Ozone Production Efficiency in Savanna and Forested Areas during the EXPRESSO Experiment     

T. Marion  P. E. Perros  R. Losno  E. Steiner 《Journal of Atmospheric Chemistry》2001,38(1):3-30

NO, NO_x, NO_y and O₃ have been measuredduring the airborne EXPRESSO experiment, November 96,which took place near Bangui (Central Africa) at thebeginning of the dry season. This period correspondsto an intense burning activity. Chemical andphotochemical characteristics of the planetaryboundary layer, which corresponds most of the time tothe monsoon layer, and the Harmattan layer, which issituated above the latter, have been studied forsavanna as well as rain forest areas. These two layersare very different when considering the chemicalcomposition (especially for ozone and NO_z) andthe photochemical age.The relationship of photochemical ozone productionversus photochemical NO_x oxidation products hasbeen investigated. Results indicate an ozoneproduction efficiency (OPE) ranging from 6.3 to 14.8in the planetary boundary layer. Thus, this layer ischaracteristic of a photochemically young and activeair mass. In this layer, the ozone potentialproduction increases with the air mass photochemicalage. On the other hand, the Harmattan layer shows anOPE ranging from 4.6 to 7.4. These values arecharacteristic of photochemically well-aged airmasses. In this layer, the ozone potential productionseems to be exhausted with values around 4.0 (i.e., 4ozone molecules produced for each NO_x moleculeemitted).  相似文献   

Changes to the Surface Level Solar Ultraviolet-B Radiation Due to Haze Perturbation     

Mohammed Ilyas  Arunsala Pandy  Mohd. Suhaimi Jaafar 《Journal of Atmospheric Chemistry》2001,40(2):111-121

The South-East Asian region experienced a haze episode in 1994 which was widely believed to be due to widespread forest fires in Sumatra and Kalimantan (Indonesia). Broadband measurements of the surface level solar ultraviolet-B, UV-A and Global radiation at Penang (Malaysia) are used to study the effect of the 1994 haze on effective UV-B irradiance. We find that during the haze episode, there is enhanced absorption of surface level UV-B radiation. The effect of haze on UV-A and Global radiation is much less. The reduction in absolute noon time UV-B irradiance (mostly cloud free) during the 1994 haze period was 23% relative to the UV-B irradiance during thecorresponding haze-free period in 1995. Even though the noon time radiation data minimizes the cloud effect in the results presented some cloud effect is still present.  相似文献   

MEASUREMENTS AND MODEL SIMULATIONS OF SURFACE OZONE VARIATIONS AT DIFFERENT BACKGROUND CONCENTRATIONS OF THE PRECURSORS   总被引：1，自引：0，他引：1  

罗超  汤洁  周秀骥 《Acta Meteorologica Sinica》1996,(2)

Ozone photochemical production and loss in very different environments at Waliguan baselinestation and Lin'an background station were simulated by using the measurement data and photo-chemical box model.The results show that net ozone photochemical production rate is negative,about 0.5 ppb/d,at Waliguan baseline sation,because of very low precursor concentrations.Butat Lin'an background station,the net photochemical ozone production is positive,about 2—3 ppb/h.which is very closed with the measurement at Lin'an.That means ozone production was con-trolled by photochemical reactions at Lin'an background station,because of the higher precursorconcentrations.The net destruction rate,at Waliguan Mt.,is not large,so that future increase inanthropogenic emission of reactive nitrogen will lead to larger production rates of steady-state O_3concentration.  相似文献   

大气臭氧与气溶胶垂直分布的高空气球探测   总被引：17，自引：2，他引：17  

石广玉  许黎  郭建东  张豹武  孙宝来  龚知本  周军  谭锟  岩坂泰信  林政彦  长谷正博 《大气科学》1996,20(4):401-407

本文给出了1993年9月12日利用高空科学气球在河北省香河地区探测到的大气臭氧和气溶胶的垂直分布。结果发现:(1) 大气臭氧的数密度在整个对流层较低(～10[12]mol/cm3)，并从地面到对流层顶略有下降；对流层顶以上开始快速增加，极值层高度在～24 km，其值为4.78×10[12]mol/cm3；臭氧分压有类似的分布特征，极值146×10[-4]Pa，位于同一高度；(2) 在平流层低层，臭氧分压有一个次极值62×10[-4]Pa，位于15～16 km；(3) 0～30 km大气气溶胶数密度呈现出三个峰值:143，8和1.1 个/cm[3]，分别位于近地面、5 km和21 km；（4）气溶胶的数密度谱在对流层为双模态；在平流层，次峰消失。同时，我们还与其他观测结果作了比较分析。  相似文献   

中层大气行星波在臭氧的季节和年际变化中输运作用的数值研究──Ⅰ．常定流的情况     

陈文  黄荣辉 《大气科学》1996,(5)

本文构造了一个３４层球坐标原始方程波－流相互耦合谱模式，利用此模式从拉格朗日平均环流的观点研究了在常定流下行星波对臭氧的输运作用。研究结果表明，行星波对臭氧的输运有明显的季节变化，在北半球冬季，由于行星波上传到平流层而大大增强了中高纬地区向极地向下的Ｏ３输运；并且还表明，热带纬向风的ＱＢＯ不仅通过影响东、西风切变而引起热带Ｏ３分布的年际变化，而且通过影响行星波的传播引起了行星波对Ｏ３输运的年际变化，这表现为当热带纬向风处于东风位相时，中高纬地区行星波对Ｏ３的输运比西风位相时强。  相似文献   

Natural and anthropogenic C2 to C6 hydrocarbons in the central-eastern Venezuelan atmosphere during the rainy season     

Loreto Donoso  Rodrigo Romero  Alberto Rondón  Emmanuel Fernandez  Pedro Oyola  Eugenio Sanhueza 《Journal of Atmospheric Chemistry》1996,25(2):201-214

The levels of low molecular weight hydrocarbons were measured at pristine sites and rural locations affected by hydrocarbon emissions from oil and gas producing fields in Venezuela. At the clean sites, lower concentrations of C₂ to C₆ alkanes were observed, whereas, in comparison with remotes sites, very much higher levels were measured at the polluted sites. Alkenes present relatively high concentrations, with isoprene being the most abundant, all over the study region. The main sources of alkenes are likely to be natural, mainly from vegetation. The levels of alkanes recorded at the clean sites and the alkene levels found everywhere in the region are in agreement with the values reported for other clean sites in the tropics. The increase of ozone production capacity due to the anthropogenic emissions of alkanes from oil and gas fields was estimated. Due to the presence in the atmosphere of important amounts of naturally emitted isoprene, ethene and propene, which makes a substantial contribution to the reactivity of the hydrocarbon mixture, a small increase (<5%) was estimated to occur in the capacity of the ozone production at a regional scale during the rainy season.  相似文献   

Accuracy of ozonesonde measurements in the troposphere     

S. J. Reid  G. Vaughan  A. R. W. Marsh  H. G. J. Smit 《Journal of Atmospheric Chemistry》1996,25(2):215-226

Measurements of atmospheric ozone at concentrations typical of the free troposphere have been compared for ECC sondes and a UV-absorption photometer, using a Bendix chemiluminescent analyser as a transfer standard. Comparisons were conducted in the laboratory and in the tropospheric part of the atmosphere. It was found that the measurements agreed to within 4% provided that the background current for the ECC sonde was measured before exposure to ozone in the preparation procedure, and was assumed to be constant throughout the sonde flight. These results confirm those of earlier experiments and mean that the methods currently used to correct for the background current in the troposphere need to be revised.  相似文献   

Collection and analysis of atmospheric ozone samples     

J. Stehr  D. Krankowsky  K. Mauersberger 《Journal of Atmospheric Chemistry》1996,24(3):317-325

Anomalies found in the isotope ratios of ozone are traceable to the ozone formation process. Metastable electronic states may be responsible for the preferred production of the heavy molecules. While laboratory isotope data and first tropospheric results agree well in the magnitude of isotope enrichments, stratospheric measurements show often higher values. Only through the collection of ozone samples can sufficiently large amounts of gas be obtained to analyze the three isotopes ⁴⁸O₃, ⁴⁹O₃, and ⁵⁰O₃. Collector systems have been developed and successfully operated in the troposphere and in the stratosphere. They will play in the future an important role in atmospheric oxygen isotope studies.  相似文献   

Boundary-layer ozone depletion as seen in the Norwegian Arctic in spring     

Sverre Solberg  Norbert Schmidbauer  Arne Semb  Frode Stordal  Øystein Hov 《Journal of Atmospheric Chemistry》1996,23(3):301-332

Several years of measurements of ozone, hydrocarbons, sulphate and meteorological parameters from Spitsbergen in the Norwegian Arctic are presented. Most of the measurements were taken on the Zeppelin Mountain at an altitude of 474 m a.s.l. The focus is the episodes of ozone depletion in the lower troposphere in spring, which are studied in a climatological way. Episodes of very low ozone concentrations are a common feature on the Zeppelin Mountain in spring. The low ozone episodes were observed from late March to the beginning of June. When the effect of transport direction was subtracted, the frequenty of the low ozone episodes was found to peak in the beginning of May, possibly reflecting the seasonal cycle in the actual depletion process. Analyses based on trajectory calculations show that most of the episodes occurred when the air masses were transported from W-N. Ozone soundings show that the ozone depletion may extend from the surface and up to 3–4 km altitude. The episodes were associated with a cold boundary layer beneath a thermally stable layer, suppressing mixing with the free troposphere. The concentration of several individual hydrocarbons was much lower during episodes of low ozone than for the average conditions. The change in concentration ratio between the hydrocarbons was in qualitative agreement with oxidation of hydrocarbons by Br and Cl atoms rather than by OH radicals.  相似文献   

NO2 total column evolution during the 1989 spring at Antarctica Peninsula     

Manuel Gil  Javier Cacho 《Journal of Atmospheric Chemistry》1992,15(2):187-200

Ground-based visible differential absorption spectrometry during twilight has been used for NO₂ total column observations at the Antarctica Peninsula, Marambio Base (64S, 56W), during the austral spring of 1989 (9 September to 25 November).Results show moderate NO₂ vertical column levels of 1.5 to 2.5×10¹⁵ molec cm^-2 in the morning and 2 to 3×10¹⁵ molec cm^-2 in the evening until middle October, highly modulated by planetary wave activity. From that date until the end of the period, a steady increase occurs which is associated with the rising of lower stratosphere temperature as the vortex weakens, reaching values of 5×10¹⁵ molec cm^-2 in late November, with small a.m.-p.m. differences. NO₂ is found to be positively correlated to both total ozone and 50 hPa temperature during the entire spring. However, when analyzing the departures from linear trends, a highly negative correlation has been observed from day 301 onwards.  相似文献