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121.
O. Klemm W. R. Stockwell H. Schlager M. Krautstrunk 《Journal of Atmospheric Chemistry》2000,35(1):1-18
The ozone forming potential of VOCs and NOx for plumes observed from several cities and a power plant in eastern Germany was investigated. A closed box model with a gas phase photochemical reaction mechanism was employed to simulate several scenarios based upon aircraft observations. In several of the scenarios, the initial concentrations of NOx, VOCs, and SO2, were reduced to study the factors limiting the O3 production. Ozone production was limited by the initial VOC concentrations for all of the simulated plumes. Higher O3 concentrations were produced with reduced initial NOx. In one sample with high SO2 mixing ratios (>100 ppb), SO2 was also identified as a significant contributor to the production of O3. 相似文献
122.
123.
利用华中区域代表性站点金沙国家大气本底站2007—2018年的PM2.5、PM10颗粒物质量浓度数据,2019年3月—2019年6月反应性气体数据,对华中区域空气质量进行整体评价,并分析了颗粒物浓度的变化特征及其影响因素.结果表明,反应性气体CO、SO2、NO、NO2质量浓度其日平均最大值、平均值均达到一级标准,O3日... 相似文献
124.
通过对卫星资料的分析,揭示了全球大尺度山地上空有大气臭氧亏损,其极大值出现在春季或初夏,线性回归分析表明:在1979~1991年中,全球大尺度山地上空的臭氧总量呈下降趋势。 相似文献
125.
Howard B. Ross Christer Johansson Claes de Serves John Lind 《Journal of Atmospheric Chemistry》1992,14(1-4):411-423
Atmospheric peroxides and formaldehyde were measured at two sites in Sweden; inside a Scots pine stand (Jädraås) and on top of Mt. Åreskutan (1250 msl). Peroxide levels at Jädraås were highest during the day and lowest during the night. Mid-day concentrations of H2O2 varied between 0.05 and 2 ppbv. Isentropic trajectories together with local O3 measurements indicated the importance of long range transport on surface H2O2 lévels. Large diurnal variations and vertical profiles showed the importance of turbulent mixing processes and dry deposition. A comparison of H2O2 and O3 diurnal variations indicated a more rapid dry deposition of H2O2 to the forest. It would appear that terpenes emitted from the forest play a minor role in controlling the H2O2 levels. Formaldehyde at Jädraås had a different diurnal variation than peroxides; highest levels were observed in the early evening indicating chemical production of CH2O. Diurnal variations of peroxides on Mt Åreskutan were opposite to those at Jädraås, highest concentrations were observed during the night. This result is to be expected if during the day air from inside the valley, with lower peroxide levels relative to the free troposphere, rises to the mountain top. In the evening, subsidence brings free tropospheric air with higher peroxides levels to the mountain. 相似文献
126.
127.
We call attention to the likely importance of the potential reaction OH+ClOHCl+O2. It may only be a minor channel for the reaction of OH with ClO, which is often ignored in models, but if it occurs it considerably increases the rate of recovery of HCl after an air parcel has encountered a polar stratospheric cloud (PSC). The net effect of this reaction on the ozone concentration depends on the relative HCl concentration and whether the air parcel is in a PSC. When an air parcel is in a PSC and the HCl concentration is less than the sum of the HOCl and ClONO2 concentrations, heterogeneous ClO
x
production is rate limited by the production of HCl. Under these conditions the reaction allows HCl to be reprocessed more rapidly by the heterogeneous reactions of HCl with HOCl and ClONO2. This allows high ClO
x
concentration to be maintained for longer, and at a slightly higher level, than would otherwise be possible which in turn leads to more ozone depletion. When there are PSCs but HCl is in excess, or outside of the PSC regions (i.e. during the recovery phase), the reaction will always reduce the ClO/HCl ratio and hence slightly reduce the ozone loss. 相似文献
128.
The actinic flux is the only radiometric quantity suitable for photolysisfrequency determination. It is derived from solar spectral irradiancemeasurements performed by a portable spectroradiometer in the 300–850nm wavelength range. The spectral irradiance is first divided into a directpart and a diffuse part, according to the atmospheric conditions, and thenconverted into the corresponding actinic flux quantity. As an intermediary,the ratio
of diffuse actinic flux to diffuseirradiance is calculated by the spherical harmonics radiative code withrespect to wavelength, solar zenith angle, surface albedo, and aerosolproperties.The results of extensive sensitivity studies of
asa function of the main atmospheric parameters are discussed and lead to theconclusion that aerosol optical depth is the major critical value for aprecise
determination. The global algorithm totransform spectral irradiance into actinic flux is finally applied forphotodissociation rate calculations by convolution of the obtained actinicflux spectra with the absorption cross-sections and quantum yields of themolecule studied. Photolysis rates of different atmospheric photooxidants havebeen measured with this spectroradiometric method during the summers of 1993and 1994 in Brittany and in Portugal. The ozone and nitrogen dioxidephotodissociation rates obtained present a good agreement with thej(O3) and j(NO2) actinometerresults, for the same experimental conditions in Brittany. 相似文献
129.
利用全大气气候通用模式(WACCM3)对政府间气候变化专门委员会排放情景特别报告中2001年到2099年A1B、A2、B1三种排放情景进行了模拟,分析了三种排放情景下青藏高原地区未来百年臭氧总量在夏季(6—8月)的变化趋势及引起该变化的可能机制。结果表明:在三种排放情景下未来百年夏季高原区臭氧总量均呈现增长趋势,其中A2情景下臭氧增长最快,B1情景下增长最慢,但相对于同纬度其他地区,高原区的臭氧总量增长较慢,即高原区臭氧谷加深。高原区高空污染物的减少以及局域Hadley环流的减弱是未来高原区臭氧总量增加的原因;而南亚高压的增强,以及与之相对应的辐散增强则可能是高原区臭氧谷继续加深的原因。 相似文献
130.
采用密度泛函理论对氟利昂R12及其替代物R134a在B3LYP/6-311G++(d,p)基组水平上进行结构优化和特征光谱计算.首次在该高精度基组下优化得到了R12和R134a的键长、键角和二面角等分子构型参数,且通过进一步的计算,得到了这两种分子的红外光谱和拉曼光谱.其中R12红外光谱的计算结果与美国国家标准局数据库(NIST)提供的实验结果基本吻合,说明了计算结果的准确性.另外通过从头算CIS方法对能量进行计算,得到了R12和R134a的紫外可见吸收光谱.计算结果可为进一步保护大气臭氧提供有用的数据参考. 相似文献