CH4, and CO2 from soils in the tropical savanna during the dry season

Emissions of N₂O, CH₄, and CO₂ from soils at two sites in the tropical savanna of central Venezuela were determined during the dry season in February 1987. Measured arithmetic mean fluxes of N₂O, CH₄, and CO₂ from undisturbed soil plots to the atmosphere were 2.5×10⁹, 4.3×10¹⁰, and 3.0×10¹³ molecules cm^-2 s^-1, respectively. These fluxes were not significantly affected by burning the grass layer. Emissions of N₂O increased fourfold after simulated rainfall, suggesting that production of N₂O in savanna soils during the rainy season may be an important source for atmospheric N₂O. The CH₄ flux measurements indicate that these savanna soils were not a sink, but a small source, for atmospheric methane. Fluxes of CO₂ from savanna soils increased ninefold two hours after simulated rainfall, and remained three times higher than normal after 16 hours. More research is needed to clarify the significance of savannas in the global cycles of N₂O, CH₄, CO₂, and other trace gases, especially during the rainy season.     

研究型业务:来自2020年AMS百年年会的3个解读

AMS年会展示的借助AI芯片(TPU)的更有效的模拟、借助统一编码规则(CCPP)研发各种物理过程的"芯片"并方便地耦合成与人体一样复杂的地球系统,再借助护栏式的"纠偏"机制,已然成为未来预报系统的关键节点。这3个解读单独看是发展动态,合力贡献却可能是未来气象预报全流程的变革和新方向。这些新年代出现的一些创新思想,释放出来的新理念和提示的研究型业务的有力抓手,值得我们关注、学习和在实际工作中思考及选择性借鉴。     

EOS/MODIS数据在广西甘蔗种植信息提取及面积估算的应用

通过计算广西区域多时相MODIS-NDVI值,结合GPS选定甘蔗样本训练区多时相NDVI值变化曲线,以及甘蔗生长周期长达8个月至1年以上,蔗糖生产期间甘蔗面积逐渐递减的特性,采用最大似然法提取非样本训练区甘蔗种植信息,最终实现广西区域的甘蔗种植空间分布遥感信息的提取。经对遥感影像图甘蔗连片种植区域、零散点种植区与GPS实地定位调查比较,结果表明广西区域甘蔗种植信息遥感监测与实况相符。在此基础上,对广西区域甘蔗种植面积估算面积进行初步统计,精度达到90%以上。     

Estimated N2O and CO2 Emissions as Influenced by Agricultural Practices in Canada

The Denitrification-Decompostion (DNDC) model was used to estimate the impact of change in management practices on N₂O emissions in seven major soil regions in Canada, for the period 1970 to 2029. Conversion of cultivated land to permanent grassland would result in the greatest reduction in N₂O emissions, particularly in eastern Canada wherethe model estimated about 60% less N₂O emissions for thisconversion. About 33% less N₂O emissions were predicted for a changefrom conventional tillage to no-tillage in western Canada, however, a slight increase in N₂O emissions was predicted for eastern Canada. GreaterN₂O emissions in eastern Canada associated with the adoption of no-tillage were attributed to higher soil moisture causing denitrification, whereas the lower emissions in western Canada were attributed to less decomposition of soil organic matter in no-till versus conventional tilled soil. Elimination of summer fallow in a crop rotation resulted in a 9% decrease in N₂O emissions, with substantial emissions occurringduring the wetter fallow years when N had accumulated. Increasing N-fertilizer application rates by 50% increased average emissions by 32%,while a 50% decrease of N-fertilizer application decreased emissions by16%. In general, a small increase in N₂O emissions was predicted when N-fertilizer was applied in the fall rather than in the spring. Previous research on CO₂ emissions with the CENTURY model (Smith et al.,2001) allowed the quantification of the combined change in N₂O andCO₂ emissions in CO₂ equivalents for a wide range of managementpractices in the seven major soil regions in Canada. The management practices that have the greatest potential to reduce the combined N₂O andCO₂ emissions are conversion from conventional tillage to permanent grassland, reduced tillage, and reduction of summer fallow. The estimated net greenhouse gas (GHG) emission reduction when changing from cultivated land to permanent grassland ranged from 0.97 (Brown Chernozem) to 4.24 MgCO₂ equiv. ha^–1 y^–1 (BlackChernozem) for the seven soil regions examined. When changing from conventional tillage to no-tillage the net GHG emission reduction ranged from 0.33 (Brown Chernozem) to 0.80 Mg CO₂ equiv. ha^–1 y^–1 (Dark GrayLuvisol). Elimination of fallow in the crop rotation lead to an estimated net GHG emission reduction of 0.43 (Brown Chernozem) to 0.80 Mg CO₂ equiv.ha^–1 y^–1 (Dark Brown Chernozem). The addition of 50% more or 50% less N-fertilizer both resulted in slight increases in combined CO₂ and N₂O emissions. There was a tradeoff in GHG flux with greaterN₂O emissions and a comparable increase in carbon storage when 50% more N-fertilizer was added. The results from this work indicate that conversion of cultivated land to grassland, the conversion from conventional tillage to no-tillage, and the reduction of summerallow in crop rotations could substantially increase C sequestration and decrease net GHG emissions. Based on these results a simple scaling-up scenario to derive the possible impacts on Canada's Kyoto commitment has been calculated.     

Variability of seasonal-mean fields arising from intraseasonal variability. Part 3: Application to SH winter and summer circulations

A study has been made, using the National Centers for Environmental Prediction and National Center for Atmospheric Research re-analysis 500 hPa geopotential height data, to determine how intraseasonal variability influences, or can generate, coherent patterns of interannual variability in the extratropical summer and winter Southern Hemisphere atmospheric circulation. In addition, by separating this intraseasonal component of interannual variability, we also consider how slowly varying external forcings and slowly varying (interannual and longer) internal dynamics might influence the interannual variability of the Southern Hemisphere circulation. This slow component of interannual variation is more likely to be potentially predictable. How sea surface temperatures are related to the slow components is also considered. The four dominant intraseasonal modes of interannual variability have horizontal structures similar to those seen in both well-known intraseasonal dynamical modes and statistical modes of intraseasonal variability. In particular, they reflect intraseasonal variability in the high latitudes associated with the Southern Annular Mode, and wavenumber 4 (summer) and wavenumber 3 (winter) patterns associated with south Pacific regions of persistent anomalies and blocking, and possibly variability related to the Madden-Julian Oscillation (MJO). The four dominant slow components of interannual variability, in both seasons, are related to high latitude variability associated with the Southern Annular Mode, El Nino Southern Oscillation (ENSO) variability, and South Pacific Wave variability associated with Indian Ocean SSTs. In both seasons, there are strong linear trends in the first slow mode of high latitude variability and these are shown to be related to similar trends in the Indian Ocean. Once these are taken into account there is no significant sea surface temperature forcing of these high latitude modes. The second and third ENSO related slow modes, in each season, have high correlations with tropical sea surface temperature variability in the Pacific and Indian Oceans, both contemporaneously and at one season lag. The fourth slow mode has a characteristic South Pacific wave structure of either a wavenumber 4 (summer) or wavenumber 3 (winter) pattern, with strongest loadings in the South Pacific sector, and an association simultaneously with a dipole SST temperature gradient in the subtropical Indian Ocean.     

Numerical Simulation Study on the Impacts of Tropospheric O3 and CO2 Concentration Changes on Winter Wheat.Part I: Model Description

Ozone is well documented as the air pollutant most damaging to agricultural crops and other plants.It is reported that tropospheric O3 concentration increases rapidly in recent 20 years. Evaluating and predicting impacts of ozone concentration changes on crops are drawing great attention in the scientific community. In China, main study method about this filed is controlled experiments, for example, Open Top Chambers. But numerical simulation study about impacts of ozone on crops with crop model was developed slowly, what is more, the study about combined impacts of ozone and carbon dioxide has not been reported.The improved agroecosystem model is presented to evaluate simultaneously impacts of tropospheric O3 and CO2 concentration changes on crops in the paper by integrating algorithms about impacts of ozone on photosynthesis with an existing agroecosystem biogeochemical model (named as DNDC). The main physiological processes of crop growth (phenology, leaf area index, photosynthesis, respiration, assimilated allocation and so on) in the former DNDC are kept. The algorithms about impacts of ozone on photosynthesis and winter wheat leaf are added in the modified DNDC model in order to reveal impacts of ozone and carbon dioxide on growth, development, and yield formation of winter wheat by coupling the simulation about impacts of carbon dioxide on photosynthesis of winter wheat which exists in the former DNDC. In the paper, firstly assimilate allocation algorithms and some genetic parameters (such as daily thermal time of every development stage) were modified in order that DNDC can be applicable in North China. Secondly impacts of ozone on crops were simulated with two different methods-one was impacts of ozone on light use efficiency , and the other was direct effects of ozone on leaves photosynthesis. The latter simulated results are closer to experiment measurements through comparing their simulating results. At last the method of direct impacts of ozone on leaf growth is adopted and the coe cients about impacts of ozone on leaf growth and death are ascertained. Effects of climate changes, increasing ozone, and carbon dioxide concentration on agroecosystem are tried to be simulated numerically in the study which is considered to be advanced and credible.     

地基曙暮光光谱观测反演平流层O3和NO2柱含量

用差分光学吸收光谱(DOAS)方法,从曙暮光天顶散射可见光光谱资料反演了北京上空的O3和NO2柱含量,并对反演结果进行了验证和误差分析.斜柱含量的反演采用了线性和非线性最小二乘拟合方法,拟合时考虑了O3、NO2和H2O的吸收、Ring效应和散射的影响;斜柱含量除以空气质量因子转换成垂直柱含量.空气质量因子的计算使用伪球面DISORT辐射传输模式.O3和NO2总量的检验分别用北京的Dobson O3资料和卫星SAGE Ⅱ的NO2廓线资料.反演的O3总量与Dobson O3总量相比偏差小于10%;NO2总量与SAGE Ⅱ的偏差约20%.     

杭州主城区O3与前体物浓度变化特征

利用2004～2006年杭州主城区环境空气监测资料,研究了O_3、NO_2和CO浓度的分布特征和时间变化规律,结果表明,杭州主城区3年的O_3、NO_2、CO的年均浓度都不大,分别为40、60、1400μg·m~(-3).四季中O_3、NO_2和CO浓度相差较大,O_3是夏季高冬季低,NO_2和CO则是秋季较高,夏季较低.O_3、NO_2和CO浓度日变化也很明显,其中O_3是单峰形态,NO_2和CO为双峰形态.不同天气条件下O_3与烃类的关系研究表明,晴天时烃类浓度减少,O_3浓度明显增加;阴天时O_3浓度较低,烃类浓度较高,它们的变化不大.白天和夜晚不同风速时O_3、C_2-C_(12)的浓度变化不同,白天风速增大时C_2-C_(12)浓度减小,O_3浓度增加;晚上无此变化.