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221.
222.
C. O. Oluwafemi 《Pure and Applied Geophysics》1980,118(2):775-782
Solar radiance measurements covering over seventeen months are analysed for a location beside the Lagos Lagoon. The aerosol extinction coefficient was generally higher in the dusty months than in the wet months. Clean air estimates of the coefficient are made. Data on its wavelength dependence are also presented. 相似文献
223.
R. Jaenicke 《Pure and Applied Geophysics》1978,116(2-3):283-292
An estimated budget of organic substances in the atmosphere is compiled to whow the importance of organics in the aerosol. The distribution of organic compounds in background aerosols is estimated and it will be shown that the Aitken particles probably consist of roughly one quarter of organic substances. This is important for the dynamics of the aerosol and calculations are presented to estimate the aerosol production distribution for gas-to-particle conversion processes. 相似文献
224.
Priv.-Doz. Dr. med. H. Rüden Prof. Dr. med. E. Thofern Dr. med. P. Fischer Dr. Ing. U. Mihm 《Pure and Applied Geophysics》1978,116(2-3):335-350
For a period of approximately six months the concentrations of airborne microorganisms were determined by the uptake of their day-characteristic at local places differing by the extent of air pollution. By simultaneously recording the meteorological parameters as temperature, relative humidity, direction and velocity of wind and intensity of solar radiation, it was intended to find out the relationship between these factors and the viability of airborne microorganisms. The present data show an oscillation of the concentration counts over a wide range and seem not yet to depend on the local situation of air pollution.In a further series of experiments the atmospheric aerosol <10 m was collected on air-filters. The decreased substances were extracted from the filter material by aqueous and organic solutants and tested for their antimicrobial activities. In this context the seasonal dependence of the microbicidal activity of organic compounds of aerosol is discussed. 相似文献
225.
The surface tension lowering by surface-active substances has been measured on rainwater, melted snow, and dispersions of
atmospheric particles in water, with a film balance and a tensiometer. The precipitation water was sampled during 1979, 1980,
and 1981 in the city of Frankfurt/Main. From measurements with the film balance technique, normalized concentrations of insoluble
and weakly soluble surface-active substances have been estimated. Soluble surface-active substances were determined from measurements
with a tensiometer.
It was found that the normalized concentration of theinsoluble and weakly soluble surface-active material on rainwater or melted snow shows a maximum during late spring of about 2.5 · 10−7 moles/l and a minimum during wintertime of about 5 · 10−8 moles/l. These concentrations are too low to influence significantly the condensation of water vapour on cloud droplets or
the evaporation of water from them. Thesoluble surface-active material on rainwater or melted snow was found to have concentrations of the order of 2 · 10−6 moles/l. These concentrations are also too small to have a significant influence on cloud physical processes. 相似文献
226.
Fifteen samples of (Mg,Fe)SiO3 majorite with varying Fe/Mg composition and one sample of (Mg,Fe)(Si,Al)O3 majorite were synthesized at high pressure and temperature under different conditions of oxygen fugacity using a multianvil press, and examined ex situ using X-ray diffraction and Mössbauer and optical absorption spectroscopy. The relative concentration of Fe3+ increases both with total iron content and increasing oxygen fugacity, but not with Al concentration. Optical absorption spectra indicate the presence of Fe2+–Fe3+ charge transfer, where band intensity increases with increasing Fe3+ concentration. Mössbauer data were used in conjunction with electron microprobe analyses to determine the site distribution of all cations. Both Al and Fe3+ substitute on the octahedral site, and charge balance occurs through the removal of Si. The degree of Mg/Si ordering on the octahedral sites in (Mg,Fe)SiO3 majorite, which affects both the c/a ratio and the unit cell volume, is influenced by the thermal history of the sample. The Fe3+ concentration of (Mg,Fe)(Si,Al)O3 majorite in the mantle will reflect prevailing redox conditions, which are believed to be relatively reducing in the transition zone. Exchange of material across the transition boundary to (Mg,Fe) (Si,Al)O3 perovskite would then require a mechanism to oxidize sufficient iron to satisfy crystal-chemical requirements of the lower-mantle perovskite phase. 相似文献
227.
层积云覆盖的海洋边界层云详细微物理过程的数值模拟 总被引:1,自引:0,他引:1
文中建立了一个含显式分档的云微物理模式和辐射传输模式的一维 3阶湍流闭合模式 ,该模式可用于研究海洋边界层云中气溶胶和云的相互作用过程 ,同时提出了一种新的动力模式和微物理模式耦合方法 ,该方法可使动力模式中液态水相关项可以直接由微物理模式变量计算得到。作为模式的初步应用模拟了 2 0 0 1年APEX/ACE Asia在西太平洋上所观测到的一个个例。模拟结果和观测资料比较表明该模式基本上模拟出层积云覆盖的海洋边界层的基本结构 相似文献
228.
Kazuaki Kawamoto Tadahiro Hayasaka Teruyuki Nakajima David Streets Jung-Hun Woo 《Atmospheric Research》2004,72(1-4):353
The relationship between SO2 emissions and the effective particle radius of low-level water clouds (re) over China was investigated to determine anthropogenic effects on clouds. Sulfur dioxide emission values were obtained from a statistical inventory, and re origins were retrieved by satellite remote sensing on a 0.5° grid. Comparisons between annual mean SO2 emissions and re showed generally decreasing re values, explained by the Twomey effect. The existence of the Twomey effect is supported by comparisons with simulated aerosol optical depths. Results further suggest that clouds over land show sensitivity to the Twomey effect as well as clouds over the ocean. 相似文献
229.
Geochemical characterization, correlation, and optical dating of tephra in alluvial sequences of central western Argentina 总被引:1,自引:0,他引:1
The synthesis of paleoclimatic archives provided by loess and alluvial sequences of central Argentina has been hindered by the lack of a cohesive lithostratigraphic framework extending across the Chaco-Pampean plains and catchments of the Rios Desaguadero, Colorado, and Negro. This condition originates in part from the dearth of absolute chronological controls. The occurrence of discrete tephra layers across this region may provide an opportunity to address this deficiency if a tephrochronological framework can be established. The potential of such a project is assessed within the context of a pilot study constrained within alluvial sequences of central western Argentina proximal to potential source vents in the Southern Volcanic Zone. The intersite discrimination and correlation of tephra layers on a geochemical basis is examined, with indirect chronological control for the eruption of each generated by optical dating. Alluvial sediments on either side of each of five tephra units at a type site were dated using the optically stimulated luminescence of fine-silt-sized quartz, thus providing an age control on each tephra (ca. 24,000, 30,000, 32,000, 39,000, and 48,000 yr). The geochemical composition of each tephra was derived. Using these data, tephra layers at other sites in the study area were geochemically analyzed and, in instances of statistical concordance in major oxide structure, correlated to the type site and therefore ascribed ages. This methodology identified a further sixth volcanic event between ca. 24,000 and 30,000 yr not registered by type-site tephras. The extension of this initial tephrochronological framework beyond the alluvial sequences of central western Argentina is encouraged by the occurrence of geochemically distinct tephra verified and dated in this study. 相似文献
230.
本文扼要介绍了PMOE行星历表研究当前的进展和工作 ,给出了PMOE2 0 0 2与DE40 5历表的比较。 相似文献